Forums > Jitter

Using GPU vs. CPU


Dan
March 30, 2008 | 11:46 am

Long story short: I have 6 live feeds, and various movie files that get displayed on to 9 screens. As you can imagine, my computer does not like this. I read up on jit.gl.slab tutorial, and this helps speed things up quite a bit.

My question(s): I have 3 Video cards (2 Visiontek 2600XT quad, 1 Visiontek 2600 dual).

When I use any jit.gl.xxx patch does it use a specific card video card to do the processing? Can I assign which card it goes to?

I am using jit.dx.grab to input the live feeds (FireWire DV Cameras). Can I grab the video with the GPU directly?

Thanks,
Dan


March 30, 2008 | 3:09 pm

Hey Dan

just a note about the cameras –
you mentioned in a post just prior to this that you are using "Creative webcam" cameras – but here you say you are using firewire dv cameras –
all of the Creative webcams I could find on their site are usb…

anyway – not at all trying to be picky BUT on a mac using quicktime you can only grab from one firewire dv camera at a time –
you can use multiple IIDC firewire web cameras – for example the unibrain cameras

As far as I understand it you can not grab directly to the GPU as there is no link – the usb and firewire buses connect to the CPU and thus the signal has to go through that point.

another option is to use the 1394 imaging converter boxes –

http://www.theimagingsource.com/en/products/converters/

you can use up to 3 of these on a current mac firewire bus, and with 3 ports per unit (switchable in max) that gives you 9 possible cameras total (though only 3 at a given time)

I understand that USB 2 is often almost as fast as firewire 400 on PCs and I wonder about USB bandwidth limitations but hypothetically you could use a mix of USB and firewire converter boxes…

anyway – they work very, very well and are considerably faster than any other inputs I have used – but they are not cheap!

you might also consider working in 4:1:1 color space instead of 4:2:2 to save a little overhead…

best of luck

jamie

—– Original Message —-
From: Dan Sent: Sunday, March 30, 2008 7:46:05 AM
Subject: [jitter] Using GPU vs. CPU

Long story short: I have 6 live feeds, and various movie files that get displayed on to 9 screens. As you can imagine, my computer does not like this. I read up on jit.gl.slab tutorial, and this helps speed things up quite a bit.

My question(s): I have 3 Video cards (2 Visiontek 2600XT quad, 1 Visiontek 2600 dual).

When I use any jit.gl.xxx patch does it use a specific card video card to do the processing? Can I assign which card it goes to?

I am using jit.dx.grab to input the live feeds (FireWire DV Cameras). Can I grab the video with the GPU directly?

Thanks,
Dan



Dan
March 30, 2008 | 8:29 pm

Jamie,

Thanks for the reply. I was trying the Creative Webcam first with conflicts. The webcams I have now are from Encore Electronics. Super cheap and work like a charm. However the quality is better from the Firewire mini-DV cameras ($149 each). I haven’t had any problems grabbing them (I have 4 hooked up). I am also using a Canopus PCI Capture card with an s-video input and another Canopus external device.

I will try the change in colorspace.

Thanks,
Dan


March 31, 2008 | 10:50 am

Jamie
I don’t want to be picky BUT , one is talking about PC and another about Mac. Just to make it clear for other readers.


March 31, 2008 | 2:21 pm

Yes! Right!

I thought I had specified this but I see I did not – sorry for the oversight

My experience is in developing for Macs and I intended to say that things might be different on a PC

this is what I was trying to allude to when I mentioned the USB option on PCs being quite fast

so sorry for any confusing vagueness

best!

jamie

—– Original Message —-
From: jasmin
Sent: Monday, March 31, 2008 6:50:40 AM
Subject: [jitter] Re: Using GPU vs. CPU

Jamie
I don’t want to be picky BUT , one is talking about PC and another about Mac. Just to make it clear for other readers.

jaz


Viewing 5 posts - 1 through 5 (of 5 total)