[xiph-commits] r11761 - trunk/speex/doc

[jm at svn.xiph.org]

Author: jm
Date: 2006-08-11 23:13:47 -0700 (Fri, 11 Aug 2006)
New Revision: 11761

Modified:
   trunk/speex/doc/manual.lyx
Log:
Updated API-related parts (codec + AEC).


Modified: trunk/speex/doc/manual.lyx
===================================================================
--- trunk/speex/doc/manual.lyx	2006-08-12 03:32:45 UTC (rev 11760)
+++ trunk/speex/doc/manual.lyx	2006-08-12 06:13:47 UTC (rev 11761)
@@ -1,42 +1,51 @@
-#LyX 1.3 created this file. For more info see http://www.lyx.org/
-\lyxformat 221
+#LyX 1.4.2 created this file. For more info see http://www.lyx.org/
+\lyxformat 245
+\begin_document
+\begin_header
 \textclass article
 \language english
 \inputencoding auto
 \fontscheme pslatex
 \graphics default
 \paperfontsize default
-\spacing onehalf 
+\spacing onehalf
 \papersize letterpaper
-\paperpackage a4
-\use_geometry 0
-\use_amsmath 0
-\use_natbib 0
-\use_numerical_citations 0
+\use_geometry false
+\use_amsmath 1
+\cite_engine basic
+\use_bibtopic false
 \paperorientation portrait
 \secnumdepth 3
 \tocdepth 3
 \paragraph_separation indent
 \defskip medskip
 \quotes_language english
-\quotes_times 2
 \papercolumns 1
 \papersides 1
 \paperpagestyle headings
+\tracking_changes false
+\output_changes true
+\end_header
 
-\layout Title
+\begin_body
 
+\begin_layout Title
 The Speex Codec Manual
-\newline 
-(version 1.1.11)
-\layout Author
+\newline
+(version 1.2-beta1)
+\end_layout
 
+\begin_layout Author
 Jean-Marc Valin
-\layout Standard
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
 Copyright (c) 2002-2005 Jean-Marc Valin/Xiph.org Foundation
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Permission is granted to copy, distribute and/or modify this document under
  the terms of the GNU Free Documentation License, Version 1.1 or any later
  version published by the Free Software Foundation; with no Invariant Section,
@@ -44,31 +53,40 @@
  A copy of the license is included in the section entitled "GNU Free Documentati
 on License".
  
-\layout Standard
-\pagebreak_top \pagebreak_bottom 
+\end_layout
 
+\begin_layout Standard
+
+\newpage
+
 \begin_inset LatexCommand \tableofcontents{}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
-\pagebreak_bottom 
+\newpage
 
+\end_layout
+
+\begin_layout Standard
 \begin_inset FloatList table
 
-\end_inset 
+\end_inset
 
 
-\layout Section
+\newpage
 
+\end_layout
+
+\begin_layout Section
 Introduction to Speex
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The Speex project (
-\family typewriter 
+\family typewriter
 http://www.speex.org/
-\family default 
+\family default
 ) has been started because there was a need for a speech codec that was
  open-source and free from software patents.
  These are essential conditions for being used by any open-source software.
@@ -78,122 +96,136 @@
  (not many open-source cell phones anyway :-) ) but rather at voice over
  IP (VoIP) and file-based compression.
  
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 As design goals, we wanted to have a codec that would allow both very good
  quality speech and low bit-rate (unfortunately not at the same time!),
  which led us to developing a codec with multiple bit-rates.
  Of course very good quality also meant we had to do wideband (16 kHz sampling
  rate) in addition to narrowband (telephone quality, 8 kHz sampling rate).
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Designing for VoIP instead of cell phone use means that Speex must be robust
  to lost packets, but not to corrupted ones since packets either arrive
  unaltered or don't arrive at all.
  Also, the idea was to have a reasonable complexity and memory requirement
  without compromising too much on the efficiency of the codec.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 All this led us to the choice of CELP
 \begin_inset LatexCommand \index{CELP}
 
-\end_inset 
+\end_inset
 
  as the encoding technique to use for Speex.
  One of the main reasons is that CELP has long proved that it could do the
  job and scale well to both low bit-rates (think DoD CELP @ 4.8 kbps) and
  high bit-rates (think G.728 @ 16 kbps).
  
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The main characteristics can be summarized as follows:
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Free software/open-source
 \begin_inset LatexCommand \index{open-source}
 
-\end_inset 
+\end_inset
 
 , patent
 \begin_inset LatexCommand \index{patent}
 
-\end_inset 
+\end_inset
 
  and royalty-free
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Integration of narrowband
 \begin_inset LatexCommand \index{narrowband}
 
-\end_inset 
+\end_inset
 
  and wideband
 \begin_inset LatexCommand \index{wideband}
 
-\end_inset 
+\end_inset
 
  using an embedded bit-stream
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Wide range of bit-rates available (from 2 kbps to 44 kbps)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Dynamic bit-rate switching and Variable Bit-Rate
 \begin_inset LatexCommand \index{variable bit-rate}
 
-\end_inset 
+\end_inset
 
  (VBR)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Voice Activity Detection
 \begin_inset LatexCommand \index{voice activity detection}
 
-\end_inset 
+\end_inset
 
  (VAD, integrated with VBR)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Variable complexity
 \begin_inset LatexCommand \index{complexity}
 
-\end_inset 
+\end_inset
 
 
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Ultra-wideband mode at 32 kHz (up to 48 kHz)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Intensity stereo encoding option
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Fixed-point implementation (work in progress)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This document is divided in the following way.
  Section 
 \begin_inset LatexCommand \ref{sec:Feature-description}
 
-\end_inset 
+\end_inset
 
  describes the different Speex features and defines some terms that will
  be used in later sections.
  Section 
 \begin_inset LatexCommand \ref{sec:Command-line-encoder/decoder}
 
-\end_inset 
+\end_inset
 
  provides information about the standard command-line tools, while 
 \begin_inset LatexCommand \ref{sec:Programming-with-Speex}
 
-\end_inset 
+\end_inset
 
  contains information about programming using the Speex API.
  Section 
 \begin_inset LatexCommand \ref{sec:Formats-and-standards}
 
-\end_inset 
+\end_inset
 
  has some information related to Speex and standards.
  The three last sections describe the internals of the codec and require
@@ -201,110 +233,126 @@
  Section 
 \begin_inset LatexCommand \ref{sec:Introduction-to-CELP}
 
-\end_inset 
+\end_inset
 
  explains the general idea behind CELP, while sections 
 \begin_inset LatexCommand \ref{sec:Speex-narrowband-mode}
 
-\end_inset 
+\end_inset
 
  and 
 \begin_inset LatexCommand \ref{sec:Speex-wideband-mode}
 
-\end_inset 
+\end_inset
 
  are specific to Speex.
  Note that if you are only interested in using Speex, those three last sections
  are not required.
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Codec description
 \begin_inset LatexCommand \label{sec:Feature-description}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This section describes the main features provided by Speex.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Concepts
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Here are some concepts in speech coding that help better understand the
  rest of the manual.
  Emphasis is placed on the Speex features.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Sampling rate
 \begin_inset LatexCommand \index{sampling rate}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex is mainly designed for 3 different sampling rates: 8 kHz, 16 kHz,
  and 32 kHz.
  These are respectively refered to as narrowband
 \begin_inset LatexCommand \index{narrowband}
 
-\end_inset 
+\end_inset
 
 , wideband
 \begin_inset LatexCommand \index{wideband}
 
-\end_inset 
+\end_inset
 
  and ultra-wideband
 \begin_inset LatexCommand \index{ultra-wideband}
 
-\end_inset 
+\end_inset
 
 .
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Quality
 \begin_inset LatexCommand \index{quality}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex encoding is controlled most of the time by a quality parameter that
  ranges from 0 to 10.
  In constant bit-rate
 \begin_inset LatexCommand \index{constant bit-rate}
 
-\end_inset 
+\end_inset
 
  (CBR) operation, the quality parameter is an integer, while for variable
  bit-rate (VBR), the parameter is a float.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Complexity
 \begin_inset LatexCommand \index{complexity}
 
-\end_inset 
+\end_inset
 
  (variable)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 With Speex, it is possible to vary the complexity allowed for the encoder.
  This is done by controlling how the search is performed with an integer
  ranging from 1 to 10 in a way that's similar to the -1 to -9 options to
  
-\emph on 
+\emph on
 gzip
-\emph default 
+\emph default
  and 
-\emph on 
+\emph on
 bzip2
-\emph default 
+\emph default
  compression utilities.
  For normal use, the noise level at complexity 1 is between 1 and 2 dB higher
  than at complexity 10, but the CPU requirements for complexity 10 is about
@@ -313,27 +361,29 @@
  settings are often useful when encoding non-speech sounds like DTMF
 \begin_inset LatexCommand \index{DTMF}
 
-\end_inset 
+\end_inset
 
  tones.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Variable Bit-Rate
 \begin_inset LatexCommand \index{variable bit-rate}
 
-\end_inset 
+\end_inset
 
  (VBR)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Variable bit-rate (VBR) allows a codec to change its bit-rate dynamically
  to adapt to the 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 difficulty
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  of the audio being encoded.
  In the example of Speex, sounds like vowels and high-energy transients
@@ -346,31 +396,35 @@
  Second, for some real-time applications like voice over IP (VoIP), what
  counts is the maximum bit-rate, which must be low enough for the communication
  channel.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Average Bit-Rate
 \begin_inset LatexCommand \index{average bit-rate}
 
-\end_inset 
+\end_inset
 
  (ABR)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Average bit-rate solves one of the problems of VBR, as it dynamically adjusts
  VBR quality in order to meet a specific target bit-rate.
  Because the quality/bit-rate is adjusted in real-time (open-loop), the
  global quality will be slightly lower than that obtained by encoding in
  VBR with exactly the right quality setting to meet the target average bit-rate.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Voice Activity Detection
 \begin_inset LatexCommand \index{voice activity detection}
 
-\end_inset 
+\end_inset
 
  (VAD)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 When enabled, voice activity detection detects whether the audio being encoded
  is speech or silence/background noise.
  VAD is always implicitly activated when encoding in VBR, so the option
@@ -379,100 +433,113 @@
  enough bits to reproduce the background noise.
  This is called 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 comfort noise generation
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  (CNG).
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Discontinuous Transmission
 \begin_inset LatexCommand \index{discontinuous transmission}
 
-\end_inset 
+\end_inset
 
  (DTX)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Discontinuous transmission is an addition to VAD/VBR operation, that allows
  to stop transmitting completely when the background noise is stationary.
  In file-based operation, since we cannot just stop writing to the file,
  only 5 bits are used for such frames (corresponding to 250 bps).
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Perceptual enhancement
 \begin_inset LatexCommand \index{perceptual enhancement}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Perceptual enhancement is a part of the decoder which, when turned on, tries
  to reduce (the perception of) the noise produced by the coding/decoding
  process.
  In most cases, perceptual enhancement make the sound further from the original
  
-\emph on 
+\emph on
 objectively
-\emph default 
+\emph default
  (if you use SNR), but in the end it still 
-\emph on 
+\emph on
 sounds
-\emph default 
+\emph default
  better (subjective improvement).
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Algorithmic delay
 \begin_inset LatexCommand \index{algorithmic delay}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Every speech codec introduces a delay in the transmission.
  For Speex, this delay is equal to the frame size, plus some amount of 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 look-ahead
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  required to process each frame.
  In narrowband operation (8 kHz), the delay is 30 ms, while for wideband
  (16 kHz), the delay is 34 ms.
  These values don't account for the CPU time it takes to encode or decode
  the frames.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Codec
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Preprocessor
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This part refers to the preprocessor module introduced in the 1.1.x branch.
  The preprocessor is designed to be used on the audio 
-\emph on 
+\emph on
 before
-\emph default 
+\emph default
  running the encoder.
  The preprocessor provides three main functionalities:
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 denoising
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 automatic gain control (AGC)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 voice activity detection (VAD)
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The denoiser can be used to reduce the amount of background noise present
  in the input signal.
  This provides higher quality speech whether or not the denoised signal
@@ -482,8 +549,9 @@
  Speech codecs in general (Speex included) tend to perform poorly on noisy
  input, which tends to amplify the noise.
  The denoiser greatly reduces this effect.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Automatic gain control (AGC) is a feature that deals with the fact that
  the recording volume may vary by a large amount between different setups.
  The AGC provides a way to adjust a signal to a reference volume.
@@ -491,732 +559,906 @@
  adjustment of the microphone gain.
  A secondary advantage is that by setting the microphone gain to a conservative
  (low) level, it is easier to avoid clipping.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The voice activity detector (VAD) provided by the preprocessor is more advanced
  than the one directly provided in the codec.
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Adaptive Jitter Buffer
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Acoustic Echo Canceller
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Compiling
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Compiling Speex under UNIX or any platform supported by autoconf (e.g.
  Win32/cygwin) is as easy as typing:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 % ./configure [options]
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 % make
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 % make install
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The options supported by the Speex configure script are:
-\layout Description
+\end_layout
 
