[mythtv-users] Attractive cases and cheap DVD burners

[Jesse Guardiani]

Raphael Pooser wrote:
> Michael T. Dean wrote:

[...]

> Have to ask because I have never been able to figure out what the 
> difference is: What is the difference between xv and xvmc.  I read 
> somewhere that xvmc is a hardware thing while xv is jsut somekind of 
> software extension.  But if that were true, than why is xv dependant 
> on the graphics card driver at all?  The ati cards can use xv, but not 
> xvmc, why is that, and is there a giant performance difference between 
> the two?  I read on this list a guy using xvmc with an nvidia card 
> taking 2-3% proc time in X to run a 720x480 stream, which is exactly 
> how much is takes using xv with an ati card?  Would it take even more 
> using xv and not xvmc?  Sorry for the seemingly obvious to answer 
> question.  My friend is getting ready to builf a myth box using nvidia 
> and as I use ATI I want to make sure I have enough knowledge to help.


XV is efficient software decoding.
XVMC is hardware assisted software decoding.

On my nvidia 5200 + Celeron D @ 2.93ghz + 1Gb DDR 3200 RAM, normal mpeg2 
playback takes about 13-15% CPU using XV.
Using XVMC, it takes between 8-10% CPU. So no, it's not a dramatic 
difference unless you're using a low power CPU like a 733mhz
P3.

I don't even bother with XVMC for three reasons:
1.) The OSD is GRAYSCALE for some reason. (is this fixed in SVN yet?)
2.) FF, Rew, Next, and Prev cause about 5-10 seconds of jitter and 
skipping when using XVMC.
3.) Even without any sort of de-interlacing turned on, I get really bad 
flicker on the OSD.
     For example, when I change the volume the OSD volume bar is 
unintelligible it flickers so much.

Also, note that it really is just hardware assist. It's nothing like the 
PVR 350's hardware playback.
With the 350, I could max out my CPU and compile code in the background 
while watching a show
without any skipping, jitter, etc. With the nvidia card it doesn't 
matter if I use XV or XVMC, I always
get some skipping and jitter while compiling code in the background or 
burning a DVD. (would a real
P4 with HT enabled solve this?)

If the jitter, flicker, and grayscale problems could all be eliminated 
then XVMC would kick-a**, but
as-is it seems rather pointless on my hardware.

-- 
Jesse Guardiani
Programmer/Sys Admin
jesse at wingnet.net