ffmpeg -i "concat:VTS_01_1.VOB|VTS_01_2.VOB" -c:vlibx264 -c:a aac -strict experimental -q:a 100 output.mp4

$FFMPEG -i mytestmovie.mkv
...
Stream #0:0(eng): Audio: ac3, 48000 Hz, stereo, s16, 384 kb/s (default)
Stream #0:1(fre): Subtitle: subrip (default)
Stream #0:2(eng): Subtitle: subrip
Stream #0:3(eng): Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
...
 
$FFMPEG -i mytestmovie.mkv -vn -an -codec:s:0:1 srt sub.srt

ffmpeg -i <input>.mkv -sub_charenc WINDOWS-1250 -i Intouchables.srt -vcodec copy -acodec copy -scodec srt -metadata:s:s:0 language=ces <output>.mkv