+\begin_layout Description
 --prefix=<path> Specifies where to install Speex
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-shared/--disable-shared Whether to compile shared libraries
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-static/--disable-static Whether to compile static libraries
-\layout Description
+\end_layout
 
+\begin_layout Description
 --disable-wideband Disable the wideband part of Speex (typically to same
  space)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-valgrind Enable extra information when (and only when) running
  with valgrind
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-sse Enable use of SSE instructions (x86/float only)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-fixed-point
 \begin_inset LatexCommand \index{fixed-point}
 
-\end_inset 
+\end_inset
 
  Compile Speex for a processor that does not have a floating point unit
  (FPU)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-arm4-asm Enable assembly specific to the ARMv4 architecture (gcc
  only)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-arm5e-asm Enable assembly specific to the ARMv5E architecture (gcc
  only)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-fixed-point-debug Use only for debugging the fixed-point
 \begin_inset LatexCommand \index{fixed-point}
 
-\end_inset 
+\end_inset
 
  code (very slow)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-epic-48k Enable a special (and non-compatible) 4.8 kbps narrowband
  mode
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-ti-c55x Enable support for the TI C5x family
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-blackfin-asm Enable assembly specific to the Blackfin DSP architecture
  (gcc only)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enable-16bit-precision Reduces precision to 16 bits in time-critical areas
  (fixed-point only)
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Command-line encoder/decoder
 \begin_inset LatexCommand \label{sec:Command-line-encoder/decoder}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The base Speex distribution includes a command-line encoder (
-\emph on 
+\emph on
 speexenc
-\emph default 
+\emph default
 ) and decoder (
-\emph on 
+\emph on
 speexdec
-\emph default 
+\emph default
 ).
  This section describes how to use these tools.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 
-\emph on 
+\emph on
 speexenc
 \begin_inset LatexCommand \index{speexenc}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The 
-\emph on 
+\emph on
 speexenc
-\emph default 
+\emph default
  utility is used to create Speex files from raw PCM or wave files.
  It can be used by calling: 
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speexenc [options] input_file output_file
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The value '-' for input_file or output_file corresponds respectively to
  stdin and stdout.
  The valid options are:
-\layout Description
+\end_layout
 
---narrowband\SpecialChar ~
+\begin_layout Description
+--narrowband\InsetSpace ~
 (-n) Tell Speex to treat the input as narrowband (8 kHz).
  This is the default
-\layout Description
+\end_layout
 
---wideband\SpecialChar ~
+\begin_layout Description
+--wideband\InsetSpace ~
 (-w) Tell Speex to treat the input as wideband (16 kHz)
-\layout Description
+\end_layout
 
---ultra-wideband\SpecialChar ~
+\begin_layout Description
+--ultra-wideband\InsetSpace ~
 (-u) Tell Speex to treat the input as 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 ultra-wideband
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  (32 kHz)
-\layout Description
+\end_layout
 
---quality\SpecialChar ~
+\begin_layout Description
+--quality\InsetSpace ~
 n Set the encoding quality (0-10), default is 8
-\layout Description
+\end_layout
 
---bitrate\SpecialChar ~
+\begin_layout Description
+--bitrate\InsetSpace ~
 n Encoding bit-rate (use bit-rate n or lower) 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --vbr Enable VBR (Variable Bit-Rate), disabled by default
-\layout Description
+\end_layout
 
---abr\SpecialChar ~
+\begin_layout Description
+--abr\InsetSpace ~
 n Enable ABR (Average Bit-Rate) at n kbps, disabled by default
-\layout Description
+\end_layout
 
+\begin_layout Description
 --vad Enable VAD (Voice Activity Detection), disabled by default
-\layout Description
+\end_layout
 
+\begin_layout Description
 --dtx Enable DTX (Discontinuous Transmission), disabled by default
-\layout Description
+\end_layout
 
---nframes\SpecialChar ~
+\begin_layout Description
+--nframes\InsetSpace ~
 n Pack n frames in each Ogg packet (this saves space at low bit-rates)
-\layout Description
+\end_layout
 
---comp\SpecialChar ~
+\begin_layout Description
+--comp\InsetSpace ~
 n Set encoding speed/quality tradeoff.
  The higher the value of n, the slower the encoding (default is 3)
-\layout Description
+\end_layout
 
+\begin_layout Description
 -V Verbose operation, print bit-rate currently in use
-\layout Description
+\end_layout
 
---help\SpecialChar ~
+\begin_layout Description
+--help\InsetSpace ~
 (-h) Print the help
-\layout Description
+\end_layout
 
---version\SpecialChar ~
+\begin_layout Description
+--version\InsetSpace ~
 (-v) Print version information
-\layout Subsubsection*
+\end_layout
 
+\begin_layout Subsubsection*
 Speex comments
-\layout Description
+\end_layout
 
+\begin_layout Description
 --comment Add the given string as an extra comment.
  This may be used multiple times.
  
-\layout Description
+\end_layout
 
+\begin_layout Description
 --author Author of this track.
  
-\layout Description
+\end_layout
 
+\begin_layout Description
 --title Title for this track.
  
-\layout Subsubsection*
+\end_layout
 
+\begin_layout Subsubsection*
 Raw input options
-\layout Description
+\end_layout
 
---rate\SpecialChar ~
+\begin_layout Description
+--rate\InsetSpace ~
 n Sampling rate for raw input
-\layout Description
+\end_layout
 
+\begin_layout Description
 --stereo Consider raw input as stereo 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --le Raw input is little-endian 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --be Raw input is big-endian 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --8bit Raw input is 8-bit unsigned 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --16bit Raw input is 16-bit signed 
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 
-\emph on 
+\emph on
 speexdec
 \begin_inset LatexCommand \index{speexdec}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The 
-\emph on 
+\emph on
 speexdec
-\emph default 
+\emph default
  utility is used to decode Speex files and can be used by calling: 
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speexdec [options] speex_file [output_file]
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The value '-' for input_file or output_file corresponds respectively to
  stdin and stdout.
  Also, when no output_file is specified, the file is played to the soundcard.
  The valid options are:
-\layout Description
+\end_layout
 
+\begin_layout Description
 --enh enable post-filter (default)
-\layout Description
+\end_layout
 
+\begin_layout Description
 --no-enh disable post-filter
-\layout Description
+\end_layout
 
+\begin_layout Description
 --force-nb Force decoding in narrowband 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --force-wb Force decoding in wideband 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --force-uwb Force decoding in ultra-wideband 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --mono Force decoding in mono 
-\layout Description
+\end_layout
 
+\begin_layout Description
 --stereo Force decoding in stereo 
-\layout Description
+\end_layout
 
---rate\SpecialChar ~
+\begin_layout Description
+--rate\InsetSpace ~
 n Force decoding at n Hz sampling rate
-\layout Description
+\end_layout
 
---packet-loss\SpecialChar ~
+\begin_layout Description
+--packet-loss\InsetSpace ~
 n Simulate n % random packet loss
-\layout Description
+\end_layout
 
+\begin_layout Description
 -V Verbose operation, print bit-rate currently in use
-\layout Description
+\end_layout
 
---help\SpecialChar ~
+\begin_layout Description
+--help\InsetSpace ~
 (-h) Print the help
-\layout Description
+\end_layout
 
---version\SpecialChar ~
+\begin_layout Description
+--version\InsetSpace ~
 (-v) Print version information
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Programming with Speex (the libspeex
 \begin_inset LatexCommand \index{libspeex}
 
-\end_inset 
+\end_inset
 
  API
 \begin_inset LatexCommand \index{API}
 
-\end_inset 
+\end_inset
 
 )
 \begin_inset LatexCommand \label{sec:Programming-with-Speex}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This section explains how to use the Speex API.
  Examples of code can also be found in appendix 
 \begin_inset LatexCommand \ref{sec:Sample-code}
 
-\end_inset 
+\end_inset
 
 .
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Encoding
 \begin_inset LatexCommand \label{sub:Encoding}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In order to encode speech using Speex, you first need to:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 #include <speex/speex.h>
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You then need to declare a Speex bit-packing struct
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 SpeexBits bits;
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 and a Speex encoder state
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 void *enc_state;
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The two are initialized by:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_init(&bits);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 enc_state = speex_encoder_init(&speex_nb_mode);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For wideband coding, 
-\emph on 
+\emph on
 speex_nb_mode
-\emph default 
+\emph default
  will be replaced by 
-\emph on 
+\emph on
 speex_wb_mode
-\emph default 
+\emph default
 .
  In most cases, you will need to know the frame size used by the mode you
  are using.
  You can get that value in the 
-\emph on 
+\emph on
 frame_size
-\emph default 
+\emph default
  variable with:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_encoder_ctl(enc_state,SPEEX_GET_FRAME_SIZE,&frame_size);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In practice, 
-\emph on 
+\emph on
 frame_size
-\emph default 
+\emph default
  will correspond to 20 ms when using 8, 16, or 32 kHz sampling rate.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Once the initialization is done, for every input frame:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_reset(&bits);
-\layout LyX-Code
+\end_layout
 
-speex_encode(enc_state, input_frame, &bits);
-\layout LyX-Code
+\begin_layout LyX-Code
+speex_encode_int(enc_state, input_frame, &bits);
+\end_layout
 
+\begin_layout LyX-Code
 nbBytes = speex_bits_write(&bits, byte_ptr, MAX_NB_BYTES);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
-\emph on 
+\emph on
 input_frame
-\emph default 
+\emph default
  is a 
-\emph on 
-(float *)
-\emph default 
+\emph on
+(
+\emph default
+short
+\emph on
+ *)
+\emph default
  pointing to the beginning of a speech frame, 
-\emph on 
+\emph on
 byte_ptr
-\emph default 
+\emph default
  is a 
-\emph on 
+\emph on
 (char *)
-\emph default 
+\emph default
  where the encoded frame will be written, 
-\emph on 
+\emph on
 MAX_NB_BYTES
-\emph default 
+\emph default
  is the maximum number of bytes that can be written to 
-\emph on 
+\emph on
 byte_ptr
-\emph default 
+\emph default
  without causing an overflow and 
-\emph on 
+\emph on
 nbBytes
-\emph default 
+\emph default
  is the number of bytes actually written to 
-\emph on 
+\emph on
 byte_ptr
-\emph default 
+\emph default
  (the encoded size in bytes).
  Before calling speex_bits_write, it is possible to find the number of bytes
  that need to be written by calling 
-\family typewriter 
+\family typewriter
 speex_bits_nbytes(&bits)
-\family default 
+\family default
 , which returns a number of bytes.
-\layout Standard
+\end_layout
 
-When using an unstable release (1.1.x), it is possible to use the 
-\emph on 
-speex_encode_int()
-\emph default 
+\begin_layout Standard
+It is still possible to use the 
+\emph on
+speex_encode()
+\emph default
  function, which takes a 
-\emph on 
-(short *)
-\emph default 
+\emph on
+(float *)
+\emph default
  for the audio.
- This is usually simpler and it makes an eventual port to an FPU-less platform
- (like ARM) easier.
-\layout Standard
+ However, this would make an eventual port to an FPU-less platform (like
+ ARM) more complicated.
+ Internally, 
+\emph on
+speex_encode() 
+\emph default
+and
+\emph on
+ speex_encode_int()
+\emph default
+ are processed in the same way.
+ Whether the encoder uses the fixed-point version is only decided by the
+ compile-time flags, not at the API level.
+\end_layout
 
+\begin_layout Standard
 After you're done with the encoding, free all resources with:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_destroy(&bits);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_encoder_destroy(enc_state);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 That's about it for the encoder.
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Decoding
 \begin_inset LatexCommand \label{sub:Decoding}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In order to decode speech using Speex, you first need to:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 #include <speex/speex.h>
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You also need to declare a Speex bit-packing struct
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 SpeexBits bits;
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 and a Speex decoder state
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 void *dec_state;
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The two are initialized by:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_init(&bits);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 dec_state = speex_decoder_init(&speex_nb_mode);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For wideband decoding, 
-\emph on 
+\emph on
 speex_nb_mode
-\emph default 
+\emph default
  will be replaced by 
-\emph on 
+\emph on
 speex_wb_mode
-\emph default 
+\emph default
 .
  If you need to obtain the size of the frames that will be used by the decoder,
  you can get that value in the 
-\emph on 
+\emph on
 frame_size
-\emph default 
+\emph default
  variable with:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_decoder_ctl(dec_state, SPEEX_GET_FRAME_SIZE, &frame_size); 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 There is also a parameter that can be set for the decoder: whether or not
- to use a perceptual post-filter.
+ to use a perceptual enhancer.
  This can be set by: 
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_decoder_ctl(dec_state, SPEEX_SET_ENH, &enh); 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
-\emph on 
+\emph on
 enh
-\emph default 
- is an int that with value 0 to have the post-filter disabled and 1 to have
- it enabled.
-\layout Standard
+\emph default
+ is an int with value 0 to have the enhancer disabled and 1 to have it enabled.
+ As of 1.2-beta1, the default is now to enable the enhancer.
+\end_layout
 
