Subject: Re: G723

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 26 Apr 2000 10:28:58 -0400

Art Yerkes wrote:
> 
> For G.723, http://www.cwi.nl/ftp/audio/ccitt-adpcm.tar.gz.  These
> sources come from sun.  Not sure if they're any faster, though.

Thanks for all the responses. A brief summary:

- The ITU floating point code for G.729 is significantly faster than the
fixed-point code. Decoding takes about 8% of a SPARC Ultra CPU, encoding
about a third.

- The term G.723 is the subject of endless confusion. The source cited
above is the "old" G.723. The RTP profile explains it thusly:

"Note: In 1990, ITU-T Recommendation G.721 was merged with
Recommendation
G.723 into ITU-T Recommendation G.726. Thus, G726-32 designates the same
algorithm as G721 in RFC 1890."

Most people (myself included) seem to use the term G.723 now for what's
more precisely called G.723.1, the 5.3/6.3 kb/s codec.

Thanks again.
-- 
Henning Schulzrinne   http://www.cs.columbia.edu/~hgs

---

From: Simao Campos <[email-masked]>
Date: Wed, 26 Apr 2000 11:02:20 -0400

Art,

Yes, G.723 is a "vacant" recommendation number now. For a short period
of time, experts referred to the 6.3/5.3 kb/s ACELP/MP-LPC ITU codec
as G.723, but this was quickly changed to G.723.1, to avoid confusion
with the 24, 40 kb/s ADPCM G.723 spec. So any "modern" reference to
G.723 has been to actually designate G.723.1. Do you feel we need more
clear text on that regard in RTP profile?

BTW, the code from Sun in ccitt-adpcm.tar.gz does not process the ITU
test vectors correctly, hence it cannot be claimed to comply to the
ITU Standard (Note for newbies: the ITU-T was formerly known as
CCITT). The code in the ITU Software Tool Library does, and runs very
fast on today's CPUs.

Simao.

>>>>> "Henning" == Henning Schulzrinne <[email-masked]> writes:

    >> sources come from sun.  Not sure if they're any faster, though.

    Henning> Thanks for all the responses. A brief summary:

    Henning> - The ITU floating point code for G.729 is significantly faster than the
    Henning> fixed-point code. Decoding takes about 8% of a SPARC Ultra CPU, encoding
    Henning> about a third.

    Henning> - The term G.723 is the subject of endless confusion. The source cited
    Henning> above is the "old" G.723. The RTP profile explains it thusly:

    Henning> "Note: In 1990, ITU-T Recommendation G.721 was merged with
    Henning> Recommendation
    Henning> G.723 into ITU-T Recommendation G.726. Thus, G726-32 designates the same
    Henning> algorithm as G721 in RFC 1890."

    Henning> Most people (myself included) seem to use the term G.723 now for what's
    Henning> more precisely called G.723.1, the 5.3/6.3 kb/s codec.

    Henning> Thanks again.
    Henning> -- 
    Henning> Henning Schulzrinne   http://www.cs.columbia.edu/~hgs