[FFmpeg-user] Overlaying Teletext, getting jerky video

Nicolas George george at nsup.org
Sun Dec 15 14:54:00 CET 2013

Le quintidi 25 frimaire, an CCXXII, JULIAN GARDNER a écrit :
> Any
>  ideas on why frames are being dropped? I really think that there should
>  be the correct frames from the teletext engine to keep the overlay
> system running.

There are a number of possible reasons; they mostly boil down to the
timestamps of the subtitles being out of sync. If you can not make the
source sample itself available, you can try to provide the following

* The first few video and teletext packets, as shown by ffprobe

* The first few video and subtitles frames, as shown by ffprobe

* The first few video and overlay frames inserted in the filter. For that,
  use the showinfo filter:

  -filter_complex "[0:s] showinfo, scale=1280:720 [sub] ; [0:v] showinfo
  [vid] ; [vid][sub] overlay"


  Nicolas George
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