[FFmpeg-trac] #6251(undetermined:new): copyts fails badly for negative start time

FFmpeg trac at avcodec.org
Sat Apr 29 14:19:46 EEST 2017


#6251: copyts fails badly for negative start time
-------------------------------------+-------------------------------------
             Reporter:  cehoyos      |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  mpegts dts   |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by ferrys):

 Its not only for negative start time... If you use -copyts - this happens
 because of a timestamp overflow in the MPEGTS(section 3.3) demuxer. Since
 timestamps in MPEG-TS have 33 bits and 16 a frequency of 90 kHz, they
 overflow exactly after 233
 90000  95443:72 s 
 26:51 h.

 after 26h 51 min. ffmpeg going down... please fix it beacause it is
 necessary to use -copyts for preserving audio video sync by transcoding
 udp multiast streams for example... if you not use this parameter you can
 expect bad sync in audio video - small problem in audio track is enough...
 ffmpeg is then not able to hold sync... in cas of clean input stream,
 everything is ok and you can nto use this...

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Ticket URL: <https://trac.ffmpeg.org/ticket/6251#comment:1>
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