[Libav-user] libx264 randomly causing image tearing

Nicolas George george at nsup.org
Wed Jun 15 21:12:37 CEST 2016

L'octidi 28 prairial, an CCXXIV, DeHackEd a écrit :
> Everything is working fine except for one anomaly. Occasionally I get this
> "tearing" effect (screen shot link at bottom of message) for a split
> second where it looks like the top portion of the frame, usually around
> 1/3 of it, looks like a frame from another part of the video. It is most
> noticeable around scene cuts but otherwise doesn't have any pattern. Just
> a glitch of sorts every few seconds.

> Switching to ffv1 I don't see any issues in the output so I'm fairly
> certain it's an libx264 or other encoding side issue.

I find that very unlikely, x264 is an extensively tested library and the bug
you describe does not seem subtle.

It looks like a threading issue to me, in fact: application replacing the
frame data with the next frame while x264 is still accessing it. Since the
FFV1 encoder does not do frame threading, it would not trigger the issue.


  Nicolas George
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