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

Vladimir Voroshilov voroshil
Wed Jun 10 03:37:00 CEST 2009

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

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

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

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