[mythtv-users] please explain XvMC

[Chris Wieringa]

>>I have a Dual VGA setup with a recent NVIDIA card, and an analog bttv capture
card.
>>
>>What are the benefits, if any, of compiling Myth with XvMC support enabled?
I think I have only seen references to people using 
>hardware encoder cards.

For you, there would be none.  See below.

>XvMC accelerates some of the MPEG2 decoding in your video cards 
>hardware.  The advantage is that it takes less CPU power to do the 
>decoding.  The big disadvantage is that you can't use any filters (like 
>deinterlacing) with it.

Yep, X video Motion Compensation is a feature that can be enabled on some
cards (Nvidia mainly, but some ATI cards have support for it AFAIK) to do MPEG2
decoding.  Usually this is used with playing DVDs, however, the Hauppauge
PVR-x50 cards capture streams in MPEG2.  Therefore, decoding of these streams
are done on the video card with little impact on the CPU.  If you are using a
an analog bttv capture card, you will not be capturing your streams in MPEG2,
so there is no point in compiling in XvMC.

Chris Wieringa
cwieri39 at calvin.edu