MKV merge audio

Extract audio from MP4 movie file

ffmpeg -i input_dubbing_PL.mp4 -vn --codec copy pl_audio.aac

Note: -vn option means no video. Only audio is being extracted.

Add second audio track to existing MKV file

The following command will create the file output.mkv with two audio tracks:

• pl - the track to be added
• en - original audio track existing in input.mkv movie file.

mkvmerge -o output.mkv --language 0:pl pl_audio.aac --language 1:en input.mkv