[FFmpeg-trac] #9771(avcodec:open): Small MAX_SLICES makes d3d11va (AVC) not bitperfect and causes artifacts (but not CUDA/NVDEC)

FFmpeg trac at avcodec.org
Sun Jun 19 01:53:50 EEST 2022


#9771: Small MAX_SLICES makes d3d11va (AVC) not bitperfect and causes artifacts
(but not CUDA/NVDEC)
-------------------------------------+-------------------------------------
             Reporter:  Balling      |                    Owner:  (none)
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  d3d11va,     |               Blocked By:
  h264, hwaccel, dxva2               |
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  1            |
-------------------------------------+-------------------------------------
Comment (by Balling):

 >that file does not warn that "MAX_SLICES should be increased", may be
 another bug

 It is a bug. Has to compile reference decoder while changing the
 MAX_NUM_SLICES there (not ffmpeg's MAX_SLICES). Apparently that video has
 41 slices for theat samples (reference decoder does not require it to be a
 power of two). See
 https://code.videolan.org/videolan/vlc/-/issues/26918#note_324215
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9771#comment:2>
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