OSSC (Open Source Scan Converter) with an Amiga

[eXeler0]

Originally Posted by turrican9

Does the GBS8200 have a 50Hz mode, or will it only do 60Hz?

I think it does just fine but depending on your monitor it could result in possible artefacts.
Check Stedy's good blog on his experiments with the gbs82xx

https://ianstedman.wordpress.com/gbs-82xx-experiments/


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[turrican9]

Originally Posted by eXeler0

I think it does just fine but depending on your monitor it could result in possible artefacts.
Check Stedy's good blog on his experiments with the gbs82xx

https://ianstedman.wordpress.com/gbs-82xx-experiments/


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Thanks. I read through that experiment, but it is still not clear to me if this scandoubler has the possibility to output 50Hz or if it only converts the Amiga RGB signal from 50Hz to 60Hz. 60Hz is not smooth gameplay.

also, the banding he writes about sounds like the monitors pixel and phase clocks needs to be finetuned.

[thgill]

The GBS boards are garbage.

The suffer from:

• 60hz only output. Good for compatibility with LCDs, terrible for smooth 50hz scrolling (I have heard of hacks to force 50hz though).
• Massive input lag. We are talking 2 frames of lag. If you use it with a LCD, than there is even more input lag.
• Doesn't support 24/32 bit color. Will be dithered with massive banding.

[turrican9]

Originally Posted by thgill

The GBS boards are garbage.

The suffer from:

• 60hz only output. Good for compatibility with LCDs, terrible for smooth 50hz scrolling (I have heard of hacks to force 50hz though).
• Massive input lag. We are talking 2 frames of lag. If you use it with a LCD, than there is even more input lag.
• Doesn't support 24/32 bit color. Will be dithered with massive banding.

Thank you for confirming

[thgill]

In case you guys are interested, I posted up another OSSC video. This time with the Neo Geo.

[ Show youtube player ]

[eXeler0]

Originally Posted by thgill

The GBS boards are garbage.

The suffer from:

• 60hz only output. Good for compatibility with LCDs, terrible for smooth 50hz scrolling (I have heard of hacks to force 50hz though).
• Massive input lag. We are talking 2 frames of lag. If you use it with a LCD, than there is even more input lag.
• Doesn't support 24/32 bit color. Will be dithered with massive banding.

Ive had mine for a bunch of years and kind of still hoping there will be a new release some day. I see some newer revisions of the GBS boards but It seems they all use the same old chip.

So while its not a *good* solution, it does kind of work and hey...vyou can buy it for something like $17.. Hard to beat if you need a "plan b"...

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[jbenam]

Originally Posted by thgill

The GBS boards are garbage.

The suffer from:

• 60hz only output. Good for compatibility with LCDs, terrible for smooth 50hz scrolling (I have heard of hacks to force 50hz though).
• Massive input lag. We are talking 2 frames of lag. If you use it with a LCD, than there is even more input lag.
• Doesn't support 24/32 bit color. Will be dithered with massive banding.

I can confirm this as well. I tried using one for more than 10 minutes, but oh geez, I really can't. Good thing a friend wanted one and I could test it for a while before giving it to him

[turrican9]

So BenQ BL 702A and BL 912 connected via RGB to VGA gives a perfect LCD/LED picture at 15KHz and smooth 50Hz scrolling. Indivision ECS also gives a very nice picture but has some ghosting and has issues with banding when used with ACA 500. Probably some interference. 50Hz mode also works well, appart from it forgetting it's settings randomly on coldboots. It has scanlines, allthough a bit too dark for my taste. With a scaline generator connected it looks good.

I would like a cheap external scandoubler for Amiga that does 50Hz with a nice picture. This way I could easily connect any of my Amigas to it and also put the scanline generator in between it and the screen. OSSC is too expensive for me and has alot of stuff I don't need. And I only want to use an item like this for my Amigas.

But again, the above mentioned BenQ screens does the job perfectly with no scandoubler, but I would like scanlines. They are not a must, but I would like the option. Scanline generator does not work at 15KHz.

[eXeler0]

@turrican9 apart from the GBS8200 which I use to connect the A600 to VGA when the HDMI output from the Vampire isnt used, I have a BenQ BL702 for my A1200. (LCD TV with 4:3 ratio connected with RGB to Scart cable for the A500) and a CD32 hooked up to an old skool CRT TV through Scart.

Of the 4(5) options above, the BenQ 702 work probably the best from a picture quality vs flexibility vs price standpoint.
You are however limited to that small screen. So by buying an external scandoubler you buy yourself flexibility to hook your devices up to different screens. If you dont plan to do that then there are probably more affordable solutions.

