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Testing The OSSC Pro’s New Scaler Mode With Weird Old PCs


The OSSC Pro is the brand new video scaler from Markus Hiienkari, who brought us the mighty Open Source Scan Converter back in 2016. This scaler supports VGA, component and RGB SCART input and I’m helping to test a prototype unit with some old PCs to help iron out some bugs - so let’s take a look!


If you’ve been into this retro computing hobby for a decent length of time, like I have, you’ll no doubt have come across this wonderful little box of tricks. Of course, this is an OSSC, or Open Source Scan Converter, and for the uninitiated, essentially what it does is it can take a video signal from anything that can output VGA, component video, or RGB SCART, and it can clean that signal up, it can upscale it, it can line multiply it, and it can make it look absolutely fantastic and crispy and high resolution on modern HDMI displays like this one - and in my particular use case as a YouTuber, of course, I can also capture those signals much more easily than I could from the original hardware.

So this is a very important part of my toolbox. Now a few weeks back I was contacted by a good friend of mine, a chap called Bob, who runs RetroRGB - you probably will have seen me on his channel a couple of years ago, and I’ve also done some writing for his website - and he does tend to message me all sorts of random stuff all the time, but this was of particular interest because he’d been contacted by Markus, who designed the OSSC, and is now working on the OSSC Pro and indeed there has been a batch of these that’s been sold already and they are in the hands of some very lucky people. And Markus was looking for somebody to help test PCs specifically, all sorts of weird and wonderful PCs. And Bob happened to mention that I owned a 1981 IBM 5150, for example, an NEC PC-98, stuff with Voodoo cards in, stuff with S3 ViRGE cards in and everything in between.

And so Markus contacted me directly and asked if I wanted to help out with testing the OSSC Pro. And who was I to argue? The OSSC, like I say, has been a really, really useful tool to me over the years and anything that I can do to help out with the new version, I’m more than happy to get involved with.

So that’s what I’m going to be doing in this video - testing it with some different PCs. This isn’t a comprehensive review. This is still under very, very heavy development, but I thought I would just show some of the work that I’ve been doing with Markus to make this the best possible device that it can be.

So I think without further ado, let’s get on and start testing with some of these devices.

So the first thing I thought I would check out was my NEC PC-9821. Now this thing isn’t quite a PC, it’s not fully 100% IBM compatible - it’s a bit weird, and that is a story that I have covered on my channel in a couple of videos so far.

It’s a bit of an ongoing series, so if you’re interested in learning the history of these machines, I’ll link those in the usual places, but yeah, as you can see, this thing has absolutely no problems whatsoever with the OSSC Pro. Apologies for the flickering on the CRT here, it’s a 70Hz display and I couldn’t quite get my camera dialed into that because I don’t have a fancy camera like some of these big boy YouTubers, but yeah, the OSSC Pro handled it absolutely fantastically well - the picture is so super sharp, it looks absolutely brilliant.

And of course, I had to capture this directly as well over HDMI just to show you the full extent of how good it really does look and really, really pleased with this. I think it looks great.

Now, one of the things that I did want to test with the PC-9821 was the 24kHz mode, which these machines apparently have - I’m still learning my way around this machine, I’m quite new to it - but apparently you can activate that by holding down “Graph” and “1” while pressing the power button. And as you can see from the OSSC Pro, the machine does very briefly go into that mode before switching back. So I guess that’s not supported on this later machine, which is a bit of a shame because it would have been cool to test with that.

But hey, I guess at the very least, the Pro does detect the signal. So I guess that’s probably quite a good sign that it would work. And if I can get it working in future, then of course I will post a bit of an update with that.

Ah, now we’re talking! So this is a lovely vintage PC - it’s a Pentium 233 MMX and you will have seen this on my channel before.

And this PC has an S3 ViRGE card in it which went down in history as not being very fondly remembered. It’s not a great graphics card but that actually makes it quite useful for testing because the video output of this card has always been pretty terrible - it’s always looked quite soft, and picked up quite a bit of interference and it’s something I’ve never been able to fix.

I even recapped the card at one point and that didn’t make any difference whatsoever to the output - so I think it’s just always been a terrible graphics card!

But there are S3 ViRGE accelerated games out there, and I was under the impression that they ran at kind of weird resolutions and refresh rates, and that that might be quite useful for testing the OSSC Pro, so I thought this would be the ideal machine for that.

There is another piece of hardware that will also help on that front, which I’ll mention in a second, but yeah, first things first, let’s boot into Windows and just go through all of the standard Windows 95 resolutions that we know and love, so 640x480, 800x600, all the way up to 1600x1200, and the OSSC Pro handles all of those absolutely fantastically well.

