[FFmpeg-devel] [PATCH 2/2] avformat/riffdec: follow the MS docs more strictly for setting wav channel layouts

[Marton Balint]

On Tue, 19 Mar 2024, Michael Niedermayer wrote:

> On Sun, Mar 17, 2024 at 08:57:29PM +0100, Marton Balint wrote:
>> - Only parse the defined masks in dwChannelMask, unless strict_std_compliance
>>   is less than normal. This matches with the behaviour of the wav muxer.
>> - Ignore additional bits in dwChannelMasks as the MS documentation suggests [1]
>> - Assume UNKNOWN channels for missing bits as the MS documentation suggests [1]
>>
>> [1] https://learn.microsoft.com/en-us/previous-versions/windows/hardware/design/dn653308(v=vs.85)#details-about-dwchannelmask
>>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  libavformat/riffdec.c | 28 +++++++++++++++++++++++++---
>>  1 file changed, 25 insertions(+), 3 deletions(-)
>
> breaks:
> ./ffmpeg  -i ~/tickets/2859/5.1plusdownmix.wav -ac 2 -t 100 -bitexact -c:a aac -y /tmp/2859-frenchspeack-nolibfaac.mp4

After the patch this is file will need -strict unofficial to work, since 
the downmix channels are not officially recognized in the dwChannelMask.

Regards,
Marton