MiST VGA Compatibility

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Re: MiST VGA Compatibility

Postby Newsdee » Sun May 15, 2016 12:54 pm

The NES core worked with all displays I've tried, should give a solid 60hz.

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Re: MiST VGA Compatibility

Postby seastalker » Sun May 15, 2016 3:52 pm

I am really looking at getting a MIST. I thought to offer an alternative to the XRGB-Mini for those asking about upscalers. Panlong makes them and I have a SCART to HDMI one of theirs on the way. I plan to test it with my 800xl and it's scart cable. Anyone else try this Panlong with the MIST? It's a lot less money than the XRGB-Mini and there are comparison videos and reviews on Youtube that convinced me to try one.

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Re: MiST VGA Compatibility

Postby Newsdee » Mon May 16, 2016 2:32 am

I've used cheaper VGA->HDMI boxes and the Gonbes 8200/8220 arcade board. Both give cheaper alternatives to the XRGB but come with caveats.

I'd be curious to know if this Panlong can handle 50hz signals... that's the usual problem with cheaper upscalers.

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Re: MiST VGA Compatibility

Postby Newsdee » Mon May 16, 2016 11:18 am

I've got a new HDMI converter today to try because it claimed to support 50hz. It kind of does, but I realized it isn't an upscaler, just some kind of "HDMI compatibility box". It should help get a better signal but only if the TV supports 50hz via HDMI (an older TV of mine didn't, but replaced it now with one that does).

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Re: MiST VGA Compatibility

Postby seastalker » Mon May 16, 2016 3:14 pm

This is the video that inspired me to look into it:

Gamerade - Best Video Quality With Old Game Consoles - SCART to HDMI - Adam Koralik
https://www.youtube.com/watch?v=RS55pmLIEjA

Admittedly, it may not be my best 800xl option (I bought it mainly for consoles and a future MIST), but if it doesn't hamper the XL from hz signal incompatibility, at least it will connect it to a tv through HDMI and otherwise be better video than RF. I have to wait before it comes in but will return with results of the Panlong.

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Re: MiST VGA Compatibility

Postby ericgus » Wed May 18, 2016 7:26 am

Newsdee wrote:I've got a new HDMI converter today to try because it claimed to support 50hz. It kind of does, but I realized it isn't an upscaler, just some kind of "HDMI compatibility box". It should help get a better signal but only if the TV supports 50hz via HDMI (an older TV of mine didn't, but replaced it now with one that does).


Which one did you get just out of curiosity ?

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Re: MiST VGA Compatibility

Postby Newsdee » Wed May 18, 2016 11:41 am

ericgus wrote:Which one did you get just out of curiosity ?


This one: http://www.port-ta.com/products/27.html

Tried it with a Dreamcast yesterday and it worked great too :D It doesn't upscale though nor converts the frequency (ie 50hz remain 50hz)

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Re: MiST VGA Compatibility

Postby Newsdee » Thu May 19, 2016 12:43 am

I've opened the box... and it turns out the chip inside is exactly the same as my other HDMI converters (Macro Silicon MS9282). lol...

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Re: MiST VGA Compatibility

Postby ericgus » Sun May 22, 2016 5:41 am

Thanks for the info!

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Re: MiST VGA Compatibility

Postby DrOG » Wed Aug 24, 2016 5:58 am

Hi all!

Last week I acquired a Philips 20HF5474 Hotel TV, and now I share my experiences!

Since I don't have a MiST (yet), I tested it with original c64 hardware, using RF, composite, S-video and my Turbo Chameleon 64's VGA output, and the minimig core http://retroramblings.net/?page_id=276 using PAL mode and direct VGA <-> VGA2SCART connectors. The TV works flawless in all above mentioned modes, but you need to use a cheap, passive adapter to convert it's DVI input to VGA. This is good enought for the purpose: http://www.merkador.hu/spd/MK3S3O1P20/D ... er-245-pin

Other, less VGA-incompatible cores (Atari2600, Atari800XL, VIC20, ZX-One, FPGAPCE, OCMSX) work too.

About the TV: http://www.p4c.philips.com/cgi-bin/dcbi ... 26slg%3Den

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Re: MiST VGA Compatibility

Postby DrOG » Wed Aug 24, 2016 5:59 am

Double post, please delete this!

