I'm trying to copy video/audio from an mkv container to mp4. When I run
ffmpeg -i input.mkv -c:v copy -c:a copy output.mp4 I'm given no video with polish audio. There's only one video stream, stream #0:0. Stream #0:1 is polish audio, #0:2 english, and #0:3 – #0:5 are subtitles.
I read this https://trac.ffmpeg.org/wiki/How%20to%20use%20-map%20option but don't understand it really. Why is -map 0:1 written twice in example 1? What does -c:s do? What would a command to copy #0:0 to video and #0:2 to audio look like?