[mythtv-users] XF4.3.0 too slow for HDTV? (was BadAlloc)
brad+myth at templetons.com
Sun Dec 5 20:36:09 UTC 2004
I am also having a nightmare with this. My efforts with a Radeon board
were unproductive on an Athlon 3000. Choppy video, reversed colour,
a bright purple bar on the right side of the screen. Radeon 9200se.
NVidia has been a nightmare as well though. The drivers are flaky.
The latest 6629 driver crashes the latest Xorg and 2.6.9 kernel.
xmvc worked on a 2.4 kernel but has not yet worked on 2.6.9 for me.
Sometimes I get the blue xvideo of doom, where all xvideo screens are
just a blank bright blue. Sometimes you can get rid of it by removing the
nvidia driver from the kernel, and re-inserting. Sometimes a hard boot
is needed. Yikes!
When it is working, with xvideo, I show about 10 to 20% idle playing HDTV,
which is not enough of a cushion, but it works if the system is quiet.
With xvmc (in mplayer) it's much better, about 60% idle. However, I
have not managed to get xvmc to work with myth. The rpms don't have it
compiled in and my efforts to compile myth have failed due to some bizarre
library problem I am having (probably due to the fact I upgraded RH9 to
However, the reports from people I have read about xvmc in Myth suggest it
is not ready yet, so I have not tried too hard.
Better has been a Pentium 4-3ghz. Reports are that P4s blow away Athlons
at mpeg tasks. The benchmarks are quite clear on encoding, I have not seen
benchmarks on decoding, but my own tests show about 40% idle time, if I
recall correctly, on the P4-3ghz than on the Athlon-3000.
Why? Well, as you may or may not know, the Athlon-3000 runs at just 2.2ghz.
AMD's processors normally are faster on typical applications, so AMD started
putting the number on them to say "As fast as a Pentium at 3ghz". And
largely they are right -- in fact at many tasks they are faster than the
Intel at 3ghz. Athlon-64s are even faster, and so the A64-3000 is just
a 2ghz chip!
However, when you have particular algorithms that have a series of
steps with predictable branches, like mpeg, raw ghz is what makes the
difference. So if buying a processor just for myth, consider Intel again.
The downside of Intel is that because it is really running at that
clock, it runs hotter. So AMD is a better buy for most applications,
but not mpeg.
So only the nvidia is fast enough even in xvideo mode but alas, I can't
get it to drive my HDTV at 1080i or 540p. I get a "double vision" problem
that looks like an interlace offset error. I don't get it from the
Radeon, nor from the NVidia under powerstrip. But I remain hosed so
I may be forced to take the nasty step of returning my HDTV.
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