[vorbis-dev] Re: Speex: Open-source, patent-free speech coding

[DSPguru]

Greetings developers, Jean-Marc,

Great to hear about your work. i find speech encoding pretty useful.

these days we think about MultiLingual vorbis defenitions, and the best
compression we could acheive were if we could save the common track on
two channels, and then save the delta between the common track to the
specifiec language (english speech/italian speech/etc'..) on a low
bandwidth track. a vocoder track for this task could be very
interesting. don't you think ?

another point,
I wanted to ask why you had decided to develop CELP, which is based on
linear prediction (LPC), while there are multi-band excitation (MBE)  
speech coders (IMBE/AMBE) that have better compression-gain (down to 2kbps),
and consumes less MIPS. i heard some samples of DVSI's vocoders, and i 
must admit that their quality is very very good.
LPC is abit old, isn't it ?-)

<p>Good luck with your work !
Dg. http://DSPguru.doom9.net

<p>Jean-Marc Valin wrote:
> 
> Hi,
> 
> We would like to announce the first release of the Speex project. Speex
> (http://speex.sourceforge.net) is an open-source (LGPL), patent-free
> compression format allowing an alternative to expensive proprietary
> codecs. Unlike Ogg Vorbis which compresses general audio, Speex is
> designed especially for speech. For that reason, Speex is meant to be a
> complement to Vorbis. Since it is specialized for voice communications,
> it is possible to attain lower (compared to Ogg Vorbis/MP3) bit-rates in
> the 8-32 kbps/channel range. Possible applications include Voice over IP
> (VoIP) applications, Internet audio streaming at low bit-rate and
> archiving of speech data (e.g. voice mail).
> 
> This first version of Speex supports fixed bit-rate CELP coding at 14.5
> kbps for speech sampled at 8 kHz (narrowband) and at 28.5 kbps for 16
> kHz (wideband) speech. Future releases will likely provide a wider
> choice of bit-rates, better quality, as well as variable bit-rate (VBR)
> and discontinuous transmission (DTX).
> 
> Disclaimer:
> 
> Note that this is a preliminary release and that bit-rates, quality and
> bitstream definition will change in the future. This means that the
> format used in this release will not be compatible with future releases.
> Also note that this software has so far received only a minimum amount
> of testing, so it may break or do unexpected things.
> 
> --
> Jean-Marc Valin, M.Sc.A.
> LABORIUS (http://www.gel.usherb.ca/laborius)
> Université de Sherbrooke, Québec, Canada

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