[mythtv-commits] Ticket #10749: HDPVR playback on mac-mini stutters under mythtv 0.25

MythTV noreply at mythtv.org
Sun Jun 3 15:17:52 UTC 2012

#10749: HDPVR playback on mac-mini stutters under mythtv 0.25
 Reporter:  sean.whitney@…                       |          Owner:
     Type:  Bug Report - General                 |  jyavenard
 Priority:  minor                                |         Status:
Component:  MythTV - Video Playback              |  assigned
 Severity:  medium                               |      Milestone:  unknown
 Keywords:  mac-mini, 0.25, HDPVR, stutter,      |        Version:  0.25
  1080                                           |     Resolution:
                                                 |  Ticket locked:  0

Comment (by jyavenard):


 spent a bit of time tonight tracking what's going on.
 Good news is that it's not the VDA decoder that changed for the worse
 between 0.24 and 0.25. VDA can't decode this video properly

 Note that video plays perfectly on a mid-2011 macbook air with an i5 dual-
 core 1.7GHz processor with almost all profiles tested.

 on the default CPU+ profile, CPU usage oscillates between 58 and 65% with
 a peak at 74.2%.
 on the Normal profile, CPU usage oscillates between 76 and 80% with a peak
 at 90.6%
 Using the OpenGL painter, drops those figure by 2-3%

 The CPU+ profile is actually a blank one, with no configuration
 whatsoever, so you get a playback with the bare minimum with no

 In 0.25, 64 bits build, the CPU+ profile doesn't exits. Must use OpenGL
 painter due to some issues with Qt 4.8
 Normal profile, CPU usage oscillates between 70-74% with a peak at 76%
 OpenGL normal, CPU usage oscillates between 90-110%
 OpenGL slim, CPU usage oscillates between 75-85% with a peak at 82%

 i couldn't test with any opengl playback on 0.24, all i would get is a
 white screen.

 So really, 0.25 doesn't have much loss of performance for its video
 playback, quite the opposite. The main issue is more that the new default
 profiles are far more CPU intensive than what the old ones used to be ;
 and the mac mini was borderline in being able to play them.

 The best playback performance can be achieved like so:
 Go into Setup -> Video -> Playback

 go to page 3/10
 Select "Add New".
 For the "Enter playback Group Name", enter "nothing" . Or whatever doesn't
 next, next... finish

 You'll get the lowest possible quality of playback using onefield
 deinterlacer which gives you only half the vertical resolution.

 but that's all this mac mini can handle.

 using Linux and VDPAU would give you much better experience and quality...
 it's a great frontend (I use mine under ubuntu)

 I'll try to get mythtv to build in 32 bits and using Quartz. it's looking
 like the quartz code is currently broken in master, plus you have to use
 Qt 4.6 to get the old carbon support...

Ticket URL: <http://code.mythtv.org/trac/ticket/10749#comment:19>
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