[FFmpeg-devel] [RFC] ffmpeg/ffprobe commandline option to av_log_set_callback ?

"René J.V. Bertin" rjvbertin at gmail.com
Wed Mar 20 14:57:12 CET 2013

On Mar 20, 2013, at 14:28, Nicolas George wrote:

> I do not think it is possible to specify a C function pointer as a string on
> the command line.

Only if that function is listed in some lookup table together with its address ... and said address is in the appropriate space.

But that's not what I had in mind. I thought more along the lines to specify a log file name or URI, with a little dedicated function that calls the standard log message format function and then sends the resulting string to the specified destination.
> The -progress option of ffmpeg is designed exactly for that.

I was not only thinking about progress information - that's not generated with av_log, or is it?

> The log output goes to the standard error stream, you can connect this
> stream to any kind of file descriptor you want.

That would work under unix-like OSs, presuming that file descriptors are unique system-wide and not process-specific. I doubt mswin associates a file descriptor with a named pipe's HANDLE, and I also doubt that one can redirect stderr on the popen command line as under unix/linux. I have already hacked some things in the MSVC popen function, I could have a look if there's anything in there that allows to connect a process's error output to a given, open HANDLE.


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