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Re: MiST VGA Compatibility

Postby Sorgelig » Wed Aug 24, 2016 6:44 am

I've got OSSC. Originally i've though it would be a best video converter for all cores.... But alas...
1) OSSC doesn't have memory chip. So, it cannot do frame rate conversion.
2) Again, because of lack of memory, some video modes (like 320 lines @48Hz) won't work on many TVs
3) It doesn't mix audio into HDMI. (even cheapest VGA-HDMI converters can do this!) So, forget about convenient connection. Sometimes it's even impossible to feed the audio by other way than inside HDMI.

My big hopes crashed very bad. Expensive converter is actually trash. It's open source but very little you can do...

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Re: MiST VGA Compatibility

Postby Newsdee » Wed Aug 24, 2016 7:16 am

Oh man that sucks... maybe it can be coupled with a device to mix video and audio into HDMI, but that's one more box to the chain.

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Re: MiST VGA Compatibility

Postby Doozer » Wed Aug 24, 2016 7:27 am

Newsdee wrote:Oh man that sucks... maybe it can be coupled with a device to mix video and audio into HDMI, but that's one more box to the chain.


Despite the advantage of HDMI technology, the digital signal processing time (sampling, frame reconstruction, timing alignment) is behaving badly with old school RCA/SCART analogue signal. I am also looking for a solution to use modern screen but not at the price of the latency.

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Re: MiST VGA Compatibility

Postby Newsdee » Wed Aug 24, 2016 11:38 am

The XRGB Mini does framerate conversion... but it comes at a very steep price and a little latency (24ms or 1.5 frames apparently).

Mine takes everything I throw at it though. I need to take some time to sort out nice profiles for each system/core though.

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Re: MiST VGA Compatibility

Postby Doozer » Wed Aug 24, 2016 12:20 pm

The XRGB mini is effectively not bad at performing the conversion. Only two modes are usable on the device to avoid the low-pass filtering and they do not do scanline when used. The 'NATURAL' and 'PICTURE' modes can deal with the progressive and interlaced content. Best case input lag is measured at 20ms. On some device (like the DVDO Edge) the input lag is measured to be as low as 6ms.

Had someone experiences with the DVDO Iscan mini? (I know that modes like 480i and 576i are not detected/upscaled by the device)

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Re: MiST VGA Compatibility

Postby Newsdee » Fri Aug 26, 2016 10:26 pm

I just got a crazy idea... could the Zx-Uno be repurposed. into an upscaler? It has GPIO directly connected to the FPGA and uses SRAM which I believe to be low latency?

http://zxuno.speccy.org/maquina_e.shtml

It's also open source and was being sold at aound 70 Euros.

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Re: MiST VGA Compatibility

Postby skeezix » Sat Aug 27, 2016 2:12 am

I keep wondering if it would be worth it to make a 'VGA signal cleaner'; a general purpose upscaler has a lot to do .. some of them handle audio splitting or merging, and certainly have to handle a varied set of resolutions (often unclean), from NTSC and PAL, etc.

But I've found a few upscalers barely do the job (like gbs-8220), which often themselves spit out goofy signals (not centered, or clipped, or wrapping, or etc); machines like the MiST can emit a VGA signal, but often not quite right.

So, it is tempting to make a little FPGA or super fast CPU that can receive a VGA signal, produce a frame image, and spit out a VGA signal of the last complete frame (or something along those lines.) You'd lose half a frame or a frame to latency, but could allow for an image that can be stretched or centered or otherwise tweaked. .. just add some flexibility to a dumber signal generator that doesn't want to have those options, for whatever reason.

Not sure it would be economical for the number of people who might want such a thing.. dunno :)

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Re: MiST VGA Compatibility

Postby Newsdee » Sat Aug 27, 2016 3:02 am

That FPGA exists and it's called the XRGB-Mini Framemeister :) The problem is precisely how to build it cheap.

What you describe is a framebuffer. If you use the GBS-8220 as a pass-through (that is, without upscaling by providing a 31khz 480p image and also outputting 480p) then I've found that it does what you describe. It stabilizes the image and removes some of the vertical artifacts you see on some monitors. It's been a while but I seem to remember 50hz mode has centering problems; somebody on a forum solved them by wiring a Raspberry Pi to it and sending specific commands...

