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I want to split input video, scale each stream using different parameters and add subtitles to each output, using the same parameters. I can do it repeating subtitles filter in each chain, can I avoid this duplication?

ffmpeg \
    -i input.mp4
    -filter_complex "[v:0]split=2[v480][v720];
[v480]scale=858x480,subtitles=sub.srt:force_style='Fontsize=18,MarginV=15'[o480];
[v720]scale=1280x720,subtitles=sub.srt:force_style='Fontsize=18,MarginV=15'[o720]" \
    -map [o480] -c:v libx264 -b:v 2000k -bufsize:v 3000k -map 0:a -c:a aac -b:a 128k -ac 2 480.mp4 \
    -map [o720] -c:v libx264 -b:v 4000k -bufsize:v 5000k -map 0:a -c:a aac -b:a 128k -ac 2 720.mp4

I this example I want to avoid repeating subtitles=sub.srt:force_style='Fontsize=18,MarginV=15', is it possible?

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Apply the subtitles filter before the split. Note that subtitles will be, proportionally, the same size in each output stream.

-filter_complex "[0:v]subtitles=sub.srt:force_style='Fontsize=18,MarginV=15',split=2[v480][v720]; [v480]scale=858x480[o480];[v720]scale=1280x720[o720]"

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  • Sure, but if I want video quality to be lower, I don't want the subtitles quality to degrade, that's why I make subtitles burning after scaling – fantom May 1 '20 at 17:55
  • Then you'll need to apply subtitles twice – Gyan May 1 '20 at 18:18

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