[FFmpeg-user] more sound madness, looks SOLVED

Ted Park kumowoon1025 at gmail.com
Thu Mar 12 03:37:09 EET 2020


Glad you were able to figure out how to filter/remap to get the desired effect.
> ...
> Probably, but that’s beside the issue, it’s not up to me what end users want to map to where :-)
Oh right! I thought this was a personal project for some reason, that you were the one making the recording/mixing  😐

> What DOES work as expected:
> (Reverse mapping of BWF sound, with the last channel duplicated, reverse mapping of the two video sound channels.)
> The channelmap from the BWF is a sum of (zero based) 2 to 12 from you list above, to leave room for the 0x3 (first two) for the video sound:
> /Applications/ffmpeg -i /Volumes/Data/test/10track.wav -i /Volumes/Data/test/input.mp4 -filter_complex "[0:a]channelmap=9-0|8-1|7-2|6-3|5-4|4-5|3-6|2-7|1-8|0-9|9-10:channel_layout=0x8FFC,[1:a]join=inputs=2:channel_layout=0x1FFF,channelmap=map=0-0|1-1|2-2|3-3|4-4|5-5|6-6|7-7|8-8|9-9|10-10|11-11|12-12:channel_layout=0x1FFF[out]" -map "[out]" -c:a pcm_s24le -map 1:1 -c:v copy  /Volumes/Data/test/ted59.mov
> To make it easier, amerge, works as expected:
> /Applications/ffmpeg -i /Volumes/Data/test/10track.wav -i /Volumes/Data/test/input.mp4 -filter_complex "[0:a]channelmap=9-0|8-1|7-2|6-3|5-4|4-5|3-6|2-7|1-8|0-9|9-10:channel_layout=0x8FFC[a0];[1:a]channelmap=1-0|0-1:channel_layout=0xC[a1];[a1][a0]amerge=inputs=2[out]" -map "[out]" -c:a pcm_s24le -map 1:1 -c:v copy /Volumes/Data/test/ted61.mov
> Even easier: (Since the filter_complex now isn’t feeding the next, and proof that the channelmap is just a dummy:
> /Applications/ffmpeg -i /Volumes/Data/test/10track.wav -i /Volumes/Data/test/input.mp4 -filter_complex "[0:a]channelmap=9-0|8-1|7-2|6-3|5-4|4-5|3-6|2-7|1-8|0-9|9-10:channel_layout=0x7FF[a0];[1:a]channelmap=1-0|0-1:channel_layout=0x3[a1];[a1][a0]amerge=inputs=2[out]" -map "[out]" -c:a pcm_s24le -map 1:1 -c:v copy /Volumes/Data/test/ted62.mov
> This makes it easy to break the whole shebang down so an end user can map any combo in any order without me having to jump hoops :-)

Thanks for breaking it down.

Still think there needs to be an easier way to perform channel manipulation, but I don’t have any ideas either...

Ted Park

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