[xiph-cvs] r6714 - trunk/theora/doc/spec

[tterribe at xiph.org]

Author: tterribe
Date: 2004-05-17 22:49:48 -0400 (Mon, 17 May 2004)
New Revision: 6714

Modified:
   trunk/theora/doc/spec/spec.tex
Log:
Continued macro block modes section.

<p>Modified: trunk/theora/doc/spec/spec.tex
===================================================================
--- trunk/theora/doc/spec/spec.tex	2004-05-17 19:39:35 UTC (rev 6713)
+++ trunk/theora/doc/spec/spec.tex	2004-05-18 02:49:48 UTC (rev 6714)
@@ -30,6 +30,7 @@
 \newcommand{\sbi}{\idx{sbi}}
 \newcommand{\bi}{\idx{bi}}
 \newcommand{\mbi}{\idx{mbi}}
+\newcommand{\mi}{\idx{mi}}
 \newcommand{\ti}{\idx{ti}}
 %This somewhat odd construct ensures that \bitvar{\qi}, etc., will set the
 % qi in bold face, even though it is in a \mathit font, yet \bitvar{VAR} will
@@ -363,6 +364,7 @@
  the various processing steps.
 
 \subsubsection{Macro Blocks}
+\label{sec:mbs}
 
 A macro block contains a $2\times 2$ array of blocks in the luma plane
  {\em and} the co-located blocks in the chroma planes.
@@ -3463,10 +3465,60 @@
 \label{tab:mode-codes}
 \end{table}
 
+\begin{enumerate}
+\item
+If \bitvar{FTYPE} is 0 (intra frame):
+\begin{enumerate}
+\item
+For each consecutive value of \locvar{\mbi} from 0 to $(\bitvar{NMBS}-1)$,
+ inclusive, assign $\bitvar{MBMODES}[\mbi]$ the value 0 (INTRA).
+\end{enumerate}
+\item
+Otherwise (inter frame):
+\begin{enumerate}
+\item
+Read a 3-bit unsigned integer as \locvar{MSCHEME}.
+\item
+If \locvar{MSCHEME} is 0:
+\begin{enumerate}
+\item
+For each consecutive value of \locvar{MODE} from 0 to 7, inclusive:
+\begin{enumerate}
+\item
+Read a 3-bit unsigned integer as \locvar{\mi}.
+\item
+Assign $\locvar{MALPHABET}[\mi]$ the value \locvar{MODE}.
+\end{enumerate}
+\end{enumerate}
+\item
+Otherwise, if \locvar{MSCHEME} is not 7, assign the entries of
+ \locvar{MALPHABET} the values in the corresponding column of
+ Table~\ref{tab:mode-codes}.
+\item
+For each consecutive macro block in coded order (see
+ Section~\ref{sec:mbs})---indexed by \locvar{\mbi}:
+\begin{enumerate}
+\item
+If a block \locvar{\bi} in the luma plane of macro block \locvar{\mbi} exists
+ such that $\bitvar{BCODED}[\locvar{\bi}]$ is 1:
+\begin{enumerate}
+\item
+If \locvar{MSCHEME} is not 7, read one bit at a time until one of the Huffman
+ codes in Table~\ref{tab:mode-codes} is recognized, and assign
+ $\bitvar{MBMODE}[\locvar{\mbi}]$ the value $\locvar{MALPHABET}[\locvar{\mi}]$,
+ where \locvar{\mi} is the index of the Huffman code decoded.
+\item
+Otherwise, if no luma-plane blocks in the macro block are coded, read a 3-bit
+ unsigned integer as $\bitvar{MBMODE}[\locvar{\mbi}]$.
+\end{enumerate}
+\item
+Otherwise, assign $\bitvar{MBMODE}[\locvar{\mbi}]$ the value 0 (INTER\_NOMV).
+\end{enumerate}
+\end{enumerate}
+\end{enumerate}
 
 
 
-
 \appendix
 
 \clearpage

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'cvs-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.