[mythtv-users] Attractive cases and cheap DVD burners

[Joseph A. Caputo]

On Wednesday 16 November 2005 13:26, Raphael Pooser 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 "X Video".  I don't know everything it does, but the main thing 
that Myth uses it for is to scale video output to your display size.  
Without Xv, if you ran your Myth display at 800x600, but recorded your 
programs at some other resolution, then in order to display the video 
playback at full screen resolution the video would have to be scaled in 
software, which takes a lot of CPU.  Xv enables this to be done in 
hardware.

XvMC is "X Video Motion Compensation".  It is an extension to Xv that 
enables the video card to perform part or all of the MPEG-1/2 decoding.  
The level of support for this is heavily dependent on both the hardware 
and the driver.

HTH,

JAC