What Vision Mixer?

[dreddie]

Dear All,

 

I'm a researcher in surgical technology and hoping to mix stereo graphics with a stereo endoscope view that the surgeon has of the patient. This involves taking the output of two graphics cards and mixing them with the endoscope output (composite BNC or S-video).

 

Previously we have used two Panasonic WJ-MX50s for this purpose, but they are really too chunky to fit into the operating room. A while back I thought I saw something called an Edirol V400HD which looked ideal for around £1-2k. Can't find it at all now, though. Must have dreamt it.

 

The advantage of the Edirol seemed to be that it would mix RGB and video directly (rather than us using the video output of the graphics cards) and was a bit smaller.

 

It now seems there's only the Edirol V-4 (non RGB) or the V440HD which weighs in at £8-9k. In case there is any chance we could stretch to that budget, can anyone confirm that the V440HD will be able to mix two completely separate channels of RGB and video and provide two independent outputs?

 

Does anybody have advice as to what mixer we should go for? Compact size is important. I guess two V-4s would do it. It's vital to be able to fade in and out with chroma-key, by the way.

 

Apologies for the long post and thanks for any advice you can give,

 

Eddie.

[James]

Eddie,

 

Hi, - I'm just trying to understand what is going on here,

 

Did you own the WJ-MX50s that you used previously - if so do you have scan converters for the vga sources, if not then what resoloution are the vga sources.

 

If you do still have the WJ-MX50s then is it not possible to remote them and trigger them in the theatre via a push button switch into their GPI interfaces?

 

I'm suprised you don't have anyone video inclined at imperial in your department, I know there were a couple of video chaps working on stereo imaging in UCL who came from a video background who should be able to sort out your problems.

 

good luck.

 

James

[mac.calder]

Whilst it is true the 440 has two independant outputs, they are not two independant HD outputs. Think of it more as two mixers. To one mixer, you connect all your SD sources (Composite/SVideo) - and you have an HD mixer, to which you connect your computers.

 

The HD mixer also has a scaled up input taken from the output of the SD mixer. So output one can show any of the SD sources, and output two can show the output of output 1, or it can show any of the HD sources (Does that make sense?)

[dreddie]

Hi Guys.

 

Thanks for all the advice.

 

James - We don't have scan converters, but we have NVIDIA graphics cards with S-video out, so we were using that. We have a rack of computers and other kit that we wheel into theatres and the WJ-MX50s are quite chunky for that. The idea of having them somewhere else is a great one (and in fact we're just refurbishing so that might not be out of the question) but for the moment running cables elsewhere would be more of a hassle than carrying two WJ-MX50s around.

 

And of course we have video people here and I'll try to get hold of them too. Contacts at UCL also always welcome. If you could pass on the names that would be great.

 

Mac - I think I just about got what you said. Two independent outputs, but one of them is not HD. Is that about it? That doesn't matter too much. The video we are splicing graphics into is straight PAL. So if we can take two separate PAL video streams, splice in two separate lots of RGB graphics (using chroma keying), and have two independent PAL outputs then the 440 will do all we need. Like so:

 

PAL >-----
	  |------> PAL
RGB >-----

PAL >-----
	  |------> PAL
RGB >-----

Now does that make sense?

 

Since having RGB input is a bit of a luxury, I'm thinking of going for two V4s and using the S-video output from the graphics card.

 

What do you both reckon? Any other products I should consider?

 

Thanks again to both of you.

 

Eddie.

[gnomatron]

Given that your ouptut is PAL, RGB input is overkill, especially given how expensive it is. I'd say go for two V4s, quite small and you can link them via MIDI if need be, which will allow you to (I belive) use the controls on one to trigger the other. That or remote the MX50s as suggested.

[James]

Eddie,

 

If you already own the MX50s It doesn't seem to make sense to not use them.

 

Anyway - If you have a rack you wheel into and out of each theatre then I would have thought that having each of the MX50s on a tray or shelf in the rack would make sense. From a brief skim read of the manual the GPI in isn't configurable but serves to trigger the Auto Trans function. So if you can set the desks up so that Auto Trans operates key on / off then all you need is a little button (or a big one) sat across both GPIs so you don't need to have the MX50s out to operate the keying.

 

From what you say you need, if you are desperate to spend money then two V4s look like they would do what you want - SVideo would be fine if you are only ending up with pal anyway, Oh and If you want to get rid of them. let me know and I'll take the MX50s off your hands....

 

James

[Pete McCrea]

I'm sure I'd help James in taking and MX70 off your hands too if need be......

[dreddie]

Thanks a lot for the info everybody.

 

The MX50s were borrowed and one has already gone back.

 

I'll ask if they need a home for the other one but don't hold your

breath...

 

Thanks again,

 

Eddie.

[peternewman]

Rather busy, so not a particularly helpful reply, but may provide some additional Googling. You can get some cards that fit into a PCI slot (they only use the PCI bus for power), they will chroma key a signal (VGA I think) over a composite input, providing a composite output. From my testing through a matrix this signal seems to be in sync with the input (I imagine with a frame or two's delay) so you could route the clean and overlayed versions through a matrix and switch between them, or if you do actually need to fade, rather than just switch, then you could get two cheaper vision mixers, such as the cheapest Edirols. I'm not sure how much these cards cost, but I imagine they're less than a pair of V4s. Anyway hopefully this makes sense, I can probably find out the manufacturer of these cards, although it may take a few days, if any of my explanation doesn't make sense then someone else can probably explain it (unfortunately I'm offline for the next couple of days).