Kissaki, rok temu

With ffmpeg

<span style="color:#323232;">ffmpeg -i src -c copy -map 0:v:0 -map 0:v:1 -map 0:a out.mkv
</span>

ffmpeg uses a sectioned parameter approach. Input parameters and input, optionally multiple, output parameters and output target.

In my example I specified copy as codec so the streams are copied as-is, without reencoding. I used map to map video streams 1 and 2 of the first input, and default/all audio streams.

The ffmpeg reference docs are thorough. The wiki has some more guide, example, and explanatory docs.