[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 kagami):

 >you argue that it is perfectly ok for libvpx to crash if the logfile that
 is passed does not match the source file?

 No, segfault is just the symptom here.

 >Generally, libraries should never crash on invalid input

 Completely agree. This crash should be fixed in libvpx and this issue
 should have a bit different name and description. I just don't have enough
 knowledge to analyze whether ffmpeg correctly encodes two VP9 tracks with
 2pass at the same time (corrupted logfile is just an assumption), so I
 demonstated the most obvious consequence from the user point of view in
 this ticket. It still would be bad if you get output but in bad quality if
 e.g. libvpx can tolerate wrong input.

 I think it might be related to the logfile processing because:
 * I encode two tracks but get only single log file
 * If I encode only 1 track on a second pass, I still get segfault

 I may be complete wrong here though. So ideally I should file crash bug to
 the libvpx first, wait for the fix, make sure library explicitly forbids
 incorrect logs/input, try again. I just thought it would be easier if
 someone at ffmpeg bugtracker could tell whether it's related to ffmpeg or
 just libvpx issue.

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Ticket URL: <https://trac.ffmpeg.org/ticket/5048#comment:4>
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