On 19/03/2024 20:14, Marton Balint wrote:
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 <c...@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.
I think downmix channels are part of the RF64 specification, see EBU
Tech 3306 section 3.1:
"""
3.1 Enhancement for a PCM stereo down mix
No PCM stereo signal is included in the basic Wave Format Extensible.
To include a stereo channel the following is added:
#define SPEAKER_STEREO_LEFT 0x20000000
#define SPEAKER_STEREO_RIGHT 0x40000000
"""
Regards, Tobias
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