[mythtv-users] New motherboard => high CPU, prebuffering pause

Jeff Piazza jeff at jeffpiazza.org
Fri Dec 29 05:00:23 UTC 2006

I recently put together this machine:

AMD 3700+ (socket 939)
ASUS A8V Deluxe motherboard (VIA K8T800 Pro, 5 PCI slots, 4 SATA)
eVGA 6200, 256MB AGP
pcHDTV HD-3000
Hauppauge PVR-150

I was mostly able to get this to work with the binary NVIDIA driver and 
XvMC, but I seemed to be having problems with HD streams recorded while 
playing back another recording.  (There were also some DMA issues with 
the ivtv driver and SATA that seemed to get resolved when I switched to 
the other SATA controller on the board.)  I'm using Myth 0.20, Ubuntu 
Dapper, and a kernel I compiled myself.  I don't remember the 
exact CPU usage, but HD playback in mythfrontend was 20% or less with 

I found several forum posts around claiming that the specific 
combination of NVIDIA driver, AGP graphics card, and HD-3000 could 
result in the HD-3000 losing its tuning lock.  (Can't seem to find a 
reference just now.)  That plus the DMA trouble plus some IRQ sharing 
prompted me to buy a new PCI-e motherboard and graphics card:

MSI K8N Neo4
BioStar 6600LE

Strangely, this new configuration shows extremely high CPU utilization 
(98% in mythfrontend), and constant "prebuffering pause" messages 
during HD playback.  The audio is unintelligible stutter.

Playing back a standard def .nuv file (recorded by my original myth 
box, running 0.18) shows 70% CPU in Xorg, and 19% in mythfrontend.  
However, there are no "prebuffering pause" messages, and the stereo 
audio is normal.

mythfrontend reports the following (for HD playback):

2006-12-28 22:23:43.631 TV: Attempting to change from None to 
2006-12-28 22:23:43.733 DPMS Deactivated
0: start_time: 3618.611 duration: 323.312
1: start_time: 3618.576 duration: 323.306
stream: start_time: 40206.397 duration: 3592.752 bitrate=17858 kb/s
2006-12-28 22:23:44.177 AFD: Opened codec 0x820e070, 
id(MPEG2VIDEO_XVMC) type(Video)
2006-12-28 22:23:44.178 AFD: Opened codec 0x83535d0, id(AC3) type(Audio)
2006-12-28 22:23:44.180 Opening ALSA audio device 'plug:hw:1'.
2006-12-28 22:23:44.270 VideoOutputXv: XvMCTex: Init failed
2006-12-28 22:23:44.270 VideoOutputXv: XvMC Adaptor Name: 'NV17 Video 
X Error: BadMatch (invalid parameter attributes) 8
   Major opcode:  140
   Minor opcode:  14
   Resource id:  0x18b
2006-12-28 22:23:44.292 NVP: Forcing decode extra audio option on.
                         XvMC playback requires it.
2006-12-28 22:23:44.663 The realtime priority setting is not enabled.
2006-12-28 22:23:44.666 TV: Changing from None to WatchingPreRecorded
XvMC: picture structure FRAME
2006-12-28 22:23:44.910 Video timing method: RTC
2006-12-28 22:23:45.437 WriteAudio: buffer underrun
2006-12-28 22:23:45.673 WriteAudio: buffer underrun
2006-12-28 22:23:45.682 NVP: prebuffering pause
2006-12-28 22:23:45.730 NVP: prebuffering pause
2006-12-28 22:23:45.779 NVP: prebuffering pause
2006-12-28 22:23:45.917 NVP: prebuffering pause
2006-12-28 22:23:45.984 NVP: prebuffering pause
2006-12-28 22:23:46.030 NVP: prebuffering pause
2006-12-28 22:23:46.078 NVP: prebuffering pause

I have to confess that I don't know whether the VideoOutputXv and "X 
Error: BadMatch" messages appeared when using the other motherboard or 
not.  I'd appreciate someone who understands them explaining their 
meaning; hopefully they're a clue.

More generally, I'd really like to hear any suggestions on how to 
diagnose this problem.  I'm really stuck for what to do next.

Thanks in advance,

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