[FFmpeg-trac] #10374(avcodec:new): Problems to decode certain h264 keyframes with D3D11VA and DXVA2 hw acceleration

[FFmpeg]

#10374: Problems to decode certain h264 keyframes with D3D11VA and DXVA2 hw
acceleration
-------------------------------------+-------------------------------------
             Reporter:  Florian      |                    Owner:  (none)
  Grill                              |
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avcodec
              Version:  6.0          |               Resolution:
             Keywords:  H264 dxva2   |               Blocked By:
  d3d11va                            |
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  1            |
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Comment (by Balling):

 >why is dxva2_h264 just not overriding this limit like the dxva2_hevc
 decoder for example

 It should, I agree, that is the bug.


 >What actually is the advantage of such a small slice limit and why is
 this limit throttling the capability of the h264 DXVA2 and D3D11VA
 decoder?

 That constant (MAX_SLICES) is used while generateing the tables on compile
 time, which uses memory in the binary and thus in RAM. The problem is that
 memory is used many many times. Now the SW decoder needs to preparse the
 bitstream anyway for HW decoder, but it does bot use those tables for
 decoding.
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Ticket URL: <https://trac.ffmpeg.org/ticket/10374#comment:3>
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