[mythtv-commits] Ticket #10922: [PATCH] OpenGL: Speed up transfer of packed images to texture buffer

[MythTV]

#10922: [PATCH] OpenGL: Speed up transfer of packed images to texture buffer
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 Reporter:  Lawrence Rust        |           Type:  Patch - Feature
  <lvr@…>                        |       Priority:  minor
   Status:  new                  |      Component:  MythTV - Video Playback
Milestone:  unknown              |       Severity:  medium
  Version:  Master Head          |  Ticket locked:  0
 Keywords:  OpenGL texture       |
  optimize                       |
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 I have observed that OpenGL TV playback can consume large amounts of CPU
 time making it unrealistic for some systems.

 Profiling playback shows that, for interlaced content, the main overhead
 is the function pack_yv12interlaced which takes around 23mS using MMX
 instructions on an Intel i5 661 @ 3.33GHz using onboard graphics with
 Linux 3.4 KMS.  With other processing overheads the VideoLoop exceeds 40mS
 causing frames to be dropped.

 Further profiling shows that the main overhead is in writing to the
 texture buffer which is situated in graphics memory.  This patch coalesces
 all writes to the texture buffer into one burst and reduces the time taken
 by pack_yv12interlaced to 12mS using MMX and 15mS without - a reduction of
 ~300%

 Using this patch, playback of interlaced content is smooth and no frames
 are dropped.

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Ticket URL: <http://code.mythtv.org/trac/ticket/10922>
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