[FFmpeg-trac] #9377(undetermined:new): QSV MPEG2 => H264 transcode PSNR dropped by 32%

[FFmpeg]

#9377: QSV MPEG2 => H264 transcode PSNR dropped by 32%
-------------------------------------+-------------------------------------
             Reporter:  eero-t       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Between following FFmpeg commits:
 * 2021-06-19 2cf95f2dd9: lavfi/dnn_backend_openvino.c: fix crash when
 target is not specified
 * 2021-06-20 efc22e63e5: lavfi/vf_vpp_qsv: fix the time_base for outlink

 PSNR for following transcode operation:
 {{{
 $ ffmpeg -hwaccel qsv -qsv_device /dev/dri/renderD128 -c:v mpeg2_qsv -i
 1920x1080i_29.97_20mb_mpeg2_high.mpv -c:v h264_qsv -b:v 6000K
 -compression_level 7 -an -vframes 2400 -y 0024_HD17i7_1.0.h264
 }}}

 Has dropped by 32%, as measured by:
 {{{
 $ ffmpeg -i 1920x1080i_29.97_20mb_mpeg2_high.mpv -i 0024_HD17i7_1.0.h264
 -an -vframes 1199 -filter_complex psnr -f null -
 }}}

 (I'm using fewer frames in PSNR check than for transcode, because there
 were odd results if all frames are used for PSNR calcuation.)
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9377>
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