FPGA VGA output deinterlacing/remove flickering

[MIRKOSOFT]

Hi!

I bought FPGA with VGA output.
VGA works with many resolutions - from 640×400 up to 1920×1200 and many resoluions are non-standard, even in composite/SVHS format 720x480/576.
FPGA can run many computers, I prefer 8 or 16-bit systems and interlaced modes of these systems are near all flickering.
I own also real retrocomputers, for example Commodore 128 with composite and RGBI (CGA) output - this CGA output is scaled and deinterlaced (removed flickering) by device recommended on this forum.

Now FPGA is variable - resolutions are different and in many times not universal, only one machine requires written 1920×1200 which is working correctly except one mode inside the system - mode of old Commodore 64 which has interlaced modes flickering.

So - I need simple deintelace/remove flickering device with VGA input and VGA output - no scaling no other functions - only support up to 1920×1200 (if is not available with this resolution request I can reroute output). Maybe its non standard mode will require Multisync.

Can anybody help me with selection of proper device or recommend me any?

If anybody knows also about device removing flickering from composite/SVHS input and VGA output, please reply too.

Many thanks.
Miro

[pandy]

No clue how it is possible to have flickering in progressive VGA but best way to solve problem is to add anti-flutter filter to your FPGA design.

[MIRKOSOFT]

How is possible to have flickering CV converted to VGA then?
I must to use software deflicker but not success...

Miro

[jagabo]

The FPGA is probably converting interlaced analog SD output from the computer emulator one field at a time with a simple bob deinterlace, hence the flickering. I don't think there's any such VGA deflickering device. You might be able to put together a series of devices like a VGA to component converter, a component scan doubler, and a component to VGA converter. But that's likely to work only a specific resolutions and refresh rates. And it won't be cheap. Maybe you can find an old LCD monitor with VGA input and a long response time.

[MIRKOSOFT]

Ok, what means long response time - approx. value?
Miro

[jagabo]

You're probably looking for 30 to 40 ms (1/30 to 1/25 second). Finding specs that indicate that will be hard though. There's always a lot of fudging of the numbers because response times vary depending on the the difference between the last color/brightness and the new/color brightness. A manufacturer will look for whatever transition is fastest and report that as the response time. Not the average of all transitions, or of full black to full white, or whatever.

[pandy]

Antiflutter filter is pretty straightforward (line buffer and vertical average with current line) and can be added to FPGA but i assume flutter is introduced by your display not FPGA board (i assume board not doing deinterlacing with bob method - this is common issue - progressive source, sent as interlaced so bob deinterlacing performed in display to convert it to progressive).