[FFmpeg-devel] [PATCH] G.729 initialization routine (skeleton)

[Vladimir Voroshilov]

2009/6/10 Pavel Pavlov <pavel at summit-tech.ca>:
>> -----Original Message-----
>> > > On Wed, Jun 10, 2009 at 12:27:35AM +0700, Vladimir
>> Voroshilov wrote:
>> > Well...
>> > First look give me (at least for 8k and 6k4. i'll finally
>> drop out 4k4
>> > in next patch since i've no method to test it):
>> > avctx->sample_rate=8000
>> > avctx->bit_rate = 8000 and 6400 respectively frame_size =
>> > avctx->avctx->sample_rate /100 (1 packet = 10ms)
> ...
>> >> G.729 standard also describes 11.5k and 6.4k modes (and also
>> >> several non-standard modes exists, like above 4.4k).
>> >> So what will be happend if such mode will be passed to decoder ?
>> >
>> > as the values you quote are bitrates and the check is testing the
>> > samplerate ...
>
> I'm a bit surprised about 4k4. Also, it's not 11.5, but 11.8. Where did

You right, sorry. 11.8 or course.

> you find that there is 4k4 in g729 and how could there be non standard
> bitrates?

In chinese cheap mp3 players.

> As far as I know, 8k is the main bitrate, and there were g729 annex e
> and f that are 6.4 and 11.8kbit. Annex b has vad, so maybe when vad is
> used and DTX is disabled it could be anything else other than 6.4/8/11.8

4k4 is pure non-standard (not described anywhere) since it is hacked 8k version,
used in some cheap mp3 players (called "Long-voice" mode recording there).

This as all thing, known about this mode
http://wiki.multimedia.cx/index.php?title=ACT

There were already suggestions (long time ago) to remove it from decoder,
till at least one sample file will be available.


-- 
Regards,
Vladimir Voroshilov     mailto:voroshil at gmail.com
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