[FFmpeg-trac] #604(avcodec:new): Multithreaded ffmpeg decode with DXVA2 hangs

[FFmpeg]

#604: Multithreaded ffmpeg decode with DXVA2 hangs
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             Reporter:  IMarshal    |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by IMarshal):

 reimar:

 Thanks for your reply.

 I agree that multithreaded decoding and DXVA don't really make sense
 together.  Our problem however is similar to VideoLan, in that we decide
 on the pixel format well after opening the decoder.  So by the time we
 know that we really wanted one thread, it's already too late.

 It would be fantastic if ffmpeg would gracefully revert to using a single
 thread under these scenarios.  Hanging is clearly suboptimal.  :-)  So I
 think we agree on that as well.

 Unfortunately, I find debugging ffmpeg on Windows pretty challenging,
 given that mingw builds don't have symbolic information as per what the
 standard platform tools expect.  Do you have any tips or hints on how best
 to debug this?

 If any of the ffmpeg core developers were to attack this problem, I've be
 overjoyed to help in terms of providing help with repro cases, builds of
 Plex and so forth.  I'm sure we're not the only user of ffmpeg hitting
 this issue, so it would be great to get it fixed for everyone.

 Thanks again.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/604#comment:4>
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