[FFmpeg-trac] #7690(undetermined:new): FFmpeg QSV decode + VPP performance is just a fraction of what one gets with VA-API and MediaSDK

[FFmpeg]

#7690: FFmpeg QSV decode + VPP performance is just a fraction of what one gets
with VA-API and MediaSDK
-------------------------------------+-------------------------------------
             Reporter:  eero-t       |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  qsv          |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by eero-t):

 f I force KBL GT2 GPU to max speed (gt_min_freq_mhz = gt_max_freq_mhz),
 and run just single pipeline, QSV performance doubles, but there's still
 40-50% gap to the other options.

 Same performance gap between QSV & VA-API backends is visible also when
 doing just decode (or decode+downscale):
 {{{
 ffmpeg -hwaccel qsv -qsv_device /dev/dri/renderD128 -c:v hevc_qsv -i
 1920x1080_10bit_60fps.h265 -f null -
 }}}

 I guess when running parallel pipelines, difference is much smaller
 because things hit a another bottleneck that's common with all drivers
 (100% video engine utilization), thereby diminishing the impact of the QSV
 pipeline issue visible when running just one pipeline.

 Note: I've earlier seen VA-API being being much slower than QSV when doing
 1920x540 8-bit HEVC decode, I need to retest that in case there's been
 some change recently in kernel, mediasdk or FFmpeg since, or are things
 resolution dependent.

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Ticket URL: <https://trac.ffmpeg.org/ticket/7690#comment:11>
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