[mythtv] XvMC (limited success on unichrome pro)

Brad brad at thethorntons.net
Wed Dec 14 11:08:18 EST 2005

I was able to watch atsc HDTV (1920x1088) on an Epia SP1300,CN400 FE last
evening with roughly 35% CPU.

Last night I upgraded both the FE and BE to the 12/13 SVN. For anyone else
with a similar setup,

all in videoout_xv.cpp on the FE


       if (vld)

I also modified the BE db, xvmc_buffer_settings;

mysql> update  xvmc_buffer_settings set max_surf='10' where id='2';
mysql> update  xvmc_buffer_settings set min_surf='10' where id='2';
mysql> update  xvmc_buffer_settings set decode_num='10' where id='2';

This allowed Myth to play both live and recorded broadcast HDTV without
immediately crashing, although it did hang,not respond to keystrokes, and
had many prebuffering errors.  Some channels worked better than others with
the same resolution. It seemed to play best at the beginning of a LiveTV
stream and degrade over time.

It will be a few days before I can continue trying to profile the behaviour.
A couple things I need to look at are the memory, I was using 90% of the
512MB, and I'm going to try a PCI ethernet card as I don't trust the
ethernet and video sharing IRQ 10.

A question for the development teams, does the FE use the backend db table
which contains the XVMC buffer settings, I saw much of those hard-set in the

Hope this might help the few other people on the list get closer.


-----Original Message-----
From: mythtv-dev-bounces at mythtv.org [mailto:mythtv-dev-bounces at mythtv.org]
On Behalf Of Ivor Hewitt
Sent: Monday, December 12, 2005 8:19 AM
To: Development of mythtv
Subject: Re: [mythtv] XvMC

Dan Pou wrote:
> So success stories with unichrome pro and hdtv are limited to 
> mplayer/xine because of the surface requirements for all the OSD stuff 
> in Myth presently?
Well I don't have an hdtv source so all testing has been with miscellaneous
mpegs. If I have time I'll see about playing with watching one of them
through myth.

You could try reducing the number of surfaces allocated in videoout_xv.cpp
from the current 16 for vld and see what you get then.

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