I know this GBS approach sounds fiddly but it only costs about $70 (GBS + Rpi); the Zx-Uno (an FPGA board with GPIO and VGA out) costs $78 (70 Eur). That's probably the minimum such a device would cost; whch isn't exactly cheap considering a simple VGA->HDMI upscaler is $20-30.

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Re: MiST VGA Compatibility

Postby skeezix » Sat Aug 27, 2016 3:26 am

I found the GBS-8220 itself to fiddly, but 'more or less' does the job; the MiST doesn't work on 'any' of my TVs without assistance (sigh), so it needs the GBS-8220 to work 'at all', which is a shame. The GBS-8220 itself tends to have the issues noted above.. centering, or wrapping, or others.

So sometimes I'd like upscaling (and its fiddly), or other times I just want an image that works at all (MiST), without all the fiddly.

So the use case for me (maybe unique? :) is something less fiddly; I envisioned it as a simple small little board .. VGA in, VGA out, the ISP or JTAG flash header, and some GPIO and/or buttons for controlling config settings. ie: A VGA to VGA pass through, that cleans up a otherwise goofy VGA signal.

So for MiST ue case.. I coudl plug it into MiST like a little dongle, and get it to work easy. For upscaling case, the GBS-8220 is goofy, could clean it up.

I have heard tale of some goofy things like hooking up an r-pi to it, but thats annoying. I'm trying to simplify my setup, since I've found complex/goofy/fidgety is offputing, and time is so tight.. want to make life easier :)

A better option is to redo or patch the firmware on the GBS-8220, to emit more useful signals; I've heard some action on that front, but didn't find any reports of real progress or releases, but it was sort of hard to find at the time I looked.

As someone who does a lot of electronics hobbyest hacking (I've made my own console/computer from scratch!), its a doable and tempting hack of a project. But also probably more work than its worth because as you say.. there are options :)

*shrug*

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Re: MiST VGA Compatibility

Postby Newsdee » Sat Aug 27, 2016 3:55 am

But it's not just a pass-through... so it's not that simple.

If you want to "clean" the signal to a solid 50hz or 60hz, either you change the source core to run at just the right speed or you add a framebuffer to the output. For the latter, you need memory to store the image and read it back at the right rate, or you get tearing. It adds latency which can become noticeable.

It's probably possible to make something designed specifically for the MiST that only needs to handle the frequencies it outputs; but then it will end up fiddly anyway. The XRGB does have a lot of flexibility but then is built specifically for that purpose. And is very expensive...

Now don't get me wrong. I'd love a cheap way to stabilize the output. Perhaps the ZxUno might be a way.

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Re: MiST VGA Compatibility

Postby ericgus » Sat Aug 27, 2016 4:19 am

I think part of it is just having a display that is flexible enough to accept goofy slightly off signals.. so far I've found Samsung LCD displays to be the most lenient of the LCD monitors ..

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Re: MiST VGA Compatibility

Postby Sorgelig » Sun Aug 28, 2016 12:38 am

Newsdee wrote:Now don't get me wrong. I'd love a cheap way to stabilize the output.

I think, there is no cheap way if you want to get a stable upconverted video from any possible video. The FPGA upscaller is the right way. But what OSSC author did is totally wrong and diminishes FPGA purpose (actually some cheaper MCU alternative will do the job assigned to FPGA in OSSC) . XRGB is not open source and has enough problems, making it not desirable with such price.

If someone will make VGA to HDMI open source upscaller based on FPGA with Audio over HDMI and RAM chip for frame buffer, then i will be the first who will buy it!

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Re: MiST VGA Compatibility

Postby Sorgelig » Sun Aug 28, 2016 12:41 am

Newsdee wrote:Perhaps the ZxUno might be a way.

How it can solve the problem? Do you mean GPIO to control the GBS board?

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Re: MiST VGA Compatibility

Postby Sorgelig » Sun Aug 28, 2016 12:47 am

If only TV PAL/NTSC required to convert then LKV362A does this job nicely at pretty cheap price.
The problem begins when you want to output 31KHz and 15KHz video without reconnecting the cables.


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