[mythtv-users] Does 3d performance matter at all with Myth?

Raymond Wagner raymond at wagnerrp.com
Wed Mar 24 01:26:06 UTC 2010

On 3/23/2010 21:00, Mark Knecht wrote:
> 1) My wife's desktop
> 2) Myth backend
> 3) RAID backups for other machines on the network.
> and...
> 4) Only slightly possible is driving a large screen TV

It is generally not suggested to run a backend on a machine primarily 
used as a desktop, as the user could be interactively doing things that 
may compromise the stability of the machine, or at least cause 
sufficient IO load to cause data loss in a recording.  Also, running 
multiple independent interfaces can be difficult, and generally requires 
having two separate graphics cards, one for each independent X server.

> Additionally I'm going to stick a BluRay drive in it just in case I
> ever manage to get it near the TV in #4.

There is currently only very limited BR decryption capacity in Linux (or 
open source in general), and no playback libraries that can handle the 
disk layout.

> With that usage model how much does the VGA's 3d performance matter?
> Does 3d performance have any effect on how well Myth runs?

MythTV does not currently use any 3D, and only uses OpenGL for UI 
compositing.  Just about any currently available hardware OpenGL 
implementation should meet its foreseeable needs.

> Due to where the processor price points are this machine will be
> pretty powerful as it will run an i7 920 8 core processor.

The i7 920 is a quad-core processor.  Intel does not currently 
manufacture an octo-core processor.

> However if the
> only way to get to something like VDAPU is through some link to 3d
> then I'd better pay attention to that.

VDPAU has nothing to do with anything 3D.  While decoded frame can be 
offloaded to OpenGL textures for compositing, the current implementation 
in MythTV uses VDPAU's own dedicated compositing methods.  VDPAU uses 
the shader hardware for running its deinterlacers, which requires a 9500 
or GT220 to run the most demanding filter at 1080i.

> As this machine is in a Media PC case and I'm going for very, very
> silent most VGAs without fans have lower 3d performance.

See above about the deinterlacers.

> Related question, is anyone using the nvidia Quadro processors as
> opposed to the more standard desktop GeForce series? There are some
> very nice Quadro cards without fans.

The Quadro cards are nothing more than their GeForce counterparts, with 
some additional APIs exposed to accelerate certain tasks in some 
professional applications (usually CAD/CAM software).

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