[FFmpeg-trac] #3859(undetermined:new): mp4: start_time never zero

[FFmpeg]

#3859: mp4: start_time never zero
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             Reporter:  blacktrash   |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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Comment (by blacktrash):

 Replying to [comment:6 blacktrash]:
 > Replying to [comment:5 blacktrash]:
 > > With {{{-c:a libfdk_aac -profile:a aac_he -b:a 64k}}} start_time is
 reliably {{{-0.114694}}}, even for audio only.
 > > So I'm gonna ask there, with the fear to be referred back to here.
 >
 > Upon further reflection: encoding to raw aac obviously does not know
 about start time, and muxing audio only e.g. into an m4a container gives
 the abovementioned negative start time.
 > So again, it points to some muxing problem - which is done by ffmpeg.

 And it may cause indeed problems also with the ffmpeg segmenter with fixed
 keyframe positions, as the first keyframe will be outside the
 segment_time_delta which is usually lower than 0.114694 if it's set at the
 recommended value. I notice that the first segment is always longer than
 segment_time.

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Ticket URL: <https://trac.ffmpeg.org/ticket/3859#comment:8>
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