[FFmpeg-trac] #1339(avfilter:new): Auto insert fps filter as adapter for overlay filter inputs with different framerates

[FFmpeg]

#1339: Auto insert fps filter as adapter for overlay filter inputs with different
framerates
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             Reporter:  annorax      |                    Owner:
                 Type:  enhancement  |                   Status:  new
             Priority:  wish         |                Component:  avfilter
              Version:  git-master   |               Resolution:
             Keywords:  fps overlay  |               Blocked By:
  filter                             |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
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Comment (by reimar):

 The most obvious reason why it is not a general solution is that not all
 inputs have a (fixed) framerate or something that is a suitable
 substitute.
 Even in a very simple case of overlaying a 24 fps video with a 25 fps one,
 "equalizing" the fps will not lead to a good result. If you change the 24
 fps one to 25 fps that will result in noticeable stutter once a second,
 for exact results you'd have to go to an insane 600 fps.
 If the overlay filter were taking both timestamps into account you could
 get an _exact_ (though variable fps) output with at most 49 frames per
 second (though those frames would be at very variable intervals and a lot
 of players would have problems displaying it accurately I admit, so the
 win may be questionable in real-world use).

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1339#comment:3>
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