The Problem

I have a mkv file that contains audio in a format that not all my devices support. To get full support, I want to copy that audio and convert it while retaining the original audio.


  • mkv
  • 4 stereo audio tracks


  • mka (I only care about the audio)
  • 2 stereo audio tracks (original, track 0 and 2 copied)
  • 2 stereo audio tracks (converted, track 0 -> track 1, track 2 -> track 3)
  • the original track 1 and 3 shall be discarded

What I´ve found so far (using ffmpeg 6.1):

To copy audio track 0 and 2, I can use the following command:

ffmpeg -i input.mkv -map 0:a -c:a:0 copy -c:a:2 copy output.mka

And this command to change the audio format of track 0 to OPUS.

ffmpeg -i intput.mkv -map 0:a -mapping_family 1 -ac 6 -c:a:0 libopus -metadata:s:a:0 title='Opus 5.1' -metadata:s:a:0 language='eng' output.mka

I think I can remove the -mapping_family 1 -ac 6 part, as I´m only dealing with stereo audio.

The question:

How can I combine both commands to get the following track layout?:

  • track 0 (original, copied, metadata retained)
  • track 1 (re-encode from track 0)
  • track 2 (original, copied, metadata retained)
  • track 3 (re-encode from track 2)
  • 1
    mapping ffmpeg -i "$f" -map 0:a:0 -map 0:a:0 -map 0:a:2 -map 0:a:2 -c:0 copy -c:1 libopus -c:2 copy -c:3 libopus -metadata:s:0 title="aac 0" -metadata:s:1 title="Opus 1" -metadata:s:2 title="aac 2" -metadata:s:3 title="Opus 3" /tmp/out.mka Mar 18 at 2:09


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