[FFmpeg-trac] #8109(undetermined:reopened): Long loading delay for VfW codecs in Matroska

[FFmpeg]

#8109: Long loading delay for VfW codecs in Matroska
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             Reporter:  Austin       |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
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Comment (by Austin):

 Thank you for investigating so quickly!  This is encouraging.

 Even if the delay is only 4 seconds (Windows only apparently), this still
 causes a Kdenlive or Shotcut video editing project with 30 long clips to
 take an extra two minutes to load.  My multi-cam projects in particular
 bump into this issue.

 I should have added that the older and slower the hardware, the longer the
 MKV parsing appears to take by an exponential amount.  The computer that
 took 20+ seconds is a dual-socket 16-thread 2.4GHz Xeon E5530 from ten
 years ago running Windows 7.  It is not fast by today's standards, but it
 still works great for video editing if using 640x360 proxies.
 Unfortunately, I can't get proxies to use full-range YUV video without a
 flag from a Matroska container, hence this ticket.  But even on my old
 hardware, the AVI and MOV files are still instant in all usage scenarios
 whereas MKV is not.  MKV is somewhat improved on my faster hardware with
 Windows 10, but still never instant.  Perhaps my older hardware is missing
 a CPU instruction set that optimizes things?

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Ticket URL: <https://trac.ffmpeg.org/ticket/8109#comment:4>
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