[FFmpeg-devel] [PATCH] Common ACELP code & G.729 [4/7] - G.729 core

Vladimir Voroshilov voroshil
Thu Aug 21 18:18:30 CEST 2008

2008/8/20 Michael Niedermayer <michaelni at gmx.at>:
> On Sat, Aug 16, 2008 at 06:34:59PM +0700, Vladimir Voroshilov wrote:


>> VOC format (based on G.729 AnnexD) uses slightly different packet coding.
>> But it can be handled by my g729d code after replacing only this one routine.
>> With inlined readings it will be harder to implement, imho.
> elaborate on what is exactly different

0. bits in each byte follows in reverse order.
1. Parity bit is eliminated
2. second adaptive-codebook index for both subframes  has only 2 bits
instead of 3 (LSB assumed equal to 0).
3. index of first fixed-codebook  pulse for both subframes has only 2
bits instead of 4 (2 LSBs assumed equal to 0)
4. index of second fixed-codebook pulse for both subframes has 3 bits
instead of 4 (LSB assumed equal to 1)

The rest are the same.

Conversion can be done as in decoder as in demuxer.
In the latter case parameters can be read in-place without separate
routine (exactly as you suggest).
If this is preferred tell me and i'll remove separate routine.

P.S. VOC also uses different gain codebooks and fixed-vector pulses
coding. So my words about "only one routine" were wrong.

Vladimir Voroshilov mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719

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