[mythtv-users] Trouble with HD playback

[Anthony Vito]

> However I beg to disagree with Vito
> about the price performance of moving to 400FSB.  According to this
> benchmark you get less than 4% encoding improvement for 21% (196USD vs
> 155USD) more money.
> 
> That much performance difference isn't worth the money.  The sweet spot
> is still at XP3000.
> 
> http://www.tomshardware.com/cpu/20030623/p4_3200-10.html

There is a big problem with that benchmark... We aren't encoding Mp3's
here which uses nearly no memory bandwidth... 1200kbps in --> CPU -->
128kbps out.. is hardly taxing on a DDR333 memory system capable of
~21.6Gbps.... However HDTV decoding.... 20Mbps in --> CPU --> 1.5Gbps
out... is at least a measurable fraction of the (theoretical) memory
bandwidth. Couple that with the actual algorithms at play... mpeg2
video requires huge amounts of reference data to decode each frame
properly. At HDTV resolutions this data does not fit into L2 cache,
and thus the memory subsystem's speed and latentcy become very very
important. This paper here
http://www.cs.princeton.edu/~chenhan/papers/icme2002t.pdf deals with
some of the issues on optimizing HDTV software decoding, specifically
how to utilize the memory subsystem efficiently.

All papers, numbers, and theory aside.... The simple fact is that
every last little bit of performance helps when you're putting
together and HDTV system. My experiences and what I've read here
indicate there is a lot more to do with hardware "playing nice" they
actual performance numbers.(people with FX53's getting jittery
playback) If you can come up with an XP3000x266/board/video/ram combo
that can play back HDTV as smooth as my bottle of vodka, we would
would all benefit from it. I have an overclocked 2800MP(<100USD) chip
doing it, using onboard video ( which makes the FSB even more
important for my setup )... So a proverbial "Show me the hardware!" is
left to you.

-- 
Anthony Vito
anthony.vito at gmail.com

Biostar M7NCG 400
Mobile XP 2800 @ 2.2Ghz ( 12x183 )
512M DDR Mushkin
pcHDTV 2000
Using Onboard GFMX for Xv
Infocus X1 (800x600 @ 100")