[FFmpeg-trac] #5048(undetermined:closed): -map 0:v causes segfaults on 2pass libvpx-vp9 on multi video-track file

[FFmpeg]

#5048: -map 0:v causes segfaults on 2pass libvpx-vp9 on multi video-track file
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             Reporter:  kagami       |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  important    |                Component:
              Version:  git-master   |  undetermined
             Keywords:  libvpx       |               Resolution:  invalid
  crash SIGSEGV                      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by cehoyos):

 Replying to [comment:2 kagami]:
 > What version of libvpx do you have? I tried with 1.4.0 and still getting
 the same segfault.

 1.3.0

 > I think the problem is that ffmpeg uses same logfile for two different
 video tracks

 This is possible but unavoidable in other cases, think of a user mistake.

 > which is incorrent; segfault is just the consequence of passing
 corrupted logfile.

 So if I understand correctly (and please do correct me if I am wrong) you
 argue that it is perfectly ok for libvpx to crash if the logfile that is
 passed does not match the source file? Or in other words: If a user
 (accidentally or not) passes a different source file for first and second
 pass the expected result is that libvpx crashes?

 To be more precise: Generally, libraries should never crash on invalid
 input. In this specific case (second pass input file does not match the
 log file) I have argued in the past (#2846) that you are lucky if the
 encoding library crashes: If it does not crash and you get an output file,
 it is most likely broken / very bad quality and you will not notice. In
 any case, all this is outside of the scope of FFmpeg.

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Ticket URL: <https://trac.ffmpeg.org/ticket/5048#comment:3>
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