+\begin_layout Standard
 Again, once the decoder initialization is done, for every input frame:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_read_from(&bits, input_bytes, nbBytes);
-\layout LyX-Code
+\end_layout
 
-speex_decode(dec_state, &bits, output_frame);
-\layout Standard
+\begin_layout LyX-Code
+speex_decode_int(dec_state, &bits, output_frame);
+\end_layout
 
+\begin_layout Standard
 where input_bytes is a 
-\emph on 
+\emph on
 (char *)
-\emph default 
+\emph default
  containing the bit-stream data received for a frame, 
-\emph on 
+\emph on
 nbBytes
-\emph default 
+\emph default
  is the size (in bytes) of that bit-stream, and 
-\emph on 
+\emph on
 output_frame
-\emph default 
+\emph default
  is a 
-\emph on 
-(float *)
-\emph default 
+\emph on
+(short *)
+\emph default
  and points to the area where the decoded speech frame will be written.
  A NULL value as the first argument indicates that we don't have the bits
  for the current frame.
  When a frame is lost, the Speex decoder will do its best to "guess" the
  correct signal.
-\layout Standard
+\end_layout
 
-As for the encoder, the 1.1.x branch introduces the 
-\emph on 
-speex_decode_int()
-\emph default 
- function which also uses a 
-\emph on 
-(short *)
-\emph default 
+\begin_layout Standard
+As for the encoder, the 
+\emph on
+speex_decode()
+\emph default
+ function can still be used, with a 
+\emph on
+(float *)
+\emph default
  as the output for the audio.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 After you're done with the decoding, free all resources with:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_bits_destroy(&bits);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_decoder_destroy(dec_state);
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Preprocessor
 \begin_inset LatexCommand \label{sub:Preprocessor}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In order to use the Speex preprocessor
 \begin_inset LatexCommand \index{preprocessor}
 
-\end_inset 
+\end_inset
 
 , you first need to:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 #include <speex/speex_preprocess.h>
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Then, a preprocessor state can be created as:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 SpeexPreprocessState *preprocess_state = speex_preprocess_state_init(frame_size,
  sampling_rate);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 It is recommended to use the same value for 
-\family typewriter 
+\family typewriter
 frame_size
-\family default 
+\family default
  as is used by the encoder (20 
-\emph on 
+\emph on
 ms
-\emph default 
+\emph default
 ).
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For each input frame, you need to call:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_preprocess(preprocess_state, audio_frame, echo_residue);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
-\family typewriter 
+\family typewriter
 audio_frame
-\family default 
+\family default
  is used both as input and output and 
-\family typewriter 
+\family typewriter
 echo_residue
-\family default 
+\family default
  is either an array filled by the echo canceller, or NULL if the preprocessor
  is used without the echo canceller.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In cases where the output audio is not useful for a certain frame, it is
  possible to use instead:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_preprocess_estimate_update(preprocess_state, audio_frame, echo_residue);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This call will update all the preprocessor internal state variables without
  computing the output audio, thus saving some CPU cycles.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The behaviour of the preprocessor can be changed using:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_preprocess_ctl(preprocess_state, request, ptr);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 which is used in the same way as the encoder and decoder equivalent.
  Options are listed in Section .
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The preprocessor state can be destroyed using:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_preprocess_state_destroy(preprocess_state);
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Echo Cancellation
 \begin_inset LatexCommand \label{sub:Echo-Cancellation}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The Speex library now includes an echo cancellation
 \begin_inset LatexCommand \index{echo cancellation}
 
-\end_inset 
+\end_inset
 
  algorithm suitable for Acoustic Echo Cancellation
 \begin_inset LatexCommand \index{acoustic echo cancellation}
 
-\end_inset 
+\end_inset
 
  (AEC).
  In order to use the echo canceller, you first need to
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 #include <speex/speex_echo.h>
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Then, an echo canceller state can be created by:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 SpeexEchoState *echo_state = speex_echo_state_init(frame_size, filter_length);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
-\family typewriter 
+\family typewriter
 frame_size
-\family default 
+\family default
  is the amount of data (in samples) you want to process at once and 
-\family typewriter 
+\family typewriter
 filter_length
-\family default 
+\family default
  is the length (in samples) of the echo cancelling filter you want to use
  (also known as 
-\shape italic 
+\shape italic
 tail length
-\shape default 
+\shape default
 
 \begin_inset LatexCommand \index{tail length}
 
-\end_inset 
+\end_inset
 
 ).
  It is recommended to use a frame size in the order of 20 ms (or equal to
@@ -1227,52 +1469,56 @@
  For example, in a small room, reverberation time is in the order of 300
  ms, so a tail length of 100 ms is a good choice (800 samples at 8000 Hz
  sampling rate).
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Once the echo canceller state is created, audio can be processed by:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_echo_cancel(echo_state, input_frame, echo_frame, output_frame, residue);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
-\family typewriter 
+\family typewriter
 input_frame
-\family default 
+\family default
  is the audio as captured by the microphone, 
-\family typewriter 
+\family typewriter
 echo_frame
-\family default 
+\family default
  is the signal that was played in the speaker (and needs to be removed)
  and 
-\family typewriter 
+\family typewriter
 output_frame
-\family default 
+\family default
  is the signal with echo removed.
  The 
-\family typewriter 
+\family typewriter
 residue
-\family default 
+\family default
  parameter is optional (you can set it to NULL) and is used to return the
  estimated power spectrum of the echo residue so it can be removed by the
  preprocessor (if you with to use it).
  
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 One important thing to keep in mind is the relationship between 
-\family typewriter 
+\family typewriter
 input_frame
-\family default 
+\family default
  and 
-\family typewriter 
+\family typewriter
 echo_frame
-\family default 
+\family default
 .
  It is important that, at any time, any echo that is present in the input
  has already been sent to the echo canceller as 
-\family typewriter 
+\family typewriter
 echo_frame
-\family default 
+\family default
 .
  In other words, the echo canceller cannot remove a signal that it hasn't
  yet received.
@@ -1280,405 +1526,557 @@
  must be small enough because otherwise part of the echo cancellation filter
  is inefficient.
  In the ideal case, you code would look like:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 write_to_soundcard(echo_frame, frame_size);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 read_from_soundcard(input_frame, frame_size);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 speex_echo_cancel(echo_state, input_frame, echo_frame, output_frame, residue);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 As stated above, if you wish to further reduce the echo present in the signal,
  you can do so by passing 
-\family typewriter 
+\family typewriter
 residue
-\family default 
+\family default
  as the last parameter of 
-\family typewriter 
+\family typewriter
 speex_preprocess()
-\family default 
+\family default
  function (see Section 
 \begin_inset LatexCommand \ref{sub:Preprocessor}
 
-\end_inset 
+\end_inset
 
 ).
-\layout Standard
+\end_layout
 
-The echo cancellation state can be destroyed as:
-\layout LyX-Code
+\begin_layout Standard
+As of version 1.2-beta1, there is an alternative, simpler API that can be
+ used instead of 
+\emph on
+speex_echo_cancel()
+\emph default
+.
+ When audio capture and playback are handled asynchronously (e.g.
+ in different threads or using the 
+\emph on
+poll()
+\emph default
+ or 
+\emph on
+select()
+\emph default
+ system call), it can be difficult to keep track of what input_frame comes
+ with what echo_frame.
+ Instead, the playback comtext/thread can simply call:
+\end_layout
 
+\begin_layout LyX-Code
+speex_echo_playback(echo_state, echo_frame);
+\end_layout
+
+\begin_layout Standard
+every time an audio frame is played.
+ Then, the capture context/thread calls:
+\end_layout
+
+\begin_layout LyX-Code
+speex_echo_capture(echo_state, input_frame, output_frame, residue);
+\end_layout
+
+\begin_layout Standard
+for every frame captured.
+ Internally, 
+\emph on
+speex_echo_playback()
+\emph default
+ simply buffers the playback frame so it can be used by 
+\emph on
+speex_echo_capture()
+\emph default
+ to call 
+\emph on
+speex_echo_cancel()
+\emph default
+.
+ When capture and playback are done synchronously, 
+\emph on
+speex_echo_cancel()
+\emph default
+ is still prefered since it gives better control on the exact input/echo
+ timing.
+\end_layout
+
+\begin_layout Standard
+The echo cancellation state can be destroyed with:
+\end_layout
+
+\begin_layout LyX-Code
 speex_echo_state_destroy(echo_state);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 It is also possible to reset the state of the echo canceller so it can be
- reused without the need to create another state as:
-\layout LyX-Code
+ reused without the need to create another state with:
+\end_layout
 
+\begin_layout LyX-Code
 speex_echo_state_reset(echo_state);
-\layout Subsubsection
+\end_layout
 
+\begin_layout Subsubsection
 Troubleshooting
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 There are several things that may prevent the echo canceller from working
  properly.
  One of them is a bug (or something suboptimal) in the code, but there are
  many others you should consider first
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Using a different soundcard to do the capture and plaback will *not* work,
  regardless of what you may think.
  The only exception to that is if the two cards can be made to have their
  sampling clock 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 locked
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  on the same clock source.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 The delay between the record and playback signals must be minimal.
  Any signal played has to 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 appear
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  on the playback (far end) signal slightly before the echo canceller 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 sees
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  it in the near end signal, but excessive delay means that part of the filter
  length is wasted.
  In the worst situations, the delay is such that it is longer than the filter
  length, in which case, no echo can be cancelled.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 When it comes to echo tail length (filter length), longer is *not* better.
  Actually, the longer the tail length, the longer it takes for the filter
  to adapt.
  Of course, a tail length that is too short will not cancel enough echo,
  but the most common problem seen is that people set a very long tail length
  and then wonder why no echo is being cancelled.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Non-linear distortion cannot (by definition) be modeled by the linear adaptive
  filter used in the echo canceller and thus cannot be cancelled.
  Use good audio gear and avoid saturation/clipping.
-\layout Subsection
+\end_layout
 
+\begin_layout Standard
+Also useful is reading 
+\emph on
+Echo Cancellation Demystified
+\emph default
+ by Alexey Frunze
+\begin_inset Foot
+status collapsed
+
+\begin_layout Standard
+http://www.embeddedstar.com/articles/2003/7/article20030720-1.html
+\end_layout
+
+\end_inset
+
+, which explains the fundamental principles of echo cancellation.
+ The details of the algorithm described in the article are different, but
+ the general ideas of echo cancellation through adaptive filters are the
+ same.
+\end_layout
+
+\begin_layout Subsection
 Codec Options (speex_*_ctl)
 \begin_inset LatexCommand \label{sub:Codec-Options}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The Speex encoder and decoder support many options and requests that can
  be accessed through the 
-\emph on 
+\emph on
 speex_encoder_ctl
-\emph default 
+\emph default
  and 
-\emph on 
+\emph on
 speex_decoder_ctl
-\emph default 
+\emph default
  functions.
  These functions are similar to the 
-\emph on 
+\emph on
 ioctl
-\emph default 
+\emph default
  system call and their prototypes are:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 void speex_encoder_ctl(void *encoder, int request, void *ptr);
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 void speex_decoder_ctl(void *encoder, int request, void *ptr);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The different values of request allowed are (note that some only apply to
  the encoder or the decoder):
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_ENH** Set perceptual enhancer
 \begin_inset LatexCommand \index{perceptual enhancement}
 
-\end_inset 
+\end_inset
 
  to on (1) or off (0) (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_ENH** Get perceptual enhancer status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_FRAME_SIZE Get the frame size used for the current mode (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_QUALITY* Set the encoder speech quality (integer 0 to 10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_QUALITY* Get the current encoder speech quality (integer 0 to
  10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_LOW_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_LOW_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_HIGH_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_HIGH_MODE*
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_VBR* Set variable bit-rate (VBR) to on (1) or off (0) (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_VBR* Get variable bit-rate
 \begin_inset LatexCommand \index{variable bit-rate}
 
-\end_inset 
+\end_inset
 
  (VBR) status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_VBR_QUALITY* Set the encoder VBR speech quality (float 0 to 10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_VBR_QUALITY* Get the current encoder VBR speech quality (float
  0 to 10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_COMPLEXITY* Set the CPU resources allowed for the encoder (integer
  1 to 10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_COMPLEXITY* Get the CPU resources allowed for the encoder (integer
  1 to 10)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_BITRATE* Set the bit-rate to use to the closest value not exceeding
  the parameter (integer in bps)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_BITRATE Get the current bit-rate in use (integer in bps)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_SAMPLING_RATE Set real sampling rate (integer in Hz)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_SAMPLING_RATE Get real sampling rate (integer in Hz)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_RESET_STATE Reset the encoder/decoder state to its original state
  (zeros all memories)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_VAD* Set voice activity detection
 \begin_inset LatexCommand \index{voice activity detection}
 
