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16 SD video inputs

#1

Hi All

Does anyone have any experience with using many video inputs in vvvv?

I am researching to do a setup where the wish is at least 12, preferably 16 video inputs. It is for a performance that will use surveillance aesthetics so SD capture is fine. but we need long cable runs, so composite video is fine.

the solutions I have found so far offers up to 4 inputs on one board and then you are able to use 4 of those boards to get to 16 inputs.

So my questions are:

assuming an up to spec computer, are there any problems with that many video inputs in VVVV?

any other ideas? I am thinking actual surveillance systems, perhaps some of those systems combine multiple video streams on one screen and I could use texture transforms to get to them in VVVV.

thoughts and ideas are appreciated, just consider that we are on a budget, so it should not be too expensive either.

Sune

#2

Depending how deep the CCTV aesthetic goes, I’ve used quad multiplexers to put 4sd inputs into 1sd input, you could then use a quad input card. It was fine for my purposes!

#3

Using two of these cards http://www.datapath.co.uk/products/video-capture-cards/visionsd8 sounds less terrifying to me than 4 quad input cards.

The datapath drivers usually work perfect with vvvv and using more than one datapath card in one system never caused any problems to me.

Markus

#4

@sunep - pulling data from the cards into cpu ram won’t be the issue
the issue might be pushing all the pixels to the gpu (which has to happen in you main thread in dx9 so directly affects fps)

if you can live with lower resolution (e.g. 512px per tex) then you have no problems.
the limit is probably about 4096x4096px that you can push to the gpu per frame. so if your resolutions fit within that, then it’s just a case of having good nodes to produce the textures (i.e. perform all locking actions on other threads, bring double buffered image data into main thread to push into textures)

#5

@markus do you have an idea of the latency using the datapath cards?

#6

Latency of the DVI grabbercards made by Datapath is pretty short. I think it is as short as it can get using a standard WDM driver.
I never used the composite video cards from Datapath … so i can not really say anything qualified about their latency.

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