[FFmpeg-trac] #4062(ffmpeg:new): sub2video overlay fails with negative starting timestamp and -copyts

[FFmpeg]

#4062: sub2video overlay fails with negative starting timestamp and -copyts
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             Reporter:  mikaraento  |                     Type:  defect
               Status:  new         |                 Priority:  normal
            Component:  ffmpeg      |                  Version:  git-master
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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 Summary of the bug: If the input starts on a negative time and -copyts is
 given, sub2video causes 'Buffer queue overflow, dropping' messages and
 broken output.

 Although this seems like a minor problem, the problem is easily triggered
 by broadcast input that has non-monotonic timestamps (will try to find a
 simple testcase for that and file a separate ticket).

 I need -copyts to later sync video and audio if there is missing video or
 audio.

 How to reproduce:
 {{{
 $ ffmpeg -y -i negative_pts_sub.ts -copyts -filter_complex
 '[0:0][0:3]overlay[outv0]' -map 0:1 -map '[outv0]' broken.ts
 ffmpeg version N-67065-g2fa08fd Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Oct 23 2014 08:58:30 with Apple LLVM version 6.0
 (clang-600.0.51) (based on LLVM 3.5svn)
 }}}

 The following works:
 {{{
 $ ffmpeg -y -itsoffset 46.944644 -i negative_pts_sub.ts -copyts
 -filter_complex '[0:0][0:3]overlay[outv0]' -map 0:1 -map '[outv0]'
 working.ts
 }}}

 Patches should be submitted to the ffmpeg-devel mailing list and not this
 bug tracker.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4062>
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