[FFmpeg-devel] [PATCH] pthread_frame: do not attempt to unlock a mutex on the wrong thread

[wm4]

On Fri, 24 Mar 2017 18:53:41 +0100
Michael Niedermayer <michael at niedermayer.cc> wrote:

> On Fri, Mar 24, 2017 at 01:47:10PM +0100, wm4 wrote:
> > async_mutex has is used in a very strange but intentional way: it is
> > locked by default, and unlocked only in regions that can be run
> > concurrently.
> > 
> > If the user was calling API functions to the same context from different
> > threads (in a safe way), this could unintentionally unlock the mutex on
> > a different thread than the previous lock operation. It's not allowed by
> > the pthread API.
> > 
> > Fix this by emulating a binary semaphore using a mutex and condition
> > variable. (Posix semaphores are not available on all platforms.)
> > ---
> >  libavcodec/pthread_frame.c | 41 +++++++++++++++++++++++++++++++----------
> >  1 file changed, 31 insertions(+), 10 deletions(-)  
> 
> this breaks flac
> 
> make -j12 ffmpeg && ./ffmpeg -i ~/tickets/4421/testwav_cut.wav out.flac ; ./ffmpeg -i out.flac -f null -
> https://trac.ffmpeg.org/attachment/ticket/4421/testwav_cut.wav
> 
> Input #0, flac, from 'out.flac':
>   Metadata:
>     ENCODER         : Lavf57.67.100
>   Duration: 00:00:10.00, start: 0.000000, bitrate: 912 kb/s
>     Stream #0:0: Audio: flac, 44100 Hz, stereo, s16
> Stream mapping:
>   Stream #0:0 -> #0:0 (flac (native) -> pcm_s16le (native))
> Press [q] to stop, [?] for help
> Output #0, null, to 'pipe:':
>   Metadata:
>     encoder         : Lavf57.67.100
>     Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
>     Metadata:
>       encoder         : Lavc57.86.103 pcm_s16le
> Assertion ret <= avpkt->size failed at libavcodec/utils.c:2507
> Aborted
> 
> [...]

I get:

testwav_cut.wav: Invalid data found when processing input

Can't reproduce.