[mythtv-users] Testing the HDTV Waters

matt mead m-mythtv at goof.com
Thu May 4 11:56:59 EDT 2006


Calvin Harrigan wrote:
> I've been using Mythtv with SD for years now.  I've decided to try HD, 
> there are quite a few OTA HD channels available in the area.  I browsed 
> through the list looking for minimum configurations needed to play back 
> HD.  The specs seemed a bit high.  My current setup is an Athlon XP 1800 
> with a FX5200 video card, 512 Megs ram. 360 gigs storage.  According to 
> what I've read, what I have is not powerful enough.  But being stubborn 
> I downloaded a couple HD clips.  One in mpeg and one in wmv format,1080i 
> and 720p respectively.  Suprisingly enough both clips played 
> flawlessly.  I was blown away by what I've been missing with HD.  The 
> concern is that I played the clips using the mplayer from within 
> mythtv.  Is the mythtv built in player able to play HD as efficiently?  
> The native format of the tv it's connected to is 1280 x 720 via 
> dvi->hdmi.  So the 1080i was scaled.  Does anyone else have a similar 
> low end setup that is using hd successfully?  Is an 1800 just too slow?  
> Any comments appreciated.

First off, are you talking CPU model or CPU Mhz?  I was capable of playing 720p 
perfectly on an Ahtlon XP @1733Mhz, 512M ram, and an FX5200, using mythtv.  For 
1080i playback, mplayer would do it fine, but I would get the occasional glitch 
in mythtv when the CPU was asked to do something else.  CPU usage tended to be 
around 85-90% for playing of 1080i using bob deinterlacing.  The important 
thing to note is that I was using XvMC.  This was all with mythtv .18.1, and 
XvMC worked fine with the 7xxx nvidia driver I was using at the time.  That 
said, I'm now running on the .19-fixes branch on much faster hardware (Athlon 
64), and having to do software-only decoding with xv scaling.  For the life of 
me, regardless of nvidia driver version, I cannot get XvMC going with my nvidia 
6200.  With software decoding, I cannot get the CPU usage consistently below 
92-95% with bob deinterlacing, though kernel and linear blend result in 50-65% 
CPU usage for 1080i.

I'd say give it a shot.  I wonder if anyone has a script to "import" a file as 
a mythtv recorded program.  If you can find something like this, grab a real 
mpeg2 stream and try it out:
http://www.eff.org/broadcastflag/LotRclip2-mpg.torrent

This is a Lord of the Rings clip the EFF hosts a torrent for so you can 
determine if your computer can handle it.  WMV really isn't going to tell you 
much in terms of whether your computer will properly handle MPEG2 at those 
resolutions and bitrates.

I personally think if you're talking 1800Mhz, you have a strong chance of 
getting HDTV to playback adequately, assuming you can use XvMC.  I wouldn't 
expect the frontend to do much else, though, as it will likely cause stuttering 
when it does.


-matt

-- 
matt mead

http://collectivity.goof.com/


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