-\end_inset 
+\end_inset
 
  (VAD) to on (1) or off (0) (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_VAD* Get voice activity detection (VAD) status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_DTX* Set discontinuous transmission
 \begin_inset LatexCommand \index{discontinuous transmission}
 
-\end_inset 
+\end_inset
 
  (DTX) to on (1) or off (0) (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_DTX* Get discontinuous transmission (DTX) status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_ABR* Set average bit-rate
 \begin_inset LatexCommand \index{average bit-rate}
 
-\end_inset 
+\end_inset
 
  (ABR) to a value n in bits per second (integer in bps)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_ABR* Get average bit-rate (ABR) setting (integer in bps)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SET_PLC_TUNING* Tell the encoder to optimize encoding for a certain
  percentage of packet loss (integer in percent)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_GET_PLC_TUNING* Get the current tuning of the encoder for PLC (integer
  in percent)
-\layout Description
+\end_layout
 
+\begin_layout Description
 * applies only to the encoder
-\layout Description
+\end_layout
 
+\begin_layout Description
 ** applies only to the decoder
-\layout Description
+\end_layout
 
-
+\begin_layout Description
 \begin_inset Formula $\dagger$
-\end_inset 
+\end_inset
 
  normally only used internally
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Mode queries
 \begin_inset LatexCommand \label{sub:Mode-queries}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex modes have a query system similar to the speex_encoder_ctl and speex_decod
 er_ctl calls.
  Since modes are read-only, it is only possible to get information about
  a particular mode.
  The function used to do that is:
-\layout LyX-Code
+\end_layout
 
+\begin_layout LyX-Code
 void speex_mode_query(SpeexMode *mode, int request, void *ptr);
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The admissible values for request are (unless otherwise note, the values
  are returned through 
-\emph on 
+\emph on
 ptr
-\emph default 
+\emph default
 ):
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_MODE_FRAME_SIZE Get the frame size (in samples) for the mode
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_SUBMODE_BITRATE Get the bit-rate for a submode number specified through
  
-\emph on 
+\emph on
 ptr
-\emph default 
+\emph default
  (integer in bps).
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Preprocessor options
 \begin_inset LatexCommand \label{sub:Preprocessor-options}
 
-\end_inset 
+\end_inset
 
 
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_DENOISE Turns denoising on(1) or off(2) (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_DENOISE Get denoising status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_AGC Turns automatic gain control (AGC) on(1) or off(2)
  (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_AGC Get AGC status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_VAD Turns voice activity detector (VAD) on(1) or off(2)
  (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_VAD Get VAD status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_AGC_LEVEL
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_AGC_LEVEL
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_DEREVERB Turns reverberation removal on(1) or off(2)
  (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_DEREVERB Get reverberation removal status (integer)
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_DEREVERB_LEVEL
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_DEREVERB_LEVEL
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_SET_DEREVERB_DECAY
-\layout Description
+\end_layout
 
+\begin_layout Description
 SPEEX_PREPROCESS_GET_DEREVERB_DECAY
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Packing and in-band signalling
 \begin_inset LatexCommand \index{in-band signalling}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Sometimes it is desirable to pack more than one frame per packet (or other
  basic unit of storage).
  The proper way to do it is to call speex_encode 
 \begin_inset Formula $N$
-\end_inset 
+\end_inset
 
  times before writing the stream with speex_bits_write.
  In cases where the number of frames is not determined by an out-of-band
@@ -1687,55 +2085,55 @@
  as shown in Table 
 \begin_inset LatexCommand \ref{cap:quality_vs_bps}
 
-\end_inset 
+\end_inset
 
 .
  Note that as of version 1.0.2, calling speex_bits_write automatically inserts
  the terminator so as to fill the last byte.
  This doesn't involves any overhead and makes sure Speex can always detect
  when there is no more frame in a packet.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 It is also possible to send in-band 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 messages
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  to the other side.
  All these messages are encoded as 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 pseudo-frames
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  of mode 14 which contain a 4-bit message type code, followed by the message.
  Table 
 \begin_inset LatexCommand \ref{cap:In-band-signalling-codes}
 
-\end_inset 
+\end_inset
 
  lists the available codes, their meaning and the size of the message that
  follows.
  Most of these messages are requests that are sent to the encoder or decoder
  on the other end, which is free to comply or ignore them.
  By default, all in-band messages are ignored.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Float table
 placement htbp
 wide false
-collapsed false
+sideways false
+status open
 
-\layout Standard
-
-
-\begin_inset  Tabular
+\begin_layout Standard
+\begin_inset Tabular
 <lyxtabular version="3" rows="17" columns="3">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
@@ -1745,673 +2143,746 @@
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Code
+\end_layout
 
-Code
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Size (bits)
+\end_layout
 
-Size (bits)
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Content
+\end_layout
 
-Content
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks decoder to set perceptual enhancement off (0) or on(1)
+\end_layout
 
-Asks decoder to set perceptual enhancement off (0) or on(1)
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
-
+\begin_layout Standard
 Asks (if 1) the encoder to be less 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 agressive
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  due to high packet loss
-\end_inset 
+\end_layout
+
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+2
+\end_layout
 
-2
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks encoder to switch to mode N
+\end_layout
 
-Asks encoder to switch to mode N
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks encoder to switch to mode N for low-band
+\end_layout
 
-Asks encoder to switch to mode N for low-band
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks encoder to switch to mode N for high-band
+\end_layout
 
-Asks encoder to switch to mode N for high-band
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+5
+\end_layout
 
-5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks encoder to switch to quality N for VBR
+\end_layout
 
-Asks encoder to switch to quality N for VBR
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+6
+\end_layout
 
-6
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Request acknowloedge (0=no, 1=all, 2=only for in-band data)
+\end_layout
 
-Request acknowloedge (0=no, 1=all, 2=only for in-band data)
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+7
+\end_layout
 
-7
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Asks encoder to set CBR (0), VAD(1), DTX(3), VBR(5), VBR+DTX(7)
+\end_layout
 
-Asks encoder to set CBR (0), VAD(1), DTX(3), VBR(5), VBR+DTX(7)
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Transmit (8-bit) character to the other end
+\end_layout
 
-Transmit (8-bit) character to the other end
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+9
+\end_layout
 
-9
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Intensity stereo information
+\end_layout
 
-Intensity stereo information
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+10
+\end_layout
 
-10
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+16
+\end_layout
 
-16
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Announce maximum bit-rate acceptable (N in bytes/second)
+\end_layout
 
-Announce maximum bit-rate acceptable (N in bytes/second)
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+11
+\end_layout
 
-11
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+16
+\end_layout
 
-16
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+12
+\end_layout
 
-12
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+32
+\end_layout
 
-32
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Acknowledge receiving packet N
+\end_layout
 
-Acknowledge receiving packet N
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+13
+\end_layout
 
-13
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+32
+\end_layout
 
-32
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+14
+\end_layout
 
-14
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+64
+\end_layout
 
-64
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true" bottomline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+15
+\end_layout
 
-15
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+64
+\end_layout
 
-64
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 </lyxtabular>
 
-\end_inset 
+\end_inset
 
 
-\layout Caption
+\end_layout
 
+\begin_layout Caption
 In-band signalling codes
 \begin_inset LatexCommand \label{cap:In-band-signalling-codes}
 
-\end_inset 
+\end_inset
 
 
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Standard
 
+\end_layout
+
+\begin_layout Standard
 Finally, applications may define custom in-band messages using mode 13.
  The size of the message in bytes is encoded with 5 bits, so that the decoder
  can skip it if it doesn't know how to interpret it.
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Formats and standards
 \begin_inset LatexCommand \index{standards}
 
-\end_inset 
+\end_inset
 
 
 \begin_inset LatexCommand \label{sec:Formats-and-standards}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex can encode speech in both narrowband and wideband and provides different
  bit-rates.
  However, not all features need to be supported by a certain implementation
  or device.
  In order to be called 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 Speex compatible
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  (whatever that means), an implementation must implement at least a basic
  set of features.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 At the minimum, all narrowband modes of operation MUST be supported at the
  decoder.
  This includes the decoding of a wideband bit-stream by the narrowband decoder
 \begin_inset Foot
-collapsed true
+status collapsed
 
-\layout Standard
-
+\begin_layout Standard
 The wideband bit-stream contains an embedded narrowband bit-stream which
  can be decoded alone
-\end_inset 
+\end_layout
 
+\end_inset
+
 .
  If present, a wideband decoder MUST be able to decode a narrowband stream,
  and MAY either be able to decode all wideband modes or be able to decode
  the embedded narrowband part of all modes (which includes ignoring the
  high-band bits).
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For encoders, at least one narrowband or wideband mode MUST be supported.
  The main reason why all encoding modes do not have to be supported is that
  some platforms may not be able to handle the complexity of encoding in
  some modes.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 RTP
 \begin_inset LatexCommand \index{RTP}
 
-\end_inset 
+\end_inset
 
  Payload Format 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The RTP payload draft is included in appendix 
 \begin_inset LatexCommand \ref{sec:IETF-draft}
 
-\end_inset 
+\end_inset
 
  and the latest version is available at 
 \begin_inset LatexCommand \url{http://www.speex.org/drafts/latest}
 
-\end_inset 
+\end_inset
 
 .
  This draft has been sent (2003/02/26) to the Internet Engineering Task
  Force (IETF) and will be discussed at the March 18th meeting in San Francisco.
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 MIME Type
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For now, you should use the MIME type audio/x-speex for Speex-in-Ogg.
  We will apply for type 
-\family typewriter 
+\family typewriter
 audio/speex
-\family default 
+\family default
  in the near future.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Ogg
 \begin_inset LatexCommand \index{Ogg}
 
-\end_inset 
+\end_inset
 
  file format
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex bit-streams can be stored in Ogg files.
  In this case, the first packet of the Ogg file contains the Speex header
  described in table 
 \begin_inset LatexCommand \ref{cap:ogg_speex_header}
 
-\end_inset 
+\end_inset
 
 .
  All integer fields in the headers are stored as little-endian.
  The 
-\family typewriter 
+\family typewriter
 speex_string
-\family default 
+\family default
  field must contain the 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 
-\family typewriter 
+\family typewriter
 Speex
-\family default 
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
+\family default
+\InsetSpace ~
+\InsetSpace ~
+\InsetSpace ~
 
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  (with 3 trailing spaces), which identifies the bit-stream.
  The next field, 
-\family typewriter 
+\family typewriter
 speex_version
-\family default 
+\family default
  contains the version of Speex that encoded the file.
  For now, refer to speex_header.[ch] for more info.
  The 
-\emph on 
+\emph on
 beginning of stream
-\emph default 
+\emph default
  (
-\family typewriter 
+\family typewriter
 b_o_s
-\family default 
+\family default
 ) flag is set to 1 for the header.
  The header packet has 
-\family typewriter 
+\family typewriter
 packetno=0
-\family default 
+\family default
  and 
-\family typewriter 
+\family typewriter
 granulepos=0
-\family default 
+\family default
 .
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The second packet contains the Speex comment header.
  The format used is the Vorbis comment format described here: http://www.xiph.org/
 ogg/vorbis/doc/v-comment.html .
  This packet has 
-\family typewriter 
+\family typewriter
 packetno=1
-\family default 
+\family default
  and 
-\family typewriter 
+\family typewriter
 granulepos=0
-\family default 
+\family default
 .
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The third and subsequent packets each contain one or more (number found
  in header) Speex frames.
  These are identified with 
-\family typewriter 
+\family typewriter
 packetno
-\family default 
+\family default
  starting from 2 and the 
-\family typewriter 
+\family typewriter
 granulepos
-\family default 
+\family default
  is the number of the last sample encoded in that packet.
  The last of these packets has the 
-\emph on 
+\emph on
 end of stream
-\emph default 
+\emph default
  (
-\family typewriter 
+\family typewriter
 e_o_s
-\family default 
+\family default
 ) flag is set to 1.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Float table
 placement htbp
 wide true
-collapsed false
+sideways false
+status open
 
-\layout Standard
-
-
-\begin_inset  Tabular
+\begin_layout Standard
+\begin_inset Tabular
 <lyxtabular version="3" rows="16" columns="3">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
@@ -2421,584 +2892,652 @@
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Field
+\end_layout
 
-Field
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Type
+\end_layout
 
-Type
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Size
+\end_layout
 
-Size
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+speex_string
+\end_layout
 
-speex_string
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+char[]
+\end_layout
 
-char[]
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+speex_version
+\end_layout
 
-speex_version
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+char[]
+\end_layout
 
-char[]
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+20
+\end_layout
 
-20
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+speex_version_id
+\end_layout
 
-speex_version_id
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+header_size
+\end_layout
 
-header_size
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+rate
+\end_layout
 
