[mythtv-users] What correct video model as ouput of MythTV

Michael T. Dean mtdean at thirdcontact.com
Tue Jan 10 18:29:23 UTC 2006


YanJun Lu wrote:

> Has anybody tell me what difference among output of video in Linux
> ,Especially for MythTV, Because I do not know how to select correct
> type of video as output of Mythtv, for instance , There are many video
> of output as below: Directfb/Null/XV/XvMC/SDL/and so on.

DirectFB is for people who are not running X Windows (but you have to
have Myth compiled specially for DirectFB).

Xv is the X Windows X video extension and is typically what you want to
use. It provides support for the video card's hardware YUV routines, for
brightness/contrast/hue adjustments, and hardware accelerated scaling
(all of which are ideal for video).

XvMC is the X Windows X video Motion Compensation extension which
provides support for GPU-assisted inverse Discrete Cosine Transform
(iDCT) and/or Motion Compensation (MC) (two processor-intensive parts of
MPEG-2 decoding). This hardware acceleration of MPEG-2 decoding is good
for high-definition MPEG-2 video on systems whose CPU's are strained by
software decoding, but only works with GPU's whose drivers support XvMC
(currently, I think that means NVIDIA and some Via and possibly some
Intel graphics cards).

SDL is the Simple DirectMedia Layer, which provides a unified interface
to "any" video/audio driver (whether X-based or not), and typically
within X is just another way of getting to the Xv extension.

So, start with Xv and if you need acceleration and have a supported
video card, use XvMC.

Mike


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