[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
-------------------------------------+-------------------------------------
             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 bermond):

 This also happens with me. It occurs when capturing a X11 desktop and
 using {{{-framerate}}} as an input option alongside with {{{-f x11grab}}}.
 When switching {{{-framerate}}} to {{{-r}}} this warning does _not_ appear
 and everything is normal. For example:

 This gives 'Past duration 0.xxxxxx too large' messages:
 {{{$ ffmpeg -video_size 640x480 -framerate 25 -f x11grab -i :0.0+0,0 -f
 alsa -ac 2 -i pulse output.mkv}}}


 This goes fine:
 {{{$ ffmpeg -video_size 640x480 -r 25 -f x11grab -i :0.0+0,0 -f alsa -ac 2
 -i pulse output.mkv}}}

 But the ffmpeg documentation tells to favor {{{-framerate}}} as an input
 option, so this seems to be just a workaround.

 Adding {{{-vf "fps=25"}}} seems to also fix this, but sometimes you cannot
 use it in the same ffmpeg command. For example, when already using a
 {{{-filter_complex}}} option.

 Using ffmpeg git master.

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Ticket URL: <https://trac.ffmpeg.org/ticket/4643#comment:25>
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