On Windows, av.logging messages like crazy, then crash

[beville]

Hey there, thanks putting together this great project. I recently used pyav to as part of a custom video app using PyQt4 on Linux. I'm trying to get the app running on Windows, but have run into a snag with pyav.

I came across this link (https://github.com/MichaelBarz/PyAV/tree/master/dist) in #38 and was able to install the wheel file without any issues. (Running on Windows 10, 32-bit, Python 2.7 (from Anaconda)).

On the first call to av.open(), I start getting a flood of messages like:

av.logging: vasprintf errored on (null): Probing %s score:%d size:%d
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: Format %s probed with size=%d and score=%d
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: ISO: File Type Major Brand: %.4s
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: time scale = %i
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: type: %08x '%.4s' parent:'%.4s' sz: %lld %lld %lld
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: type: %08x '%.4s' parent:'%.4s' sz: %lld %lld %lld
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: ctype= %.4s (0x%08x)
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: stype= %.4s
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: type: %08x '%.4s' parent:'%.4s' sz: %lld %lld %lld
av.logging: vasprintf errored on mov,mp4,m4a,3gp,3g2,mj2: type: %08x '%.4s' parent:'%.4s' sz: %lld %lld %lld

I created a simple test to recreate the problem:

import av

container = av.open('/path/to/video.mp4')
print "Got here 1"

video = next(s for s in container.streams if s.type == b'video')
print "Got here 2", video
print video

count = 0
for packet in container.demux(video):
    for frame in packet.decode():
        frame.to_image().save('frame-%04d.jpg' % frame.index)
        print "saving #", count
        count += 1
    if count > 10:
        break

Sometime the script will complete, other times will crash before writing all, or any of the frames out. In all cases, it floods the console with "av.logging: vasprintf errored on" messages.

Does anyone have any insights into what might be going on? I haven't yet tried to build my own dlls and pyd files, so maybe that would be worth a try. However, that fact that things kinda work means maybe there is something I can do to mitigate things..?

[mikeboers]

My first guess is that there is a subtle difference in the Windows' vasprintf than the Linux one.

You should be able to completely cut off the library logging from the Python logging via:

import av.logging
av.logging.set_level(av.logging.QUIET)

Still seems like a PyAV "bug".

[beville]

Well, bad news is that setting the log level to av.logging.QUIET didn't stop the flood. Good news is that for some reason, after a Windows reboot, neither the test app or my actual application are crashing. If redirect the command to 'nul', things are more or less working perfectly.

When I have time, I'm going to go through the entire ffmpeg build process, and I'll report back. Then at least I'll be able to tweak the pyav source

Thanks!

[beville]

More testing with that downloaded wheel file made it seem like a dead end. I bit the bullet today, and when through the full ffmpeg build, and then was able to generate a functional wheel that I was able to use across different machines. Gonna mark this as closed, and open a new thread with some notes on my experience with the windows build.