[FFmpeg-user] Transform dvdsub to png

[Nicolas George]

Thomas Ledoux (12024-07-21):
> I put the subtitle stream first so that the length of the "video" is driven
> by it, and I overlay a black transparent video. I end up having thousands
> of images (25 per second, of course) but they are all repetitions and only
> changing when the subtitle changes. So I wonder now how to only have as
> many images as there are different subtitles. Should I try a decimation ?
> This seems a lot of processing...

Overlaying transparent over the subtitles was a smart idea.

Hum. I realize you probably do not need to overlay anything: the trick
is to get the subtitles into a filter chain, so that ffmpeg converts it
to video: the showinfo filter should be enough to force the conversion.

Also, do not forget -vsync vfr, otherwise the image2 muxer will be
duplicating the frames.

> Le dim. 21 juil. 2024 à 13:57, Nicolas George <george at nsup.org> a écrit :

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Regards,

-- 
  Nicolas George