[FFmpeg-trac] #8696(avcodec:new): enhancement: more neon accerleration for vc-1

FFmpeg trac at avcodec.org
Sat May 30 21:00:18 EEST 2020

#8696: enhancement: more neon accerleration for vc-1
             Reporter:  spotter  |                     Type:  enhancement
               Status:  new      |                 Priority:  normal
            Component:  avcodec  |                  Version:  git-master
             Keywords:  vc-1     |               Blocked By:
             Blocking:           |  Reproduced by developer:  0
Analyzed by developer:  0        |
 Summary of the bug:

 comparing x86 optimizations to arm, it seems there are a number of
 optimizations that exist in the x86 space that don't exist for arm.

 I've noticed this on my Sony Android TV which seems to be defective in
 that even though it has support for VC-1, it's not exporting that support
 via mediacodecs.

 see: https://github.com/CiNcH83/bravia_atv2/issues/4 (and even their built
 in player is buggy with it see

 so decided to explore what could be done to optimize vc-1 software

 I cam across the samsung paper that shows major improvements:
 http://www.ncc.org.in/download.php?f=NCC2010/B2_3.pdf (in digging into the
 asm hooks that ffmpeg's video decoder has, I'm guessing this paper isn't
 new to ffmpeg's developers)

 and then dug into ffmpeg where I saw that it seems that there a lot more
 x86 hooks that do't exist for arm (example loopfilter).  I'm wondering if
 this is a conscious decision? (i.e. because of limitations of neon it
 can't be done effectively) or an oversight and in truth arm should have an
 equivalent set of vector instructions like x86?

Ticket URL: <https://trac.ffmpeg.org/ticket/8696>
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