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Mac pro configuration and graphics cards

May 6, 2007 | 10:08 am

Hi,

for an upcoming project we will be projecting high-resolution video,
approx. 2048×407 pixels using two video projectors with edge blending:

http://local.wasp.uwa.edu.au/~pbourke/texture_colour/edgeblend/index.html

Most of the video processing will be slab/openGL based. We will be using
a Mac Pro, but are unsure about what configuration would be best
concerning graphical cards. We will need a total of three outputs, one
for the monitor controlling the Max patch, and two for the projectors.
We want seamless blending from the image of one projector to the other,
so we are concerned about processing for the two projections as well as
having synchronized updates of the two images for the two projectors.

We will obviously need two or three graphical cards, but what is
preferable: Processing images for both projectors on the same graphical
card, or having one dedicated graphical card for each of the two projectors?

Any advice appreciated.

Thanks,
Trond


May 6, 2007 | 12:51 pm

Dear Trond,

Having a dedicated card for each projector would be ideal, but there is a trade off. You would then be limited to two single wide cards such as the stock geforce 7300. You can give each card 8 lanes on the northbridge; but you are then limited to the 256 MB on the geforce. The Mac pro has just one double wide pcie slot for a highend card with 512 MB such as the quadro fx or radeon x1900xt. You can give this card 16 lanes, and it has 2 x dual link dvi. Would be nice to jam two of these into the mac pro if there was the space, but then you may also need a belkin i-turbine since each card consumes 120 watts of power.

In a similar setup I have used one ati radeon x1900xt to 2 projectors, and a geforce 7300 for maxland. There was little or no effect chain, and it seemed to perform fine. If you are running multiple shaders, you may consider a step up from the x1900xt, but fwiw it worked for me.

gr
Ryan


May 6, 2007 | 4:39 pm

interesting. i thought that it would be more efficient to not have a context
spanning two separate cards and instead use one card with two outputs.

On 5/6/07, Ryan wrote:
>
>
> Dear Trond,
>
> Having a dedicated card for each projector would be ideal, but there is a
> trade off. You would then be limited to two single wide cards such as the
> stock geforce 7300. You can give each card 8 lanes on the northbridge; but
> you are then limited to the 256 MB on the geforce. The Mac pro has just one
> double wide pcie slot for a highend card with 512 MB such as the quadro fx
> or radeon x1900xt. You can give this card 16 lanes, and it has 2 x dual
> link dvi. Would be nice to jam two of these into the mac pro if there was
> the space, but then you may also need a belkin i-turbine since each card
> consumes 120 watts of power.
>
> In a similar setup I have used one ati radeon x1900xt to 2 projectors, and
> a geforce 7300 for maxland. There was little or no effect chain, and it
> seemed to perform fine. If you are running multiple shaders, you may
> consider a step up from the x1900xt, but fwiw it worked for me.
>
> gr
> Ryan
>


May 6, 2007 | 11:05 pm

see Trond’s link. it is two sources blended after leaving cpu.


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