-rate
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+mode
+\end_layout
 
-mode
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+mode_bitstream_version
+\end_layout
 
-mode_bitstream_version
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+nb_channels
+\end_layout
 
-nb_channels
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+bitrate
+\end_layout
 
-bitrate
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame_size
+\end_layout
 
-frame_size
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+vbr
+\end_layout
 
-vbr
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frames_per_packet
+\end_layout
 
-frames_per_packet
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+extra_headers
+\end_layout
 
-extra_headers
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved1
+\end_layout
 
-reserved1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true" bottomline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved2
+\end_layout
 
-reserved2
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+int
+\end_layout
 
-int
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 </lyxtabular>
 
-\end_inset 
+\end_inset
 
 
-\layout Caption
+\end_layout
 
+\begin_layout Caption
 Ogg/Speex header packet
 \begin_inset LatexCommand \label{cap:ogg_speex_header}
 
-\end_inset 
+\end_inset
 
 
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Section
-\pagebreak_top 
+
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Introduction to CELP Coding
 \begin_inset LatexCommand \index{CELP}
 
-\end_inset 
+\end_inset
 
 
 \begin_inset LatexCommand \label{sec:Introduction-to-CELP}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex is based on CELP, which stands for Code Excited Linear Prediction.
  This section attempts to introduce the principles behind CELP, so if you
  are already familiar with CELP, you can safely skip to section 
 \begin_inset LatexCommand \ref{sec:Speex-narrowband-mode}
 
-\end_inset 
+\end_inset
 
 .
  The CELP technique is based on three ideas:
-\layout Enumerate
+\end_layout
 
+\begin_layout Enumerate
 The use of a linear prediction (LP) model to model the vocal tract
-\layout Enumerate
+\end_layout
 
+\begin_layout Enumerate
 The use of (adaptive and fixed) codebook entries as input (excitation) of
  the LP model
-\layout Enumerate
+\end_layout
 
+\begin_layout Enumerate
 The search performed in closed-loop in a 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 perceptually weighted domain
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This section describes the basic ideas behind CELP.
  Note that it's still incomplete.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Linear Prediction (LPC)
 \begin_inset LatexCommand \index{linear prediction}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Linear prediction is at the base of many speech coding techniques, including
  CELP.
  The idea behind it is to predict the signal 
 \begin_inset Formula $x[n]$
-\end_inset 
+\end_inset
 
  using a linear combination of its past samples:
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 y[n]=\sum_{i=1}^{N}a_{i}x[n-i]\]
 
-\end_inset 
+\end_inset
 
 where 
 \begin_inset Formula $y[n]$
-\end_inset 
+\end_inset
 
  is the linear prediction of 
 \begin_inset Formula $x[n]$
-\end_inset 
+\end_inset
 
 .
  The prediction error is thus given by:
 \begin_inset Formula \[
 e[n]=x[n]-y[n]=x[n]-\sum_{i=1}^{N}a_{i}x[n-i]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The goal of the LPC analysis is to find the best prediction coefficients
  
 \begin_inset Formula $a_{i}$
-\end_inset 
+\end_inset
 
  which minimize the quadratic error function:
 \begin_inset Formula \[
 E=\sum_{n=0}^{L-1}\left[e[n]\right]^{2}=\sum_{n=0}^{L-1}\left[x[n]-\sum_{i=1}^{N}a_{i}x[n-i]\right]^{2}\]
 
-\end_inset 
+\end_inset
 
 That can be done by making all derivatives 
 \begin_inset Formula $\frac{\partial E}{\partial a_{i}}$
-\end_inset 
+\end_inset
 
  equal to zero:
 \begin_inset Formula \[
 \frac{\partial E}{\partial a_{i}}=\frac{\partial}{\partial a_{i}}\sum_{n=0}^{L-1}\left[x[n]-\sum_{i=1}^{N}a_{i}x[n-i]\right]^{2}=0\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The 
 \begin_inset Formula $a_{i}$
-\end_inset 
+\end_inset
 
  filter coefficients are computed using the Levinson-Durbin
 \begin_inset LatexCommand \index{Levinson-Durbin}
 
-\end_inset 
+\end_inset
 
  algorithm, which starts from the auto-correlation
 \begin_inset LatexCommand \index{auto-correlation}
 
-\end_inset 
+\end_inset
 
  
 \begin_inset Formula $R(m)$
-\end_inset 
+\end_inset
 
  of the signal 
 \begin_inset Formula $x[n]$
-\end_inset 
+\end_inset
 
 .
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 R(m)=\sum_{i=0}^{N-1}x[i]x[i-m]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For an order 
 \begin_inset Formula $N$
-\end_inset 
+\end_inset
 
  filter, we have:
 \begin_inset Formula \[
@@ -3008,7 +3547,7 @@
 \vdots & \vdots & \ddots & \vdots\\
 R(N-1) & R(N-2) & \cdots & R(0)\end{array}\right]\]
 
-\end_inset 
+\end_inset
 
 
 \begin_inset Formula \[
@@ -3018,301 +3557,325 @@
 \vdots\\
 R(N)\end{array}\right]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The filter coefficients 
 \begin_inset Formula $a_{i}$
-\end_inset 
+\end_inset
 
  are found by solving the system 
 \begin_inset Formula $\mathbf{Ra}=\mathbf{r}$
-\end_inset 
+\end_inset
 
 .
  What the Levinson-Durbin algorithm does here is making the solution to
  the problem 
 \begin_inset Formula $\mathcal{O}\left(N^{2}\right)$
-\end_inset 
+\end_inset
 
  instead of 
 \begin_inset Formula $\mathcal{O}\left(N^{3}\right)$
-\end_inset 
+\end_inset
 
  by exploiting the fact that matrix 
 \begin_inset Formula $\mathbf{R}$
-\end_inset 
+\end_inset
 
  is toeplitz hermitian.
  Also, it can be proven that all the roots of 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  are within the unit circle, which means that 
 \begin_inset Formula $1/A(z)$
-\end_inset 
+\end_inset
 
  is always stable.
  This is in theory; in practice because of finite precision, there are two
  commonly used techniques to make sure we have a stable filter.
  First, we multiply 
 \begin_inset Formula $R(0)$
-\end_inset 
+\end_inset
 
  by a number slightly above one (such as 1.0001), which is equivalent to
  adding noise to the signal.
  Also, we can apply a window to the auto-correlation, which is equivalent
  to filtering in the frequency domain, reducing sharp resonances.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The linear prediction model represents each speech sample as a linear combinatio
 n of past samples, plus an error signal called the excitation (or residual).
 \begin_inset Formula \[
 x[n]=\sum_{i=1}^{N}a_{i}x[n-i]+e[n]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In the 
-\emph on 
+\emph on
 z
-\emph default 
+\emph default
 -domain, this can be expressed as
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 x(z)=\frac{1}{A(z)}\: e(z)\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  is defined as
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 A(z)=1-\sum_{i=1}^{N}a_{i}z^{-i}\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 We usually refer to 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  as the analysis filter and 
 \begin_inset Formula $1/A(z)$
-\end_inset 
+\end_inset
 
  as the synthesis filter.
  The whole process is called short-term prediction as it predicts the signal
  
 \begin_inset Formula $x[n]$
-\end_inset 
+\end_inset
 
  using a prediction using only the 
 \begin_inset Formula $N$
-\end_inset 
+\end_inset
 
  past samples, where 
 \begin_inset Formula $N$
-\end_inset 
+\end_inset
 
  is usually around 10.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Because LPC coefficients have very little robustness to quantization, they
  are converted to Line Spectral Pair
 \begin_inset LatexCommand \index{line spectral pair}
 
-\end_inset 
+\end_inset
 
  (LSP) coefficients which have a much better behaviour with quantization,
  one of them being that it's easy to keep the filter stable.
  
-\layout Comment
+\end_layout
 
+\begin_layout Standard
+\begin_inset Note Comment
+status collapsed
+
+\begin_layout Standard
 Describe LSP's
-\layout Subsection
+\end_layout
 
+\end_inset
+
+
+\end_layout
+
+\begin_layout Subsection
 Pitch Prediction
 \begin_inset LatexCommand \index{pitch}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 During voiced segments, the speech signal is periodic, so it is possible
  to take advantage of that property by approximating the excitation signal
  
 \begin_inset Formula $e[n]$
-\end_inset 
+\end_inset
 
  by a gain times the past of the excitation:
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 e[n]\simeq p[n]=\beta e[n-T]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
 \begin_inset Formula $T$
-\end_inset 
+\end_inset
 
  is the pitch period, 
 \begin_inset Formula $\beta$
-\end_inset 
+\end_inset
 
  is the pitch gain.
  We call that long-term prediction since the excitation is predicted from
  
 \begin_inset Formula $e[n-T]$
-\end_inset 
+\end_inset
 
  with 
 \begin_inset Formula $T\gg N$
-\end_inset 
+\end_inset
 
 .
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Innovation Codebook
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The final excitation 
 \begin_inset Formula $e[n]$
-\end_inset 
+\end_inset
 
  will be the sum of the pitch prediction and an 
-\emph on 
+\emph on
 innovation
-\emph default 
+\emph default
  signal 
 \begin_inset Formula $c[n]$
-\end_inset 
+\end_inset
 
  taken from a fixed codebook, hence the name 
-\emph on 
+\emph on
 Code
-\emph default 
+\emph default
  Excited Linear Prediction.
  The final excitation is given by:
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \[
 e[n]=p[n]+c[n]=\beta e[n-T]+c[n]\]
 
-\end_inset 
+\end_inset
 
 The quantization of 
 \begin_inset Formula $c[n]$
-\end_inset 
+\end_inset
 
  is where most of the bits in a CELP codec are allocated.
  It represents the information that couldn't be obtained either from linear
  prediction or pitch prediction.
  In the 
-\emph on 
+\emph on
 z
-\emph default 
+\emph default
 -domain we can represent the final signal 
 \begin_inset Formula $X(z)$
-\end_inset 
+\end_inset
 
  as 
 \begin_inset Formula \[
 X(z)=\frac{C(z)}{A(z)\left(1-\beta z^{-T}\right)}\]
 
-\end_inset 
+\end_inset
 
 
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Analysis-by-Synthesis and Error Weighting
 \begin_inset LatexCommand \index{error weighting}
 
-\end_inset 
+\end_inset
 
 
 \begin_inset LatexCommand \index{analysis-by-synthesis}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Most (if not all) modern audio codecs attempt to 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 shape
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  the noise so that it appears mostly in the frequency regions where the
  ear cannot detect it.
  For example, the ear is more tolerant to noise in parts of the spectrum
  that are louder and 
-\emph on 
+\emph on
 vice versa
-\emph default 
+\emph default
 .
  That's why instead of minimizing the simple quadratic error
 \begin_inset Formula \[
 E=\sum_{n}\left(x[n]-\overline{x}[n]\right)^{2}\]
 
-\end_inset 
+\end_inset
 
 where 
 \begin_inset Formula $\overline{x}[n]$
-\end_inset 
+\end_inset
 
  is the encoder signal, we minimize the error for the perceptually weighted
  signal
 \begin_inset Formula \[
 X_{w}(z)=W(z)X(z)\]
 
-\end_inset 
+\end_inset
 
 where 
 \begin_inset Formula $W(z)$
-\end_inset 
+\end_inset
 
  is the weighting filter, usually of the form
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Formula \begin{equation}
 W(z)=\frac{A\left(\frac{z}{\gamma_{1}}\right)}{A\left(\frac{z}{\gamma_{2}}\right)}\label{eq:weighting_filter}\end{equation}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 with control parameters 
 \begin_inset Formula $\gamma_{1}>\gamma_{2}$
-\end_inset 
+\end_inset
 
 .
  If the noise is white in the perceptually weighted domain, then in the
@@ -3320,126 +3883,143 @@
 \begin_inset Formula \[
 A_{noise}(z)=\frac{1}{W(z)}=\frac{A\left(\frac{z}{\gamma_{2}}\right)}{A\left(\frac{z}{\gamma_{1}}\right)}\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If a filter 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  has (complex) poles at 
 \begin_inset Formula $p_{i}$
-\end_inset 
+\end_inset
 
  in the 
 \begin_inset Formula $z$
-\end_inset 
+\end_inset
 
 -plane, the filter 
 \begin_inset Formula $A(z/\gamma)$
-\end_inset 
+\end_inset
 
  will have its poles at 
 \begin_inset Formula $p'_{i}=\gamma p_{i}$
-\end_inset 
+\end_inset
 
 , making it a flatter version of 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
 .
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Analysis-by-synthesis refers to the fact that when trying to find the best
  pitch parameters (
 \begin_inset Formula $T$
-\end_inset 
+\end_inset
 
