How to specify/map English only subs in ffmpeg

[wallywalters]

I thought

-map 0:s:language:eng

would allow me to map the English subtitle streams but it doesn't work. The string

-map 0:m:language:eng

does work, but it acts on [U]all[U] streams, and causes unpredictable behavior. Is there another way I can process an MKV file and retain only the English subtitles? Thanks.

[sneaker]

mkvmerge -o "output.mkv" -s eng "input.mkv"

(I assumed you want to keep video and audio, not only English subtitles.)

[wallywalters]

I wish to keep the first video stream (if there are more than one), the English audio streams (only), and the English subtitles (only). My ffmpeg command line works in the first two cases but not for the subtitles.

[sneaker]

mkvmerge -o "output.mkv" -d 0 -a eng -s eng "input.mkv"

But this only works with assuming the first video track has TrackID 0 (should be true in 99.9% of all cases). Unfortunately, mkvmerge doesn't have options like -map 0:v:0.

[wallywalters]

Thanks.