[FFmpeg-devel] [PATCH] lavc: export flag for MPEG audio dual channel

[Andreas Rheinhardt]

Rémi Denis-Courmont:
> Le keskiviikkona 21. syyskuuta 2022, 22.26.11 EEST Scott Theisen a écrit :
>> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
>> index 7db5d1b1c5..bcf3a845a8 100644
>> --- a/libavcodec/avcodec.h
>> +++ b/libavcodec/avcodec.h
>> @@ -2076,6 +2076,17 @@ typedef struct AVCodecContext {
>>       *             The decoder can then override during decoding as needed.
>> */
>>      AVChannelLayout ch_layout;
>> +
>> +    /**
>> +     * Audio only.  This flag is set when MPEG audio mode dual channel has
>> been detected. +     * This signals that the audio is two independent mono
>> channels. +     *
>> +     * 0 normally, 1 if dual channel flag is set.
>> +     *
>> +     * - encoding: currently unused (functionally equivalent to stereo,
>> patch welcome) +     * - decoding: set by lavc
>> +     */
>> +    int mpeg_audio_mode_dual_channel;
>>  } AVCodecContext;
> 
> I agree that the dual mono flag should be exposed to the application somehow, 
> but isn't this a slient ABI break?
> 

Now. sizeof(AVCodecContext) is not part of the public ABI (we have a
custom allocator for it: avcodec_alloc_context3()).

- Andreas