 , 
 \begin_inset Formula $\beta$
-\end_inset 
+\end_inset
 
 ) and innovation signal 
 \begin_inset Formula $c[n]$
-\end_inset 
+\end_inset
 
 , we do not work by making the excitation 
 \begin_inset Formula $e[n]$
-\end_inset 
+\end_inset
 
  as close as the original one (which would be simpler), but apply the synthesis
  (and weighting) filter and try making 
 \begin_inset Formula $X_{w}(z)$
-\end_inset 
+\end_inset
 
  as close to the original as possible.
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Speex narrowband mode
 \begin_inset LatexCommand \label{sec:Speex-narrowband-mode}
 
-\end_inset 
+\end_inset
 
 
 \begin_inset LatexCommand \index{narrowband}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This section looks at how Speex works for narrowband (
 \begin_inset Formula $8\:\mathrm{kHz}$
-\end_inset 
+\end_inset
 
  sampling rate) operation.
  The frame size for this mode is 
 \begin_inset Formula $20\:\mathrm{ms}$
-\end_inset 
+\end_inset
 
 , corresponding to 160 samples.
  Each frame is also subdivided into 4 sub-frames of 40 samples each.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Also many design decisions were based on the original goals and assumptions:
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Minimizing the amount of information extracted from past frames (for robustness
  to packet loss)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Dynamically-selectable codebooks (LSP, pitch and innovation)
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 sub-vector fixed (innovation) codebooks
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 LPC Analysis
 \begin_inset LatexCommand \index{linear prediction}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 An LPC analysis is first performed on a (asymetric Hamming) window that
  spans all of the current frame and half a frame in advance.
  The LPC coefficients are then converted to Line Spectral Pair
 \begin_inset LatexCommand \index{line spectral pair}
 
-\end_inset 
+\end_inset
 
  (LSP), a representation that is more robust to quantization.
  The LSP's are considered to be associated to the 
 \begin_inset Formula $4^{th}$
-\end_inset 
+\end_inset
 
  sub-frames and the LSP's associated to the first 3 sub-frames are linearly
  interpolated using the current and previous LSP's.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The LSP's are encoded using 30 bits for higher quality modes and 18 bits
  for lower quality, through the use of a multi-stage split-vector quantizer.
  For the lower quality modes, the 10 coefficients are first quantized with
@@ -3447,102 +4027,108 @@
  Each of them is quantized with 6 bits, for a total of 18 bits.
  For the higher quality modes, the remaining error on both sub-vectors is
  further quantized with 6 bits each, for a total of 30 bits.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The perceptual weighting filter 
 \begin_inset Formula $W(z)$
-\end_inset 
+\end_inset
 
  used by Speex is derived from the LPC filter 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  and corresponds to the one described by eq.
  
 \begin_inset LatexCommand \ref{eq:weighting_filter}
 
-\end_inset 
+\end_inset
 
  with 
 \begin_inset Formula $\gamma_{1}=0.9$
-\end_inset 
+\end_inset
 
  and 
 \begin_inset Formula $\gamma_{2}=0.6$
-\end_inset 
+\end_inset
 
 .
  We can use the unquantized 
 \begin_inset Formula $A(z)$
-\end_inset 
+\end_inset
 
  filter since the weighting filter is only used in the encoder.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Pitch Prediction (adaptive codebook)
 \begin_inset LatexCommand \index{pitch}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex uses a 3-tap prediction for pitch.
  That is, the pitch prediction signal 
 \begin_inset Formula $p[n]$
-\end_inset 
+\end_inset
 
  is obtained by the past of the excitation by:
 \begin_inset Formula \[
 p[n]=\beta_{0}e[n-T-1]+\beta_{1}e[n-T]+\beta_{2}e[n-T+1]\]
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 where 
 \begin_inset Formula $T$
-\end_inset 
+\end_inset
 
  is the pitch period and the 
 \begin_inset Formula $\beta_{i}$
-\end_inset 
+\end_inset
 
  are the prediction (filter) taps.
  It is worth noting that when the pitch is smaller than the sub-frame size,
  we repeat the excitation at a period 
 \begin_inset Formula $T$
-\end_inset 
+\end_inset
 
 .
  For example, when 
 \begin_inset Formula $n-T+1$
-\end_inset 
+\end_inset
 
 , we use 
 \begin_inset Formula $n-2T+1$
-\end_inset 
+\end_inset
 
  instead.
  The period and quantized gains are determined in closed loop (analysis-by-synth
 esis).
  In most modes, the pitch period is encoded with 7 bits in the 
 \begin_inset Formula $\left[17,144\right]$
-\end_inset 
+\end_inset
 
  range and the 
 \begin_inset Formula $\beta_{i}$
-\end_inset 
+\end_inset
 
  coefficients are vector-quantized using 7 bits (15 kbps narrowband and
  above) at higher bit-rates and 5 bits at lower bit-rates (11 kbps narrowband
  and below).
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Innovation Codebook
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In Speex, the innovation signal is quantized using sub-vector shape-only
  vector quantization (VQ).
  That means that the innovation signal is divided in sub-vectors (of size
@@ -3551,18 +4137,20 @@
  This saves many bits that would otherwise be allocated for a separate gain
  at the price of a slight increase in complexity.
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Bit allocation
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 There are 7 different narrowband bit-rates defined for Speex, ranging from
  250 bps to 24.6 kbps, although the modes below 5.9 kbps should not be used
  for speech.
  The bit-allocation for each mode is detailed in table 
 \begin_inset LatexCommand \ref{cap:bits-narrowband}
 
-\end_inset 
+\end_inset
 
 .
  Each frame starts with the mode ID encoded with 4 bits which allows a range
@@ -3574,26 +4162,25 @@
  sub-frame is packed.
  Note that the 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 OL
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  in the parameter description means that the parameter is an open loop estimatio
 n based on the whole frame.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Float table
 placement h
 wide true
-collapsed false
+sideways false
+status open
 
-\layout Standard
-
-
-\begin_inset  Tabular
+\begin_layout Standard
+\begin_inset Tabular
 <lyxtabular version="3" rows="12" columns="11">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
@@ -3611,1110 +4198,1246 @@
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Parameter
+\end_layout
 
-Parameter
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Update rate
+\end_layout
 
-Update rate
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+2
+\end_layout
 
-2
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+5
+\end_layout
 
-5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+6
+\end_layout
 
-6
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+7
+\end_layout
 
-7
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Wideband bit
+\end_layout
 
-Wideband bit
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Mode ID
+\end_layout
 
-Mode ID
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+LSP
+\end_layout
 
-LSP
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18
+\end_layout
 
-18
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18
+\end_layout
 
-18
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18
+\end_layout
 
-18
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18
+\end_layout
 
-18
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+30
+\end_layout
 
-30
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+30
+\end_layout
 
-30
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+30
+\end_layout
 
-30
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18
+\end_layout
 
-18
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+OL pitch
+\end_layout
 
-OL pitch
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+7
+\end_layout
 
-7
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+7
+\end_layout
 
-7
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
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 </row>
 </lyxtabular>
 
-\end_inset 
+\end_inset
 
 
-\layout Caption
+\end_layout
 
+\begin_layout Caption
 Bit allocation for narrowband modes
 \begin_inset LatexCommand \label{cap:bits-narrowband}
 
-\end_inset 
+\end_inset
 
 
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Standard
 
+\end_layout
+
+\begin_layout Standard
 So far, no MOS (Mean Opinion Score
 \begin_inset LatexCommand \index{mean opinion score}
 
-\end_inset 
+\end_inset
 
 ) subjective evaluation has been performed for Speex.
  In order to give an idea of the quality achivable with it, table 
 \begin_inset LatexCommand \ref{cap:quality_vs_bps}
 
-\end_inset 
+\end_inset
 
  presents my own subjective opinion on it.
  It sould be noted that different people will perceive the quality differently
@@ -4727,21 +5450,20 @@
  Decoding requires approximately 0.5 mflops
 \begin_inset LatexCommand \index{complexity}
 
-\end_inset 
+\end_inset
 
  in most modes (1 mflops with perceptual enhancement).
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+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Float table
 placement h
 wide true
-collapsed false
+sideways false
+status open
 
-\layout Standard
-
-
-\begin_inset  Tabular
+\begin_layout Standard
+\begin_inset Tabular
 <lyxtabular version="3" rows="17" columns="4">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
@@ -4752,616 +5474,689 @@
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-\layout Standard
-
+\begin_layout Standard
 Bit-rate
 \begin_inset LatexCommand \index{bit-rate}
 
-\end_inset 
+\end_inset
 
  (bps)
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+
+\end_inset
 </cell>
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+\begin_layout Standard
 mflops
 \begin_inset LatexCommand \index{complexity}
 
-\end_inset 
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-\end_inset 
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+
+\end_inset
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 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+2
+\end_layout
 
-2
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
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-5,950
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
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-9
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Very noticeable artifacts/noise, good intelligibility
+\end_layout
 
-Very noticeable artifacts/noise, good intelligibility
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8,000
+\end_layout
 
-8,000
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+10
+\end_layout
 
-10
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Artifacts/noise sometimes noticeable
+\end_layout
 
-Artifacts/noise sometimes noticeable
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+11,000
+\end_layout
 
-11,000
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+14
+\end_layout
 
-14
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Artifacts usually noticeable only with headphones
+\end_layout
 
-Artifacts usually noticeable only with headphones
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+5
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-5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+15,000
+\end_layout
 
-15,000
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+11
+\end_layout
 
-11
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Need good headphones to tell the difference
+\end_layout
 
-Need good headphones to tell the difference
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+6
+\end_layout
 
-6
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+18,200
+\end_layout
 
-18,200
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+17.5
+\end_layout
 
-17.5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Hard to tell the difference even with good headphones
+\end_layout
 
-Hard to tell the difference even with good headphones
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+7
+\end_layout
 
-7
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+24,600
+\end_layout
 
-24,600
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+14.5
+\end_layout
 
-14.5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Completely transparent for voice, good quality music
+\end_layout
 
-Completely transparent for voice, good quality music
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+8
+\end_layout
 
-8
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3,950
+\end_layout
 
-3,950
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+10.5
+\end_layout
 
-10.5
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Very noticeable artifacts/noise, good intelligibility
+\end_layout
 
-Very noticeable artifacts/noise, good intelligibility
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+9
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-9
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
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-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
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+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+10
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-10
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+11
+\end_layout
 
-11
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+12
+\end_layout
 
-12
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+reserved
+\end_layout
 
-reserved
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+13
+\end_layout
 
-13
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Application-defined, interpreted by callback or skipped
+\end_layout
 
-Application-defined, interpreted by callback or skipped
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+14
+\end_layout
 
-14
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Speex in-band signaling
+\end_layout
 
-Speex in-band signaling
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true" bottomline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+15
+\end_layout
 
-15
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+N/A
+\end_layout
 
-N/A
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Terminator code
+\end_layout
 
-Terminator code
-\end_inset 
+\end_inset
 </cell>
 </row>
 </lyxtabular>
 
-\end_inset 
+\end_inset
 
 
-\layout Caption
+\end_layout
 
+\begin_layout Caption
 Quality versus bit-rate
 \begin_inset LatexCommand \label{cap:quality_vs_bps}
 
-\end_inset 
+\end_inset
 
 
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Subsection
 
+\end_layout
+
+\begin_layout Subsection
 Perceptual enhancement
 \begin_inset LatexCommand \index{perceptual enhancement}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This part of the codec only applies to the decoder and can even be changed
  without affecting inter-operability.
  For that reason, the implementation provided and described here should
@@ -5369,65 +6164,73 @@
  The enhancement system is divided into two parts.
  First, the synthesis filter 
 \begin_inset Formula $S(z)=1/A(z)$
-\end_inset 
+\end_inset
 
  is replaced by an enhanced filter
 \begin_inset Formula \[
 S'(z)=\frac{A\left(z/a_{2}\right)A\left(z/a_{3}\right)}{A\left(z\right)A\left(z/a_{1}\right)}\]
 
-\end_inset 
+\end_inset
 
 where 
 \begin_inset Formula $a_{1}$
-\end_inset 
+\end_inset
 
  and 
 \begin_inset Formula $a_{2}$
-\end_inset 
+\end_inset
 
  depend on the mode in use and 
 \begin_inset Formula $a_{3}=\frac{1}{r}\left(1-\frac{1-ra_{1}}{1-ra_{2}}\right)$
-\end_inset 
+\end_inset
 
  with 
 \begin_inset Formula $r=.9$
-\end_inset 
+\end_inset
 
 .
  The second part of the enhancement consists of using a comb filter to enhance
  the pitch in the excitation domain.
  
