[mythtv-commits] Ticket #6986: max CPUs setting for Multithreading ffmpeg h264 has no affect.

[MythTV]

#6986: max CPUs setting for Multithreading ffmpeg h264 has no affect.
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 Reporter:  reidjr_at_lineone_net  |       Owner:  ijr    
     Type:  defect                 |      Status:  new    
 Priority:  major                  |   Milestone:  unknown
Component:  MythTV - General       |     Version:  head   
 Severity:  medium                 |     Mlocked:  0      
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 Setting max CPUs no longer allows multi-threading on playback of BBC-HD.

 I was updating my loop-filter skipping patch for trunk,  #4653 and while
 testing it I noticed that without the patch, I was seeing only 1 core of
 my core2duo e4300 used.

 The strange thing is that the patch has not been incorperated, but the
 multi threaded support is there. I've updated the patch for trunk. Without
 the patch, multithreading h264 doesnt work, whatever you set max CPUs to.
 With the patch Setting the loopfilter option to off, doesn't save any
 overall cpu load, but does allow multithreading to work. Looks like either
 ffmpeg or underlying code has changed, as the overall cpu load is
 comparible to the performance I used to see with the loopfilter disabled.

 So the behaviour I saw was :

 using trunk 21651:[[BR]]

 Max cpu = 1  result single threaded 90% cpu load[[BR]]

 Max cpu = 2  result single threaded 90% cpu load[[BR]]


 using trunk 21651 with enc>skiploop = AVDISCARD_ALL added to
 avformatdecoder.cpp:[[BR]]

 Max cpu = 1  result single threaded 90% cpu load[[BR]]

 Max cpu = 2  result multi threaded 45% x 2 cpu load[[BR]]


 So no overall reduction, but multi-threading works.

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Ticket URL: <http://svn.mythtv.org/trac/ticket/6986>
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