[FFmpeg-trac] #4643(undetermined:reopened): Multiple "Past duration 0.XXXXXX too large" and "dup=0 drop=1" messages when reencoding a H.264 source to x264

[FFmpeg]

#4643: Multiple "Past duration 0.XXXXXX too large" and "dup=0 drop=1" messages
when reencoding a H.264 source to x264
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             Reporter:  birdie       |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  minor        |                Component:
              Version:  git-master   |  undetermined
             Keywords:  dts          |               Resolution:
  regression                         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by michael):

 The "2MB" file is a h264 in flv stream which is at the h264 level marked
 as 30fps. At the flv level as 15fps from its timestamps. 15fps is the
 correct value for the part of the video provided.
 Maybe it contains 30fps content later, the video is truncated so that is
 just a guess.

 What exactly is the bug report about ? (this question is for the original
 report not any possibly unrelated issues showing similar error messages,)

 That FFmpeg guesses input to be 15fps that seems 15fps at the begin ?
 A human looking at the first 2mb would make the same choice likely if he
 is faced with choosing a fps value for converting to constant fps.

 That FFmpeg produces some warning/error messages ?

 That FFmpeg drops frames when it converts 30fps parts to 15fps ?
 That is what it has to do at that point, no real choice.

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Ticket URL: <https://trac.ffmpeg.org/ticket/4643#comment:26>
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