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Speex wideband mode (sub-band CELP)
 \begin_inset LatexCommand \index{wideband}
 
-\end_inset 
+\end_inset
 
 
 \begin_inset LatexCommand \label{sec:Speex-wideband-mode}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For wideband, the Speex approach uses a 
-\emph on 
+\emph on
 q
-\emph default 
+\emph default
 uadrature 
-\emph on 
+\emph on
 m
-\emph default 
+\emph default
 irror 
-\emph on 
+\emph on
 f
-\emph default 
+\emph default
 ilter
 \begin_inset LatexCommand \index{quadrature mirror filter}
 
-\end_inset 
+\end_inset
 
  (QMF) to split the band in two.
  The 16 kHz signal is thus divided into two 8 kHz signals, one representing
@@ -5435,35 +6238,39 @@
  The low band is encoded with the narrowband mode described in section 
 \begin_inset LatexCommand \ref{sec:Speex-narrowband-mode}
 
-\end_inset 
+\end_inset
 
  in such a way that the resulting 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 embedded narrowband bit-stream
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  can also be decoded with the narrowband decoder.
  Since the low band encoding has already been described, only the high band
  encoding is described in this section.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Linear Prediction
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The linear prediction part used for the high-band is very similar to what
  is done for narrowband.
  The only difference is that we use only 12 bits to encode the high-band
  LSP's using a multi-stage vector quantizer (MSVQ).
  The first level quantizes the 10 coefficients with 6 bits and the error
  is then quantized using 6 bits, too.
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Pitch Prediction
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 That part is easy: there's no pitch prediction for the high-band.
  There are two reasons for that.
  First, there is usually little harmonic structure in this band (above 4
@@ -5472,48 +6279,51 @@
  kHz band into 4-0 kHz (reversing the frequency axis), which means that
  the location of the harmonics is no longer at multiples of the fundamental
  (pitch).
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Excitation Quantization
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The high-band excitation is coded in the same way as for narrowband.
  
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 Bit allocation
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For the wideband mode, the entire narrowband frame is packed before the
  high-band is encoded.
  The narrowband part of the bit-stream is as defined in table 
 \begin_inset LatexCommand \ref{cap:bits-narrowband}
 
-\end_inset 
+\end_inset
 
 .
  The high-band follows, as described in table 
 \begin_inset LatexCommand \ref{cap:bits-wideband}
 
-\end_inset 
+\end_inset
 
 .
  This also means that a wideband frame may be correctly decoded by a narrowband
  decoder with the only caveat that if more than one frame is packed in the
  same packet, the decoder will need to skip the high-band parts in order
  to sync with the bit-stream.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Float table
 placement h
 wide true
-collapsed false
+sideways false
+status open
 
-\layout Standard
-
-
-\begin_inset  Tabular
+\begin_layout Standard
+\begin_inset Tabular
 <lyxtabular version="3" rows="7" columns="7">
 <features>
 <column alignment="center" valignment="top" leftline="true" width="0pt">
@@ -5527,503 +6337,571 @@
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Parameter
+\end_layout
 
-Parameter
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Update rate
+\end_layout
 
-Update rate
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+0
+\end_layout
 
-0
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+2
+\end_layout
 
-2
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+4
+\end_layout
 
-4
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Wideband bit
+\end_layout
 
-Wideband bit
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+1
+\end_layout
 
-1
-\end_inset 
+\end_inset
 </cell>
 </row>
 <row topline="true">
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+Mode ID
+\end_layout
 
-Mode ID
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+frame
+\end_layout
 
-frame
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
 \begin_inset Text
 
-\layout Standard
+\begin_layout Standard
+3
+\end_layout
 
-3
-\end_inset 
+\end_inset
 </cell>
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 </cell>
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-\end_inset 
+\end_inset
 </cell>
 </row>
 </lyxtabular>
 
-\end_inset 
+\end_inset
 
 
-\layout Caption
+\end_layout
 
+\begin_layout Caption
 Bit allocation for high-band in wideband mode
 \begin_inset LatexCommand \label{cap:bits-wideband}
 
-\end_inset 
+\end_inset
 
 
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Standard
 
+\end_layout
 
+\begin_layout Standard
 \begin_inset ERT
-status Open
+status open
 
-\layout Standard
+\begin_layout Standard
 
-\backslash 
+
+\backslash
 clearpage
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Standard
 
+\end_layout
 
+\begin_layout Standard
 \begin_inset ERT
-status Collapsed
+status collapsed
 
-\layout Standard
+\begin_layout Standard
 
-\backslash 
+
+\backslash
 clearpage
-\end_inset 
+\end_layout
 
+\end_inset
 
-\layout Section
-\start_of_appendix 
+
+\end_layout
+
+\begin_layout Section
+\start_of_appendix
 FAQ
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Vorbis is open-source
 \begin_inset LatexCommand \index{open-source}
 
-\end_inset 
+\end_inset
 
  and patent-free
 \begin_inset LatexCommand \index{patent}
 
-\end_inset 
+\end_inset
 
 ; why do we need Speex?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Vorbis is a great project but its goals are not the same as Speex.
  Vorbis is mostly aimed at compressing music and audio in general, while
  Speex targets speech only.
  For that reason Speex can achieve much better results than Vorbis on speech,
  typically 2-4 times higher compression at equal quality.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Isn't there an open-source implementation of the GSM-FR codec? Why is Speex
  necessary?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 First of all, it's not clear whether GSM-FR is covered by a Philips patent
  (see http://kbs.cs.tu-berlin.de/~jutta/toast.html).
  Also, GSM-FR offers mediocre quality at a relatively high bit-rate, while
  Speex can offer equivalent quality at almost half the bit-rate.
  Last but not least, Speex offers a wide range of bit-rates and sampling
  rates, while GSM-FR is limited to 8 kHz speech at 13 kbps.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Under what license is Speex released?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 As of version 1.0 beta 1, Speex is released under Xiph's version of the (revised)
  BSD license (see Appendix 
 \begin_inset LatexCommand \ref{sec:Speex-License}
 
-\end_inset 
+\end_inset
 
 ).
  This license is the most permissive of the open-source licenses.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Am I allowed to use Speex in commercial software?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Yes.
  As long as you comply with the license.
  This basically means you have to keep the copyright notice and you can't
@@ -6031,84 +6909,96 @@
  For more details, see license in Appendix 
 \begin_inset LatexCommand \ref{sec:Speex-License}
 
-\end_inset 
+\end_inset
 
 .
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Ogg
 \begin_inset LatexCommand \index{Ogg}
 
-\end_inset 
+\end_inset
 
 , Speex, Vorbis
 \begin_inset LatexCommand \index{Vorbis}
 
-\end_inset 
+\end_inset
 
 , what's the difference?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Ogg is a container format for holding multimedia data.
  Vorbis is an audio codec that uses Ogg to store its bit-streams as files,
  hence the name Ogg Vorbis.
  Speex also uses the Ogg format to store its bit-streams as files, so technicall
 y they would be 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 Ogg Speex
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
  files (I prefer to call them just Speex files).
  One difference with Vorbis however, is that Speex is less tied with Ogg.
  Actually, if you just do Voice over IP (VoIP), you don't need Ogg at all.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 What's the extension for Speex?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Speex files have the .spx extension.
  Note, however that the Speex tools (speexenc, speexdec) do not rely on
  the extension at all, so any extension will work.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Can I use Speex for compressing music
 \begin_inset LatexCommand \index{music}
 
-\end_inset 
+\end_inset
 
 ?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Just like Vorbis is not really adapted to speech, Speex is really not adapted
  for music.
  In most cases, you'll be better of with Vorbis when it comes to music.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 I converted some MP3s to Speex and the quality is bad.
  What's wrong?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This is called transcoding and it will always result in much poorer quality
  than the original MP3.
  Unless you have a really good (size) reason to do so, never transcode speech.
  This is even valid for self transcoding (tandeming), i.e.
  If you decode a Speex file and re-encode it again at the same bit-rate,
  you will lose quality.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Does Speex run on Windows?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Compilation on Windows has been supported since version 0.8.0.
  There are also several front-ends available from the website.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Why is encoding so slow compared to decoding?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 For most kinds of compression, encoding is inherently slower than decoding.
  In the case of Speex, encoding consists of finding, for each vector of
  5 to 10 samples, the entry that matches the best within a codebook consisting
@@ -6117,47 +7007,53 @@
  right entry in the codebook using the encoded index.
  Since a lookup is much faster than a search, the decoder works much faster
  than the encoder.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Why is Speex so slow on my iPaq (or insert any platform without an FPU)?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You probably didn't build Speex with the fixed-point option (--enable-fixed-poin
 t).
  Even if you did, not all modes have been ported to use fixed-point arithmetic,
  so the code may be slowed down by a few float operations left (e.g.
  in the wideband mode).
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 I'm getting unusual background noise (hiss) when using libspeex in my applicatio
 n.
  How do I fix that?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 One of the causes could be scaling of the input speech.
  Speex expects signals to have a 
 \begin_inset Formula $\pm2^{15}$
-\end_inset 
+\end_inset
 
  (signed short) dynamic range.
  If the dynamic range of your signals is too small (e.g.
  
 \begin_inset Formula $\pm1.0$
-\end_inset 
+\end_inset
 
 ), you will suffer important quantization noise.
  A good target is to have a dynamic range around 
 \begin_inset Formula $\pm8000$
-\end_inset 
+\end_inset
 
  which is large enough, but small enough to make sure there's no clipping
  when converting back to signed short.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 I get very distorted speech when using libspeex in my application.
  What's wrong?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 There are many possible causes for that.
  One of them is errors in the way the bits are manipulated.
  Another possible cause is the use of the same encoder or decoder state
@@ -6165,15 +7061,17 @@
  with the filter memories.
  If the input speech has an amplitude close to 
 \begin_inset Formula $\pm2^{15}$
-\end_inset 
+\end_inset
 
 , it is possible that at decoding, the amplitude be a bit higher than that,
  causing clipping when saving as 16-bit PCM.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 How does Speex compare to other proprietary codecs?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 It's hard to give precise figures since no formal listening tests have been
  performed yet.
  All I can say is that in terms of quality, Speex competes on the same ground
@@ -6186,80 +7084,88 @@
  ratio.
  Unlike many very expensive codecs, Speex is free and anyone may distribute
  or modify it at will.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Can Speex pass DTMF
 \begin_inset LatexCommand \index{DTMF}
 
-\end_inset 
+\end_inset
 
 ?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 I guess it all depends on the bit-rate used.
  Though no formal testing has yet been performed, I'd say is correctly at
  8 kbps and above (15 kbps for version < 1.1.1).
  Also, make sure you don't use the lowest complexity (see SPEEX_SET_COMPLEXITY
  or --comp option), as it causes significant noise.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 Can Speex pass V.9x modem signals correctly?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If I could do that I'd be very rich by now :-) Seriously, that would break
  fundamental laws of information theory.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 What is your (Jean-Marc) relationship with the University of Sherbrooke
  and how does Speex fit into that?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Currently (2005/05/11), I'm doing my 
-\emph on 
+\emph on
 Ph.D.
 
-\emph default 
+\emph default
  at the University of Sherbrooke in mobile robotics.
  Although I did my master with the Sherbrooke speech coding group (in speech
  enhancement, not coding), I am not associated with them anymore.
  It should 
-\series bold 
+\series bold
 not
-\series default 
+\series default
  be understood that they or the University of Sherbrooke have anything to
  do with the Speex project.
  Furthermore, Speex does not make use of any code or proprietary technology
  developed in the Sherbrooke speech coding group.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 CELP, ACELP
 \begin_inset LatexCommand \index{ACELP}
 
-\end_inset 
+\end_inset
 
 , what's the difference?
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 CELP stands for 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 Code Excited Linear Prediction
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
 , while ACELP stands for 
 \begin_inset Quotes eld
-\end_inset 
+\end_inset
 
 
-\emph on 
+\emph on
 Algebraic
-\emph default 
+\emph default
  Code Excited Linear Prediction
 \begin_inset Quotes erd
-\end_inset 
+\end_inset
 
 .
  That means ACELP is a CELP technique that uses an algebraic codebook represente
@@ -6267,107 +7173,138 @@
  This technique was invented at the University of Sherbrooke and is now
  one of the most widely used form of CELP.
  Unfortunately, since it is patented, it cannot be used in Speex.
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Sample code
 \begin_inset LatexCommand \label{sec:Sample-code}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This section shows sample code for encoding and decoding speech using the
  Speex API.
  The commands can be used to encode and decode a file by calling:
-\family typewriter 
+\family typewriter
 
-\newline 
+\newline
 % sampleenc in_file.sw | sampledec out_file.sw
-\family default 
+\family default
 
-\newline 
+\newline
 where both files are raw (no header) files encoded at 16 bits per sample
  (in the machine natural endianness).
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 sampleenc.c
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 sampleenc takes a raw 16 bits/sample file, encodes it and outputs a Speex
  stream to stdout.
  Note that the packing used is NOT compatible with that of speexenc/speexdec.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Include \verbatiminput{sampleenc.c}
 preview false
 
-\end_inset 
+\end_inset
 
 
-\layout Subsection
+\end_layout
 
+\begin_layout Subsection
 sampledec.c
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 sampledec reads a Speex stream from stdin, decodes it and outputs it to
  a raw 16 bits/sample file.
  Note that the packing used is NOT compatible with that of speexenc/speexdec.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Include \verbatiminput{sampledec.c}
 preview false
 
