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high cpu usage (prebuffering pause) with mythtv hd playback
PostPosted: Fri Mar 23, 2007 3:05 pm Reply with quote
puterguy
 
Joined: 23 Mar 2007
Posts: 13




I am getting very high cpu usage (mythfrontend ~70%, Xorg ~15-20%) when I am either watching or playing back HD programs.

This gives me "prebuffering pause"s about once a second resulting in jerky playback. I don't have this problem when watching digital channels that are not hd. (Nor do I have the problem when using my old analog tv card).

Interestingly, the mythbackend usage remains minimal whether during recording or playback (2-5%). This in contrast to my old analog card that used about 30-50% cpu for mythbackend.

I get similar high cpu usage with xine and mplayer though the playback under xine is a little less jerky (probably because I think it is just smarter about dropping frames).

My setup is as follows:
pchdtv-5500
Intel P4 2.8GHz CPU (533MHz bus)
GeForce 4 Ti 4600 graphics card with latest 9631 drivers
Fedora core 6 with 2.6.19 kernel
hdparm shows my disk can read at 52 MB/sec
1.5 GB DDR333 RAM

Enabling libXvMCNVIDIA (by adding 'libXvMCNVIDIA_dynamic.so.1') to my /etc/X11/XvMCConfig file only makes the stuttering worse with many more "prebuffering pause" errors.

I would have thought that a 2.8Ghz CPU together with a GeForce4 Ti 4600 would be sufficient to playback hdtv.
So, what configuration/software changes can I make to fix this or is my hardware just too "slow" for this task?

Any thoughts?
Thanks!
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PostPosted: Fri Mar 23, 2007 3:06 pm Reply with quote
puterguy
 
Joined: 23 Mar 2007
Posts: 13




One other thing:
I am using mythtv 0.20 from the ATrpms repo.
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PostPosted: Fri Mar 23, 2007 9:01 pm Reply with quote
bzlxj
 
Joined: 15 Feb 2007
Posts: 16




are you using the nvidia drivers from atrpms? I couldn't get the binary nvidia driver to work, so I installed nvidia packages from atrpms (roughly following wilsonet.com) and saw my HD playback system load go from 100% (on Athlon64 3400) to about 10%. The rpms also don't require the system to shut down the Xserver. Only a logout or Ctrl+Alt+Backspace to restart.

I am funning Fedora Core with an MX4000.
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PostPosted: Sat Mar 24, 2007 4:58 pm Reply with quote
puterguy
 
Joined: 23 Mar 2007
Posts: 13




Yes -- I am using the ATrpms 9631 pre-compiled drivers.
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PostPosted: Mon Mar 26, 2007 6:42 am Reply with quote
bzlxj
 
Joined: 15 Feb 2007
Posts: 16




puterguy wrote:
Yes -- I am using the ATrpms 9631 pre-compiled drivers.


The other thing I had to do was change the frontend configuration. I had monkeyed with the playback settings and changed it to XvMC which still left a huge processor load. Changing back to Standard fixed that. Also, if I use extra audio buffering, I get buggy crackly playback.
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Same Issue
PostPosted: Mon Apr 09, 2007 5:23 pm Reply with quote
jwoolf
 
Joined: 09 Apr 2007
Posts: 1




I get the same thing on my setup. I think that I am on the hairy edge of being able to see HD stuff. I can't actually view HD in mythTv. I have to do it with mplayer and turn on frame drop. It works pretty well with 720p stuff and struggles with 1080i. It also doesn't always stutter like that. It will work fine for a while and then it will start. I am not sure if it is an over heating issue or a hard drive issue or a driver issue. I just bought a 5500 nvidia card and am thinking the the vxmc will help with the hd stuff, and I will have the correct drivers for my graphics card instead of the fglrx drivers that are generic . what you posted makes me nervous though. I'll let you know if I get it working.

_________________
AMD Atholon 2800
PCHDTV 5500
ATI All In Wonder 9800
ASUS mobo
512 mb RAM
Hapauge 150
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PostPosted: Tue Apr 10, 2007 1:50 pm Reply with quote
electronikjunkie
 
Joined: 11 Dec 2006
Posts: 15




The best playback with XvMC I've seen was from compiling the latest Nvidia drivers. If your using Ubuntu check out a script called Envy, which can be found here: http://www.albertomilone.com/nvidia_scripts1.html

If your using something else, just download the latest Nvidia driver and follow do something like this: http://ubuntuforums.org/showthread.php?t=296933

I just make sure /etc/X11/XvMCConfig has: libXvMCNVIDIA_dynamic.so.1 in it, turn on Standard XvMC in Mythfrontend, and turn on Bob deinterlace. What also might help is disabling all hardware you are not using, in order to free up IRQs.
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high cpu usage (prebuffering pause) with mythtv hd playback
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