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Scan converter underscan issues

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Mike Browning
Scan converter underscan issues
on Oct 26, 2011 at 6:50:21 pm

Background:
We use two computers for CG inputs on our switchers. One feeds full screen graphics and the other feeds an external key/fill. We're still on SD technology. We're using Extron VSC-500 scan converters to get these VGA signals to the switcher.

The Issue:
We started recording our programs to a PC for web streaming, and discovered we're dealing with underscan issue for all graphics. Because we'd only worked on broadcast monitors, not computer displays, we never had to deal with this. There are no 'overscan' options on these converters, and even at 100% scaling, our full screen graphics show up with black margins. The other downside is for keyed graphics, we get ugly borders at the edges of the entire frame - so everytime a lower third comes up, for instance, there are black lines on the action safe margins of the camera feed. In addition, when re-editing graphics back in, we noticed stretching in our images (which should be the same aspect ratio to start with). I contact Extron about this a couple times and they haven't responded.

The Question:
I'm looking for an inexpensive scan converter that doesn't have black margins, allows me to turn underscanning off, and doesn't stretch the image one way or the other. We want to be able to record and stream video directly from the switcher without having to re-edit in graphics.

Thanks for your time and suggestions!

Mike Browning


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Bob Zelin
Re: Scan converter underscan issues
on Oct 27, 2011 at 2:18:00 am

The Question:
I'm looking for an inexpensive scan converter


REPLY - you just said it all, my friend. There are countless WONDERFUL scan converters that will do anything you want.
But you want inexpensive, but with all the expensive features.

Sorry, Blackkmagic doesn't make a scan converter yet. But if you have money, Ensemble, Folsom, Communications Specialties all make teriffic products.

Bob Zelin



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Andrew Rendell
Re: Scan converter underscan issues
on Oct 27, 2011 at 10:26:37 am

Um, I don't wish to appear pedantic, but you want to take an image at a size that gives you black borders with a given screen size and make it fill that screen size without black borders without stretching the image. Do you want to have a think about what you're asking????

BTW black lines at the edges when you bring on a key (even if it's outside the safe areas) is seriously unprofessional IMO - I'd have whoever supplied it resupply with it done properly (or pay for it to be fixed).


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Mike Browning
Re: Scan converter underscan issues
on Oct 27, 2011 at 2:58:49 pm

Thanks for the quick - albeit abrasive - replies. Didn't really answer my question though.

1) Bob - Inexpensive is often relative. I'm certainly not looking for top of the line (whose budget really allows for top-of-the-line every time?), but do you have a specific model or two in mind? It has been difficult to find such things as 'underscan on/off' in product descriptions. And I am certainly not on my up-and-up about broadcast equipment (I am by no means an engineer). This is why I turn to other pros like yourself.

2) Andrew - not to be smart - but I'm talking about 640x480 graphics... filling the same size screen. The black bars are coming from 'underscanning' in which the converter scales the source down. What happens with the stretching is the converter is literally stretching the image out of proportion, for whatever reason. Really makes no sense, but there's no way to 'lock' proportions on this Extron. Also, again, the lines on the edge of keyed frames are coming from the scan converter. Everything coming from our CG sources are clean, professional graphics that key well elsewhere.

Thanks for your responses, seriously, although I'd appreciate a bit more specifics in terms of product recommendations - surely y'all have had a good experience with specific models?

Thanks

Mike Browning


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Andrew Rendell
Re: Scan converter underscan issues
on Oct 27, 2011 at 4:38:08 pm

Sorry. Setting up that side of things isn't really my field (I've been the guy who has to fix things in the edit suite too often, for which I now charge A LOT to do, hence the attitude).

Google seems to find a lot of stuff, until you start looking for the gen lock connectors, when suddenly there doesn't seem to be that much around (since doing that kind of work needs gen lock, I'm using that as a proxy for what you need).

Good luck.


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Mark Suszko
Re: Scan converter underscan issues
on Nov 2, 2011 at 8:29:21 pm

I'm a huge fan of Communications Specialties' scan converters, and they can do what you want, but may not fit your budget.

Maybe another perspective here - I will point out the obvious, that you're busy fixing an analog SD switcher problem in 2011, and it may be simpler and cheaper in the long run to get a new switcher that can automatically deal with these things. Your scan converter problems becomes part of the justification for the upgrade, and a legit reason it is.

I know that doesn't solve your problem *today*. But your situation is what a lot of used car owners face, when the mechanic starts listing the parts and labor charges to make the old daily driver road-ready for another year. At some point you're throwing good money after bad. Switchers today are crazy cheap for the features they offer, and the market is depressed, prices are DOWN. It may well be that the new switcher is cheaper and more capable with handling these computer graphic inputs, than the cost of two medium to high-end scan converters to patch into "old Faithful".

Our Scan-Do cost $6k brand new, some years ago now. It would fix your black edges problem for one input, but even if they are only three grand apiece now, I bet you could get a switcher that doesn't even NEED scan converters for less than the price of two of these scan converters. And you'd have a NEW switcher, probably with other cool abilities you don't have now, more built-in DVE's and keyers, for example, and more programmable effects.

Do some number-crunching, and maybe it works out better to go new than hack around the problems of the old.


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