Opened 12 months ago

Closed 7 months ago

Last modified 7 months ago

#7937 closed defect (invalid)

no explanation of return value of ffmpeg

Reported by: sgerwk Owned by:
Priority: minor Component: documentation
Version: git-master Keywords:
Cc: sgerwk@aol.com Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:
I cannot find a description of the return value of ffmpeg in the man pages ffmpeg.1 and ffmpeg-all.1. As far as I can see, this may be 0=everything fine, 1=error of some kind, 255=killed (SIGINT or SIGTERM). Maybe there are other possible return values.

How to reproduce:

% ffmpeg -i input output
% killall ffmpeg
ffmpeg version 4.1.git Copyright (c) 2000-2019 the FFmpeg developers
built with gcc 8.3.0 (GCC)
configuration: --enable-shared --enable-libdrm --enable-libopencore-amrnb --enable-version3 --enable-libvpx --enable-libcaca --enable-libvorbis --enable-gpl --enable-libxcb --enable-openssl --enable-nonfree --enable-libmp3lame --enable-libxml2
libavutil      56. 28.100 / 56. 22.100
libavcodec     58. 52.102 / 58. 35.100
libavformat    58. 27.103 / 58. 20.100
libavdevice    58.  7.100 / 58.  5.100
libavfilter     7. 55.100 /  7. 40.101
libswscale      5.  4.101 /  5.  3.100
libswresample   3.  4.100 /  3.  3.100
libpostproc    55.  4.100 / 55.  3.100

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

Change History (5)

comment:1 Changed 12 months ago by sgerwk

  • Component changed from ffmpeg to documentation

comment:2 Changed 7 months ago by Balling

  • Resolution set to invalid
  • Status changed from new to closed

Those things are (or should be as I just come after some problems about that) guranteed to be like that by Posix Standards and by linux kernel code. Do not think that should be documented.

comment:3 Changed 7 months ago by cehoyos

  • Keywords return value kill sigterm sigint removed

comment:4 Changed 7 months ago by Cigaes

The standard Unix convention is 0 for success, ≠0 for failure. FFmpeg does not ofcially try to distinguish between the kinds of failure through the return code.

comment:5 Changed 7 months ago by sgerwk

  • Cc sgerwk@aol.com added

I believe this very comment would be just fine for documenting the exit status.

Let me explain my point of view. I wrote a script using ffmpeg to get a file from the Internet. This may fail or not, and the obvious thing to check is the exit status of ffmpeg. I was I bit surprised to see that the exit status was not always the same, yet no explanation was given in the man pages. Even basic commands like ls(1) and find(1) have a short paragraph explaining the obvious like 0=ok otherwise=fail. Lacking that, I would have resorted to the current behaviour of ffmpeg, and I would have been wrong as you pointed out. That would have been avoided by a paragraph in ffmpeg-all(1):

EXIT STATUS

The exit status of ffmpeg is 0 if the command completed successfully and different from zero otherwise. Avoid relying on specific values in the latter case as they are subject to change.

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