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I am trying to add multiple languages of subtitles to a video using ffmpeg. I succeeded in adding 1 language, but can't seem to add a second one. I use this simple script to add english subtitles to my video.

ffmpeg -i %1 -i subs_eng.srt -map 0 -vcodec copy -acodec copy -scodec subrip -metadata:s:s:0 language=English "%~n1"_eng.mkv

In addition, I run another script to add the Dutch subtitles. 

ffmpeg -i %1 -i subs_nl.srt -map 0? -vcodec copy -acodec copy -scodec subrip -metadata:s:s:1 language=Dutch "%~n1"_nl.mkv

But whenever I add the second language, it doesn't seem to do anything. The command terminal shows that ffmpeg is processing the video, but there is only 1 subtitle language available in vlc media player (the first one).

I really want to be able to add it in 2 takes rather than in the same script, as I don't have both languages for all of my video's.

Appa
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2 Answers2

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Without -map for the subtitle stream, ffmpeg will select only one subtitle stream from among all inputs.

ffmpeg -i %1 -i subs_nl.srt -map 0 -map 1 -vcodec copy -acodec copy -c:s:0 copy -c:s:1 subrip -metadata:s:s:1 language=Dutch "%~n1"_nl.mkv

I set codec mode for the existing subtitle stream to copy and subrip for only the new one. This assumes you muxed exactly one subtitle stream earlier.

Gyan
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It is easier in fact. You can add subtitles to a file without removing old ones by

ffmpeg -i input.mkv -i input.srt -map 0 -map 1 -c copy output.mkv

-map x selects all streams from a file so all streams from both files get into the output file. If you add more input subtitle tracks, you need to supply -map 2, -map 3 and so on. See the very conscious and simple Map documentation.

Now more tricky is if you want to properly label these subtitles. You can add

-metadata:s:s:0 language=heb -metadata:s:s:0 handler_name=Hebrew -metadata:s:s:0 title=Hebrew
-metadata:s:s:1 language=eng -metadata:s:s:1 handler_name=English -metadata:s:s:1 title=English

But you need to know the final mapping which will depend on original files ab/presence of subtitles.

Credits to eladkarako.

akostadinov
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