Video grabber

On a sunny day (Tue, 9 Feb 2010 10:57:34 -0000) it happened "Grumps" wrote in :

Why make a VGA video grabber? In case of a PC grab the display buffer, in case of an FPGA the same. If all else fails but a HD Canon camera and point it at the screen.

Thanks. All very good suggestions, but none are acceptable in this situation. It HAS to be from the VGA analog signal.

On a sunny day (Tue, 9 Feb 2010 13:55:13 -0000) it happened "Grumps" wrote in :

Anna Log has been dead for a few years :-)

RIP poor Anna! However, there are many users of Anna's VGA. And some of these want to frame grab high res. I can buy a grabber for $2k. But that's not a proposal I'd want to put to my customer.

On a sunny day (Tue, 9 Feb 2010 14:12:48 -0000) it happened "Grumps" wrote in :

One thing you may consider, is if it is not a moving, but a static screen. If it is static, you could just sample over a line, slowly moving from line to line, and rebuild the frame in memory. That only needs simple H and V sync, and a variabel delay counter, fast sampling gate, and cheap ADC.

I wish life were that simple. It's a moving image that we have to compress. The compression is ok. Grabbing the image is currently the part that's giving me a headache!

Look at the chips they use as front-ends on LCD monitors.

Just buy the 2k$ box. Assuming you're a consultant (you talk about your customer), and you charge what we charge, 150$/hr, the 2k$ box represents 13 billable hours. Can you design a complete solution with gerbers and files ready to go to manufacturing in less than two working days? With firmware and PC front end?

Unlikely, even you're as good as me. :) So, either you don't charge enough, or your customer or you are in over their head.

You also talk about "monolithic decoders", which to me sound like composite video-to-digital chips. All the hard work is already done in the IC. It's not a great achievement to get those working.

OTOH. what you are talking about is far from trivial. Good luck to you if you think it is.

There are video capture cards...

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Good idea. I often wondered how they converted the signal.

Otherwise, just buy the off the shelf box.

We have to deliver several hundred of these, and a price of $2k + the rest of the system is WAY too much.

No problem with the monolithic decoders. We've used them before and they work well. But are limited to 170MHz (as far as I've found).

I've looked at many but have not found any (except expensive $2k units) that will digitise a 250MHz VGA signal.

That's an idea I've already had too. All of the monitors we have here are only 1920x1200@60Hz which is about 150MHz pixel rate. I'm going to have to get another monitor in and take it apart.

On a sunny day (Tue, 9 Feb 2010 16:44:15 -0800 (PST)) it happened snipped-for-privacy@netzero.com wrote in :

Right, that is the correct way to think about it. My old boss would say: 'I want to see the whole project,' and then have me design a whole new system that does not need the VGA to mpeg2 or whatever.

But these days I would buy a 150$ LCD monitor, a 600$ Canon HV20 HD camera, have wooden box made for 100$, charge the customer the 2k$, and have 1150$ profit for coffee, hehe :-)

I'm glad you put the smiley at the end. It would be my customer who had the "hehe" right in my face if I proposed that solution.

If you can live with a low frame rate then one of the cheaper VGA2USB cards might do the job eg.

Can't you specify another VGA card that has a digital output?

It seems to me like utter madness to redigitise a fast analogue video stream that is originating from a computer.

Regards, Martin Brown

It'd have to be the VGA2USB-pro. Actually, even that has an issue. Epihpan do have a real 2k x 2k unit for $8k.

That was my first hope, but they say a categoric "no". We can capture DVI at this resolution ok. Tried and tested.

Well, if our end price is more than the cost of replacing VGA cards, then maybe they'll think again. But as it stands, it is a very arduous route for them to take to change hardware/drivers etc.

On a sunny day (Wed, 10 Feb 2010 11:13:43 -0000) it happened "Grumps" wrote in :

Your customer is an idiot anyways if he does want to digitise VGA, so who cares. And he would not know the difference!

Thanks. I'll forward your reply to him :)