[FFmpeg-user] Python / Qprocess misfires commands.

Moritz Barsnick barsnick at gmx.net
Tue May 18 10:33:57 EEST 2021

On Mon, May 17, 2021 at 09:19:46 +0200, Bouke wrote:
> > You will have to show/look at the console output of both commands.
> > (It's there for a reason, and most likely says what the issue is.)
> I know, but there was ’nothing’ on stdErr / stdOut.

Then you're capturing your output incorrectly.

> It turns out that FFmpeg crashes, nothing wrong with the command line.
> QProcess sees an error, and either QProcess terminates FFmpeg (I don’t think so) or FFmpeg crashes by itself.

If QProcess terminates it unconditionally, there's nothing we can do(?).
If ffmpeg crashes, that's bad. You would have to convince your system
to create a core dump, and would have to look at a backtrace. (Or run
ffmpeg within gdb.)

> in Python:
> cmd = "bash"
> args = ["-c", "/Applications/ffmpeg -loglevel trace -report -f avfoundation -i :0 /Volumes/Data/test.mov"]

Do you need to run it in bash? Can you not set cmd to "ffmpeg" and
properly pass the arguments?


More information about the ffmpeg-user mailing list