[FFmpeg-user] combining concat filter with closed caption extraction

[Leo Butler]

Currently, the only way I know to extract/insert closed captions as a
subtitle stream is in 2 passes. Something like

ffmpeg -i A.ts -i B.ts -filter_complex '[0:0][0:1][1:0][1:1]
concat=n=2:v=1:a=1' C.mkv

ffmpeg -i C.mkv -f lavfi 'movie=C.mkv[out0+subcc]' -map 0 -map 1:s D.mkv

(In practice, A.ts and B.ts are segments from the same file).

Question: Is there a way to reduce this to one pass?

I am using a recent version of ffmpeg compiled from the git repository.

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It may seem odd to want to convert the closed captions to a subtitle
stream, but in my use case, the subtitles are easier to read than the
closed captions.

Leo