[FFmpeg-trac] #7706(avcodec:open): 20-30% perf drop in FFmpeg (H264) transcode performance with VAAPI

[FFmpeg]

#7706: 20-30% perf drop in FFmpeg (H264) transcode performance with VAAPI
-------------------------------------+-------------------------------------
             Reporter:  eero-t       |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  vaapi        |               Blocked By:
  regression                         |
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
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Comment (by fulinjie):

 Currently, vaapi encodes a pic if all its referenced pics are ready,
 and then outputs it immediately by calling
 vaapi_encode_output(vaSyncSurfac).

 When working on output procedure, hardware is be able to cope with
 encoding
 tasks in the meantime to have better performance.

 So there is a more efficient way to encode the pics whose refs are all
 ready
 during one receive_packets() function and output the pkt when encoder is
 encoding
 new pic waiting for its references.

 It's what vaapi originally did before the regression, and the performance
 could be
 improved for ~20%.

 CMD:
 ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128
 -hwaccel_output_format vaapi -i bbb_sunflower_1080p_30fps_normal.mp4
 -c:v h264_vaapi -f h264 -y /dev/null

 Source:
 https://download.blender.org/demo/movies/BBB/

 Before:
     ~164 fps
 After:
     ~198 fps

 However, it didn't totally meet the performance benchmark before the
 regression in my experiment.

 Hi Eero,

 Would you please help to verify this patch:
 https://patchwork.ffmpeg.org/patch/16156/

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Ticket URL: <https://trac.ffmpeg.org/ticket/7706#comment:9>
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