-\end_inset 
+\end_inset
 
 
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 IETF RTP Profile
 \begin_inset LatexCommand \label{sec:IETF-draft}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset Include \verbatiminput{draft-herlein-speex-rtp-profile-02.txt}
 preview false
 
-\end_inset 
+\end_inset
 
 
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 Speex License
 \begin_inset LatexCommand \label{sec:Speex-License}
 
-\end_inset 
+\end_inset
 
 
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Redistribution and use in source and binary forms, with or without modification,
  are permitted provided that the following conditions are met:
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 Neither the name of the Xiph.org Foundation nor the names of its contributors
  may be used to endorse or promote products derived from this software without
  specific prior written permission.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
  IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
@@ -6380,25 +7317,36 @@
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
-\layout Section
-\pagebreak_top 
+\end_layout
+
+\begin_layout Standard
+
+\newpage
+
+\end_layout
+
+\begin_layout Section
 GNU Free Documentation License
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Version 1.1, March 2000
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Copyright (C) 2000 Free Software Foundation, Inc.
  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted
  to copy and distribute verbatim copies of this license document, but changing
  it is not allowed.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 0.
  PREAMBLE
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The purpose of this License is to make a manual, textbook, or other written
  document "free" in the sense of freedom: to assure everyone the effective
  freedom to copy and redistribute it, with or without modifying it, either
@@ -6406,14 +7354,16 @@
  Secondarily, this License preserves for the author and publisher a way
  to get credit for their work, while not being considered responsible for
  modifications made by others.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This License is a kind of "copyleft", which means that derivative works
  of the document must themselves be free in the same sense.
  It complements the GNU General Public License, which is a copyleft license
  designed for free software.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 We have designed this License in order to use it for manuals for free software,
  because free software needs free documentation: a free program should come
  with manuals providing the same freedoms that the software does.
@@ -6423,24 +7373,28 @@
  We recommend this License principally for works whose purpose is instruction
  or reference.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 1.
  APPLICABILITY AND DEFINITIONS
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 This License applies to any manual or other work that contains a notice
  placed by the copyright holder saying it can be distributed under the terms
  of this License.
  The "Document", below, refers to any such manual or work.
  Any member of the public is a licensee, and is addressed as "you".
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 A "Modified Version" of the Document means any work containing the Document
  or a portion of it, either copied verbatim, or with modifications and/or
  translated into another language.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 A "Secondary Section" is a named appendix or a front-matter section of the
  Document that deals exclusively with the relationship of the publishers
  or authors of the Document to the Document's overall subject (or to related
@@ -6451,18 +7405,21 @@
  of historical connection with the subject or with related matters, or of
  legal, commercial, philosophical, ethical or political position regarding
  them.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The "Invariant Sections" are certain Secondary Sections whose titles are
  designated, as being those of Invariant Sections, in the notice that says
  that the Document is released under this License.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The "Cover Texts" are certain short passages of text that are listed, as
  Front-Cover Texts or Back-Cover Texts, in the notice that says that the
  Document is released under this License.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 A "Transparent" copy of the Document means a machine-readable copy, represented
  in a format whose specification is available to the general public, whose
  contents can be viewed and edited directly and straightforwardly with generic
@@ -6474,8 +7431,9 @@
  designed to thwart or discourage subsequent modification by readers is
  not Transparent.
  A copy that is not "Transparent" is called "Opaque".
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Examples of suitable formats for Transparent copies include plain ASCII
  without markup, Texinfo input format, LaTeX input format, SGML or XML using
  a publicly available DTD, and standard-conforming simple HTML designed
@@ -6484,20 +7442,23 @@
  read and edited only by proprietary word processors, SGML or XML for which
  the DTD and/or processing tools are not generally available, and the machine-ge
 nerated HTML produced by some word processors for output purposes only.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The "Title Page" means, for a printed book, the title page itself, plus
  such following pages as are needed to hold, legibly, the material this
  License requires to appear in the title page.
  For works in formats which do not have any title page as such, "Title Page"
  means the text near the most prominent appearance of the work's title,
  preceding the beginning of the body of the text.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 2.
  VERBATIM COPYING
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may copy and distribute the Document in any medium, either commercially
  or noncommercially, provided that this License, the copyright notices,
  and the license notice saying this License applies to the Document are
@@ -6508,16 +7469,19 @@
  However, you may accept compensation in exchange for copies.
  If you distribute a large enough number of copies you must also follow
  the conditions in section 3.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may also lend copies, under the same conditions stated above, and you
  may publicly display copies.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 3.
  COPYING IN QUANTITY
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If you publish printed copies of the Document numbering more than 100, and
  the Document's license notice requires Cover Texts, you must enclose the
  copies in covers that carry, clearly and legibly, all these Cover Texts:
@@ -6531,13 +7495,15 @@
  Copying with changes limited to the covers, as long as they preserve the
  title of the Document and satisfy these conditions, can be treated as verbatim
  copying in other respects.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If the required texts for either cover are too voluminous to fit legibly,
  you should put the first ones listed (as many as fit reasonably) on the
  actual cover, and continue the rest onto adjacent pages.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If you publish or distribute Opaque copies of the Document numbering more
  than 100, you must either include a machine-readable Transparent copy along
  with each Opaque copy, or state in or with each Opaque copy a publicly-accessib
@@ -6550,70 +7516,82 @@
  Transparent copy will remain thus accessible at the stated location until
  at least one year after the last time you distribute an Opaque copy (directly
  or through your agents or retailers) of that edition to the public.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 It is requested, but not required, that you contact the authors of the Document
  well before redistributing any large number of copies, to give them a chance
  to provide you with an updated version of the Document.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 4.
  MODIFICATIONS
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may copy and distribute a Modified Version of the Document under the
  conditions of sections 2 and 3 above, provided that you release the Modified
  Version under precisely this License, with the Modified Version filling
  the role of the Document, thus licensing distribution and modification
  of the Modified Version to whoever possesses a copy of it.
  In addition, you must do these things in the Modified Version: 
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 A.
  Use in the Title Page (and on the covers, if any) a title distinct from
  that of the Document, and from those of previous versions (which should,
  if there were any, be listed in the History section of the Document).
  You may use the same title as a previous version if the original publisher
  of that version gives permission.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 B.
  List on the Title Page, as authors, one or more persons or entities responsible
  for authorship of the modifications in the Modified Version, together with
  at least five of the principal authors of the Document (all of its principal
  authors, if it has less than five).
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 C.
  State on the Title page the name of the publisher of the Modified Version,
  as the publisher.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 D.
  Preserve all the copyright notices of the Document.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 E.
  Add an appropriate copyright notice for your modifications adjacent to
  the other copyright notices.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 F.
  Include, immediately after the copyright notices, a license notice giving
  the public permission to use the Modified Version under the terms of this
  License, in the form shown in the Addendum below.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 G.
  Preserve in that license notice the full lists of Invariant Sections and
  required Cover Texts given in the Document's license notice.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 H.
  Include an unaltered copy of this License.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 I.
  Preserve the section entitled "History", and its title, and add to it an
  item stating at least the title, year, new authors, and publisher of the
@@ -6622,8 +7600,9 @@
  the title, year, authors, and publisher of the Document as given on its
  Title Page, then add an item describing the Modified Version as stated
  in the previous sentence.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 J.
  Preserve the network location, if any, given in the Document for public
  access to a Transparent copy of the Document, and likewise the network
@@ -6632,32 +7611,37 @@
  You may omit a network location for a work that was published at least
  four years before the Document itself, or if the original publisher of
  the version it refers to gives permission.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 K.
  In any section entitled "Acknowledgements" or "Dedications", preserve the
  section's title, and preserve in the section all the substance and tone
  of each of the contributor acknowledgements and/or dedications given therein.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 L.
  Preserve all the Invariant Sections of the Document, unaltered in their
  text and in their titles.
  Section numbers or the equivalent are not considered part of the section
  titles.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 M.
  Delete any section entitled "Endorsements".
  Such a section may not be included in the Modified Version.
-\layout Itemize
+\end_layout
 
+\begin_layout Itemize
 N.
  Do not retitle any existing section as "Endorsements" or to conflict in
  title with any Invariant Section.
  
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If the Modified Version includes new front-matter sections or appendices
  that qualify as Secondary Sections and contain no material copied from
  the Document, you may at your option designate some or all of these sections
@@ -6665,14 +7649,16 @@
  To do this, add their titles to the list of Invariant Sections in the Modified
  Version's license notice.
  These titles must be distinct from any other section titles.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may add a section entitled "Endorsements", provided it contains nothing
  but endorsements of your Modified Version by various parties--for example,
  statements of peer review or that the text has been approved by an organization
  as the authoritative definition of a standard.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may add a passage of up to five words as a Front-Cover Text, and a passage
  of up to 25 words as a Back-Cover Text, to the end of the list of Cover
  Texts in the Modified Version.
@@ -6682,25 +7668,29 @@
  added by you or by arrangement made by the same entity you are acting on
  behalf of, you may not add another; but you may replace the old one, on
  explicit permission from the previous publisher that added the old one.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The author(s) and publisher(s) of the Document do not by this License give
  permission to use their names for publicity for or to assert or imply endorseme
 nt of any Modified Version.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 5.
  COMBINING DOCUMENTS
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may combine the Document with other documents released under this License,
  under the terms defined in section 4 above for modified versions, provided
  that you include in the combination all of the Invariant Sections of all
  of the original documents, unmodified, and list them all as Invariant Sections
  of your combined work in its license notice.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The combined work need only contain one copy of this License, and multiple
  identical Invariant Sections may be replaced with a single copy.
  If there are multiple Invariant Sections with the same name but different
@@ -6709,37 +7699,43 @@
  that section if known, or else a unique number.
  Make the same adjustment to the section titles in the list of Invariant
  Sections in the license notice of the combined work.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 In the combination, you must combine any sections entitled "History" in
  the various original documents, forming one section entitled "History";
  likewise combine any sections entitled "Acknowledgements", and any sections
  entitled "Dedications".
  You must delete all sections entitled "Endorsements."
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 6.
  COLLECTIONS OF DOCUMENTS
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may make a collection consisting of the Document and other documents
  released under this License, and replace the individual copies of this
  License in the various documents with a single copy that is included in
  the collection, provided that you follow the rules of this License for
  verbatim copying of each of the documents in all other respects.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may extract a single document from such a collection, and distribute
  it individually under this License, provided you insert a copy of this
  License into the extracted document, and follow this License in all other
  respects regarding verbatim copying of that document.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 7.
  AGGREGATION WITH INDEPENDENT WORKS
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 A compilation of the Document or its derivatives with other separate and
  independent documents or works, in or on a volume of a storage or distribution
  medium, does not as a whole count as a Modified Version of the Document,
@@ -6748,19 +7744,22 @@
  apply to the other self-contained works thus compiled with the Document,
  on account of their being thus compiled, if they are not themselves derivative
  works of the Document.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 If the Cover Text requirement of section 3 is applicable to these copies
  of the Document, then if the Document is less than one quarter of the entire
  aggregate, the Document's Cover Texts may be placed on covers that surround
  only the Document within the aggregate.
  Otherwise they must appear on covers around the whole aggregate.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 8.
  TRANSLATION
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Translation is considered a kind of modification, so you may distribute
  translations of the Document under the terms of section 4.
  Replacing Invariant Sections with translations requires special permission
@@ -6771,12 +7770,14 @@
  the original English version of this License.
  In case of a disagreement between the translation and the original English
  version of this License, the original English version will prevail.
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 9.
  TERMINATION
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 You may not copy, modify, sublicense, or distribute the Document except
  as expressly provided for under this License.
  Any other attempt to copy, modify, sublicense or distribute the Document
@@ -6785,19 +7786,22 @@
  License will not have their licenses terminated so long as such parties
  remain in full compliance.
  
-\layout Subsection*
+\end_layout
 
+\begin_layout Subsection*
 10.
  FUTURE REVISIONS OF THIS LICENSE
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 The Free Software Foundation may publish new, revised versions of the GNU
  Free Documentation License from time to time.
  Such new versions will be similar in spirit to the present version, but
  may differ in detail to address new problems or concerns.
  See http://www.gnu.org/copyleft/.
-\layout Standard
+\end_layout
 
+\begin_layout Standard
 Each version of the License is given a distinguishing version number.
  If the Document specifies that a particular numbered version of this License
  "or any later version" applies to it, you have the option of following
@@ -6807,12 +7811,15 @@
  If the Document does not specify a version number of this License, you
  may choose any version ever published (not as a draft) by the Free Software
  Foundation.
-\layout Standard
+\end_layout
 
-
+\begin_layout Standard
 \begin_inset LatexCommand \printindex{}
 
-\end_inset 
+\end_inset
 
 
-\the_end
+\end_layout
+
+\end_body
+\end_document