How do I map -vf subtitles with ffmpeg?

Question

I'm trying to burn in subtitles from this format:

0:0 Video
0:1 English Audio
0:2 Japanese Audio
0:3 English subtitle (default)
0:4 English subtitle (translation only)

Both are subrip. What I usually use is this batch file

ffmpeg -i "foo.mkv" ^
-map 0:0 -map 0:2 ^
-c:a:2 copy ^
-vf subtitles="foo.mkv" ^
"foo_1.mkv"

but it only works if there's one subtitle stream. When I run this on the dual subtitle videos it processes a new video but gives no subtitles.

Answer 1

Use the stream_index / si option to choose the desired subtitles stream. To render the second subtitles stream from foo.mkv:

subtitles=foo.mkv:si=1

See the subtitles filter documentation for more info.