FFMpeg - convert all audio streams from MKV to MP4

1
votes

I have MKV file which contains:

Stream #0:0(eng): Video: h264 (High)
Stream #0:1(pol): Audio: ac3
Stream #0:2(eng): Audio: dts (DTS)
Stream #0:3(pol): Subtitle: subrip
Stream #0:4(eng): Subtitle:  hdmv_pgs_subtitle

I would like to omit subtitles (-sn option), copy video and encode audio streams to AAC.

I tried few various command and output file is always the same (2 audio streams but in both sound from first audio stream).

Here are my commands:

ffmpeg -i input.mkv -sn -map 0:a? -map 0:v -c:v copy -c:a? aac output.mp4 
ffmpeg -i input.mkv -sn -map 0 -c:v copy -c:a aac output.mp4 
ffmpeg -i input.mkv -sn -map 0:? -c:v copy -c:a aac output.mp4

Everything almost work but in output file I have 2 audio streams with name (pol) and (eng) but in both is sound from (pol) stream0:1.

What command should I use to convert audio streams in order to achieve two a audio streams where will be pol and eng sound (not pol in both of them). Sometimes input file has only 1 audio stream so to command line should be universal, I guess ffmpeg map with ? character.

1
ffmpeg

1 Answers

4
votes

If the streams in the MKV file are compatible with MP4

You can remux with stream copy mode (-c copy). This avoids re-encoding.

ffmpeg -i input.mkv -map 0 -c copy output.mp4

  • -map 0 selects all streams from input #0 which is input.mkv (note that ffmpeg starts counting from 0). Otherwise the default stream selection behavior is used which will only select one stream per stream type.

  • ffmpeg will tell you if a stream is not compatible with the output container format with an error message: codec not currently supported in container.

  • Currently the most typical compatible formats are: H.264 video, H.265/HEVC video, and AAC audio.

Excluding incompatible streams

You can use negative mapping. Example to include everything except subtitles:

ffmpeg -i input.mkv -map 0 -map -0:s -c copy output.mp4

See the -map option documentation for more info.

Re-encoding incompatible streams

This example stream copies everything except for audio which is converted to AAC:

ffmpeg -i input.mkv -map 0 -c copy -c:a aac output.mp4