[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...

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