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[turrican9]

Originally Posted by eXeler0

@turrican9 apart from the GBS8200 which I use to connect the A600 to VGA when the HDMI output from the Vampire isnt used, I have a BenQ BL702 for my A1200. (LCD TV with 4:3 ratio connected with RGB to Scart cable for the A500) and a CD32 hooked up to an old skool CRT TV through Scart.

Of the 4(5) options above, the BenQ 702 work probably the best from a picture quality vs flexibility vs price standpoint.
You are however limited to that small screen. So by buying an external scandoubler you buy yourself flexibility to hook your devices up to different screens. If you dont plan to do that then there are probably more affordable solutions.

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Well, I don't want to connect my Amigas to big screens anyway. Even the 17 inch BenQ BL 702A are quite a bit bigger than the old 14 inch CRT TVs and monitors which is the size many people used. And also the size I feel stuff where made to look good on. I actually have two 702As and one BL 912. I bought enough of these in case they would dissapear from the market soon. I have to say that the BL 912 is almost too big for me, but also has a rather perfect picture. The red colour on the BL 912 needed to be manually set to get a more warm picture like the 702As have.

As for scanlines I have several options. I can my A600 which has the Indy ECS. I can put my other Indy ECS in one of my A500s. But not with the ACA 500 as it gives quite bad interference. Ironic since both components comes from the same company. I can then choose to use the built-in scanlines or use it together with a cheap scanlines generator I have that gives softer scanlines. I also have my A1200 with the Indy AGA MK2 which you can actually set how dark you want the scanlines. AGA MK2 is missing vsync but I have managed to make a profile that is finetuned to 50.137Hz. This was the closest I got to perfect smoothness. It will have a small screen tear very rarely.

[jarp]

Just for the record; new firmware for the OSSC were released with profiles support. This means that one can dial in pixel perfect settings for various Amiga's screen modes and save them as a "Amiga" profile.

IMO this was the last major drawback which has now been addressed.

[puppypc]

Great! Hopefully, the next batch will be ready by february, I'm anxious to get one

[seb132]

Amazing product! I subscribed to the waiting list...


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[jarp]

Again for the record; new firmware was released which now supports x4 and x5 modes. Read: 288p mode can be scaled to 1440p which is just perfect for 1440p monitor owners.

[jbenam]

So yep, I've just got the email for my OSSC! Ready to pull the trigger on one, but one last question: how smooth are 50hz games on the OSSC? That's a big part of the "CRT experience" for me, along with scanlines. If it manages to nail it, this is gonna be my best retro-focused purchase ever!

My new monitor should be able to do 50hz easily - it means that it should just sync down to 50hz and be just as smooth as a CRT, right?

Thanks!

[thgill]

Yes.

If your LCD does 50hz, scrolling will be smooth like a crt. Pretty much all of Dells modern lcds do 50hz no problem. They are what I use. However I do have an Asus monitor that will display 50hz but the scrolling is choppy as the monitor internally converts 50 to 60hz.

The OSSC doesn't have a built in frame buffer, so it doesn't affect the refresh rate. 60hz in = 60hz out. 50hz in = 50hz out. It also works with oddball refresh rates like from the x68000 where some games like Akumajou Dracula (Castlevania) run at 56hz.


Providing your display supports it, you are golden.

[Jope]

Indeed. With the OSSC any smoothness is strictly down to your display. Some monitors do not respect the frame rate, but instead always force the panel to 60Hz and perform the frame rate conversion internally.

[jarp]

Also one must understand, that some monitors may even refuse to sync altogether. The OSSC outputs what Amiga outputs and if your monitor does not like it then no sync. This is the con of not having a framebuffer but then again not having a framebuffer is whole point.

If I understood correctly though, monitors are good at syncing to weird modes. My dirt cheap Acer will sync to pretty much everything my Amiga outputs, all weird resolutions, wicked refresh rates etc. But TVs may be more picky.

[Jope]

That is my experience too, TVs are stricter with regards to sync ranges. The Amiga is also annoyingly a tiny bit under 50Hz, sometimes monitors have a hard lower limit of 50Hz and will refuse to play.

[trixster]

I'm toying with buying one of these for use with my PS1, Saturn and SNES.

At the moment they're connected to my plasma tv via a scart switchbox and i'm generally pretty happy with the picture quality. The OSSC is a lot of cash to trip out so is it worth it? When you factor in VAT, a remote and delivery you're looking at £170ish.

Is the difference night and day?