[mythtv-users] Quiet HDTV Hardware

glen martin lists at locutory.org
Fri May 5 20:14:22 EDT 2006

glen martin wrote:
> Marco Nelissen wrote:
>>> I didn't have so much luck with this. For me, the A8N-VM CSM and 3200+ 
>>> could manage SD signals great, but the high-bandwidth HD signals rode 
>>> the edge. From memory (since I'm booted into the wrong OS just now), the 
>>> SD signals ran around 3200 mb/s, but the HD around 17,000+.  The system 
>>> could play HD pretty well, with the occasional stutter, except every now 
>>> and then on starting a program it would go asymptotic and never settle 
>>> down into playing. ESC and restart would usually fix this, but sometimes 
>>> the frontend would have to be killed.  Also, even when working well, 
>>> insertion of any popup artifact, eg press I, would cause stuttering. 
>>> This is with realtime priority, XvMC, use video timing. Without XvMC it 
>>> didn't work at all on these highdef signals. I don't think deinterlacing 
>>> was the issue, the problem seemed the same displaying to my monitor or 
>>> to the TV (at different times, always single-head). YMMV.
>> Did you ever try this with a separate graphics card rather than the
>> built-in graphics?
> Interesting suggestion. No I didn't, not having a PCI-E video card. I
> was starting to think about that possibility, though, realizing that the
> onboard graphics uses some of the system RAM for display (and therefore
> streams display content between the system RAM and the video chip at
> video-timing speeds). I am starting to wonder whether moving the video
> memory onto a card (and off the bus) might have a positive effect. 
To complete this thread ...

I took the plunge and bought the cheapest PCI-E card (based on NVidia
6200TC) I could find ($28 after rebate). CPU load has dropped 
significantly. I am now able to watch my highest-bandwidth HD stream on
the Athlon64 3200, using Standard driver and Kernel deinterlacing, with
roughly no prebuffering pauses. I do get the occasional pause when an
onscreen popup (eg. press I) is fading out. For a 17000 kb/s stream (eg
Survivor on HD), this is consuming about all of the CPU (4-8% idle,
using 'top -d 1').

I'm a little bummed about this, because I was quite keen to use the
on-mobo video. Something about an empty box as frontend was calling me.
Nonetheless, it works a lot better with the PCI-E video.

Just to warn the unwary, I still won't recommend the A8N-VM CSM mobo,
since the on-mobo sound is pretty crappy. (sounds like a 33-rpm phono
complete with cracks and pops). Unless you add a PCI soundcard too. So
much for single-board solutions, or this one anyway. Great feature list,
lousy execution.


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