[mythtv-users] mythfrontend with compositing

[Phil Linttell]

In the following article I noted that the author said that he could get
H.264 VDPAU playback without screen-tearing, and with compositing turned
on, by setting the refresh rate in CompizConfig and enabling "Sync to
VBlank" in nvidia-settings:

http://linuxuserwakizaki.wordpress.com/2010/05/17/the-lucid-lynx-plunge/

Previously, I've only been able to get tear-less playback by disabling
compositing the extensions in xorg.conf, and increasing the CPU
frequency as per the MythTV VDPAU wiki:

http://www.mythtv.org/wiki/VDPAU

However, I figured I'd give it a try with my lowly GeForce 8200 chipset
(Asus M3N78-VM) combined FE/BE, and low-and-behold, it works.... at
least if I disable compositing via Alt-Shift-F12 before starting
mythfrontend.  Still, this is progress because it at least means that I
can use compositing when I'm not watching videos.... and perhaps a more
capable VDPAU chipset might be able to run with compositing on, as the
author claims.

I now start mythfrontend with the following script:

  #!/bin/sh

  # force CPU clock to 1.8GHz, in order to provide memory bandwith
required by VDPAU
  echo "1800000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq

  # turn off compositing, if it's on
  composited='qdbus org.kde.kwin /KWin compositingActive'
  if $composited; then qdbus org.kde.kwin /KWin toggleCompositing; fi

  # start myth
  mythfrontend

  # turn compositing back on
  if $composited; then qdbus org.kde.kwin /KWin toggleCompositing; fi

  # drop minimum CPU clock back down to 1GHz
  echo "1000000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq

Hope this is useful to someone.