[FFmpeg-user] Concat filter with more than 1 audio stream -- How?

[Moritz Barsnick]

On Sun, Feb 23, 2020 at 20:06:41 -0500, Mark Filipak wrote:
> Using this:
>
> ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex
> '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
> concat=n=3:v=1:a=2 [v] [a1] [a2]' -map '[v]' -map '[a1]' -map '[a2]'
> output.mkv

Note the leading 0, 1, 2 to denote ffmpeg's three inputs.

> as a template, I wrote this:
>
> ffmpeg -i i:\VIDEO_TS\VTS_02_1.VOB -i i:\VIDEO_TS\VTS_02_2.VOB -i
> i:\VIDEO_TS\VTS_02_3.VOB -i i:\VIDEO_TS\VTS_02_4.VOB -i
> i:\VIDEO_TS\VTS_02_5.VOB -filter_complex '[0:1] [0:2] [0:3] [0:4] [0:5]
> concat=n=5:v=1:a=4 [v] [a1] [a2] [a3] [a4]' -map '[v]' -map '[a1]' -map
> '[a2]' -map '[a3]' -map '[a4]' n:\output.mkv

Note that you are using only leading '0's, so only the first input file
will be used.

> [AVFilterGraph @ 0000016ac31b6cc0] No such filter: '[0:1]'

I have no idea where that would come from. Could you use "-loglevel
debug" to show how ffmpeg evaluates the command line?

Thanks,
Moritz