Opened 14 years ago
Closed 14 years ago
#6 closed defect (fixed)
Alsa output channel order is wrong
| Reported by: | Carl Eugen Hoyos | Owned by: | Michael Niedermayer |
|---|---|---|---|
| Priority: | normal | Component: | avformat |
| Version: | git | Keywords: | |
| Cc: | Blocked By: | ||
| Blocking: | Reproduced by developer: | yes | |
| Analyzed by developer: | yes |
Description
http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/129213
When using ffmpeg -i input -f alsa, the channel order is typically wrong for >2 channels.
Alsa expects 5.1 in the order: front left - front right - surround left - surround right - centre - lfe, FFmpeg's internal channel order is front left - front right - centre - lfe - surround left - surround right (for 7.1, back channels are last in both cases).
The order is correct for AV_CH_LAYOUT_QUAD, for AV_CH_LAYOUT_4POINT0 (Edward.Scissorhands.x264.DTS-4.0-48_24.mkv), it would be necessary to expand output to (at least) five channels.
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This is fixed now for 5.1 and 7.1 audio.
I believe it would make sense for four and five channel audio to automatically select six channel alsa output and map the channels accordingly. This has not been implemented yet.