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

[Mark Knecht]

On Tue, Mar 23, 2010 at 6:26 PM, Raymond Wagner <raymond at wagnerrp.com> wrote:
> 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.

I've done this for years, really since we started using Myth, and not
had any problems other than my winfe once in awhile forgetting and
shutting the machine off. I'm not overly worried about this.

I'm not following the multiple interfaces part unless you are talking
about the BluRay/TV part of the outline in which case I understand.

>
>> 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.

Yeah, that's what I thought. I expect it will come along over time so
if I'm building the Media PC I figured I might as well get positioned
to play with it.

>
>> 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.

Wonderful! Good to know.

>
>> 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.

Sorry. Yes, the i7-920 is a 4 core chip but each core is hyperthreaded
so it appears to be 8 cores. I also have a i5 661 here that is dual
core hyperthreaded and Gentoo works very nicely compiling jobs as if
it was 4 cores. I'm purchasing an i7-980x which is 6 core
hyperthreaded looking like 12. There aren't any Intel 8 core devices
as you correctly state.

>
>> 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).


OK then I'm goign to have to study the docs a bit more on this
account. I thought I was seeing features that were very different.
Probably I'm just mistaken.

thanks very much,
Mark