[mythtv-users] Performance issue

Matt Vollmar matt at vollmars.com
Fri Oct 8 12:50:15 UTC 2004

Hi Mythical World,

First of all, I add my thanks to the long list that has already 
accumulated.  I'm sure we will soon have to start a mailing list just 
for thanks soon.

I just built a new box:
- Shuttle SS51G V.2.0
- Celeron 2.4 GHz
- 512 MB PC2700 DDR RAM
- Western Digital 120 GB HD (8MB Cache, 7200 RPM)
- PNY NVidia MX440 64MB DDR AGP (6111 Drivers)
- ATI TV Wonder PCI
- External DVD Writer via USB (for boot) or IEEE1394
- Mandrake 10.0 upgraded to Cooker (so basically 10.1)
- MythTv with all plugins from the site - CVS version
   -- Alsa AND OSS compiled in because I wasn't sure if that was my prob
   -- XvMC compiled in because I have the MX440

Rules the Universe except for one thing:  I cannot watch Live TV without 
the infamous "prebuffering pause".  I've tried a bunch of different 
configs with the way it captures, the way it decodes, etc.  I even 
started to wonder if it was btaudio, since I use that to capture the 
audio.  I started to watch the system when I was capturing movies, and 
it runs at about 70-80% (I use higher quality for these) and watching at 
about 30%.  I have captured a little bit of sar to prove my point:

Watching a Recording
08:05:34 PM       CPU     %user     %nice   %system   %iowait     %idle
08:06:04 PM       all     30.14      0.00      5.79      0.00     64.07

Recording a Show
08:09:06 PM       CPU     %user     %nice   %system   %iowait     %idle
08:09:11 PM       all     81.11      0.00      1.99      0.20     16.70
08:09:16 PM       all     84.57      0.00      1.20      0.00     14.23
08:09:21 PM       all     77.45      0.00      1.40      0.20     20.96

The recording seems to be the problem.  Here are my settings:
TV Playback:
- Deinterlace with Bob (2x) -- I figure since I have XvMC compiled in 
(kernel makes no difference)
- Use XvMC Hardware Decoding
Software Encoders -> Live TV
- 480x480 (I would really like 640)
- MPEG-4, bitrate=3000, max qual=2, min qual=15, max diff=3, the rest is 
- MP3, 32000, Quality=7

If you need more info, let me know.  This is all the info I know to 
check for.

Thanks in advance.


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