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

[Vladimir Voroshilov]

2009/6/10 Michael Niedermayer <michaelni at gmx.at>:
> On Wed, Jun 10, 2009 at 12:27:35AM +0700, Vladimir Voroshilov wrote:
>> 2009/6/10 Michael Niedermayer <michaelni at gmx.at>:
>> > On Tue, Jun 09, 2009 at 11:30:17PM +0700, Vladimir Voroshilov wrote:
>> >> 2009/6/9 Michael Niedermayer <michaelni at gmx.at>:
>> >> > On Sun, Jun 07, 2009 at 12:28:37AM +0700, Vladimir Voroshilov wrote:
>> >> >> 2009/6/7 Diego Biurrun <diego at biurrun.de>:
>> >> >> > On Sun, Jun 07, 2009 at 12:18:10AM +0700, Vladimir Voroshilov wrote:
>> >> >> >>
>> >> >> >> Here is patch without format.
>> >> >> >>
>> >> >> >> --- ffmpeg-r19125.orig/libavcodec/g729dec.c
>> >> >> >> +++ ffmpeg-r19125.mod/libavcodec/g729dec.c
>> >> >> >> @@ -97,11 +101,39 @@ static inline int get_parity(uint8_t value)
>> >> >> >>
>> >> >> >> +static int decoder_init(AVCodecContext * avctx)
>> >> >> >
>> >> >> > This function should likely be marked av_cold.
>> >> >> >
>> >> >> > Please doublecheck which other functions could receive this attribute.
>> >> >> >
>> >> >>
>> >> >> decoder_init does not call other internal routines, thus no additional
>> >> >> routines require this attribute, imho.
>> >> >> fixed.
>> >> > [...]
>> >> >
>> >> >> + ? ?if (avctx->sample_rate == 8000) {
>> >> >> + ? ? ? ?ctx->subframe_size = 40;
>> >> >> +#ifdef G729_SUPPORT_4400
>> >> >> + ? ?} else if (avctx->sample_rate == 4400) {
>> >> >> + ? ? ? ?ctx->subframe_size = 44;
>> >> >> +#endif
>> >> >> + ? ?} else {
>> >> >> + ? ? ? ?av_log(avctx, AV_LOG_ERROR, "Sample rate %d is not supported.\n", avctx->sample_rate);
>> >> >> + ? ? ? ?return AVERROR_NOFMT;
>> >> >> + ? ?}
>> >> >
>> >> > ? ?ctx->subframe_size = 40;
>> >> > #ifdef G729_SUPPORT_4400
>> >> > ? ?if (avctx->sample_rate == 4400) {
>> >> > ? ? ? ?ctx->subframe_size = 44;
>> >> > ? ?}
>> >> > #endif
>> >>
>> >> In this casse you'll get garbage sound instead of meanfull error
>> >> message for unsupported g.729 modes.
>> >
>> > which mode?
>>
>> 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 ...
>

OMG! I've mixed bit_rate and sample_rate.

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
avctx->frame_size = avctx->sample_rate /100 (1 packet = 10ms)

ctx->subframe_size=avctx->frame_size/2
ctx->packed_frame_size = avctx-bit_rate / 800 (1 packet = 10ms and bits->bytes)
ctx->unpacked_frame_size = avctx->frame_size * sizeof(int16_t)

No format tables at this stage are required (they will due to
different bits allocation in packet)!
I'll test and fix all these calculations in next patch, but i have
several question now:

1. Who should initialize sample_rate and frame_size (decoder or demuxer) ?
2. Can i be sure that output buffer passed to decode_frame will be at
least frame_size*2 long or i have to check this explicitly ?

3. What should i pass instead of X, Y and Z to av_set_pts(st, X, Y, Z)
in demuxer to ensure that all packets will be
packets_frame_size long (10 and 8 bytes respectively) ? av_set_pts(st,
10, bit_rate, sample_rate) if all packets are 10ms ?
Perhaps i should set up packet size in different way ?

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