No issues at all, very quick switching between the resolutions as well, which is great to see. And, I must say, the output from the OSSC Pro is so much cleaner and sharper than it is on the native picture that you see on the left, the raw signal from the graphics card, so that was really surprising to see.

So I dropped into DOS to check out some S3 ViRGE accelerated DOS games, and first up was Whiplash, which is a personal favourite of mine. Now this game actually looks and runs worse on the ViRGE than it does just using the software renderer on this machine, so definitely not recommended, and that is something that I discovered in a previous video, but of course the OSSC Pro handles it perfectly fine.

I also checked out Actua Soccer, which is the S3 ViRGE accelerated version as well, and again, no issues whatsoever with that.

Some of these games, when they start up and when they’re going through the menus and things, do switch through resolutions quite quickly, which, of course, back in the old CRT days was no problem whatsoever, and with modern displays can cause a lot of problems, in particular with my capture device, so it’s great to see the Pro just you know, flicking through those quickly with no issues whatsoever.

And finally in the world of DOS, I thought I’d just quickly check out Terminal Velocity, just to give me an excuse to play it really because I love this game. It looks and runs great on this machine - a bit of a weird oddball release, because it is optimised for that S3 ViRGE card, but again, it looks great on the OSSC Pro.

And I was actually going through and checking the resolutions of these games, and they all run at 640x480 at 60Hz, so incredibly boring from a video signal perspective. So I thought I would boot back into Windows and try to do something that would stretch the Pro a little bit further.

So this is Croc - the PC’s answer to Mario 64, the finest 3D platformer on Windows 95, if you don’t mind me saying.

And this also has native ViRGE support and runs at 512x384 at 70Hz, which is a bit of a weird video mode, but very pleased to say that the OSSC Pro handles that perfectly fine too - and if we go to a direct capture of this game over HDMI, as you can see, it’s looking super crisp. It looks absolutely fantastic.

So another win for the OSSC Pro!

Now this PC has another trick up its sleeve, and that trick comes in the form of an Orchid Righteous 3D. Now if you’re a bit of an enthusiast of DOS gaming, you’ll probably recognise that as the very first Voodoo card. And again, it can output some interesting video signals.

So I thought I’d check out GLQuake to start with and it handled that perfectly fine in 640x480 as you might expect, and looking super crisp on the OSSC Pro - really good upscaling and cleaning up of that video signal. In fact, this, this almost looks like a native software capture. It’s that good.

But I did run into a problem trying to run GLQuake in 512x384, and I believe this is trying to use a refresh rate of 72Hz, which is quite unusual, and the OSSC Pro doesn’t like it - it starts outputting a weird signal that my cheap and cheerful 1080p office monitor doesn’t like.

So yeah, that’s a failure as far as the Pro is concerned. I fed that data back to Markus and he says that he has actually very recently picked up a PC of this era with a Voodoo card with GLQuake specifically for testing this particular mode.

So he was aware of it but of course great to have that confirmed on another piece of real hardware and hopefully that’s something that he can fix for a future firmware update.

Of course no PC graphics test is complete without native DOS - and I’m talking actual proper DOS here, DOS 6.22, and this is running on my lovely RM 486 DX4/100. I really love this machine, it’s got an Orpheus sound card in it, and one of my absolute favourites in my collection - of course, RM made all of our school PCs here in the UK, so fond memories of using one of these- misusing one of these at school…

…to play Doom, no less, which, of course, I have to use for this test here. And as you can see, the OSSC Pro handles that absolutely no problem whatsoever, and I’ve had no end of problems over the years trying to capture decent video from DOS, using various different scalers and different capture devices. I think the StarTech USB3HDCAP is probably the closest I’ve ever got, and that is what I used in the early days of my channel but now, of course, I can upscale the DOS video signal to 1080p, and I can use a 1080p capture device like the Elgato Cam Link, which just makes life so much easier. So great to see that this is working well.

And again, these PCs, as they go through processes and stuff, they do switch through different resolutions.

And great to see that the OSSC Pro handles those perfectly fine, no hangups or delays or anything like that, so that’s great to see.

And again on this machine, while I’ve got it out I thought I’d just pop into Windows. Of course there’s nothing too challenging here, but it gives me an excuse to play Chip’s Challenge and I don’t need much of an excuse to play that.

Of course no discussion about the history of the PC is complete without this!

The OG, the 1981 original DOS PC, the IBM 5150 of course, and again one of my favourite things in my collection. And I know I say that a lot but I’ve pulled out all the stops for this video and for this testing process just for you!

So yeah, this is quite a difficult one because it has a CGA card in it and CGA is a TTL signal which isn’t electrically compatible with-

Well, with much really!

I’ve always had issues with this trying to capture video from it over the years, but I did come up with a setup that works and that uses something called a CGA2RGBv2 made by GG Labs - and no, they haven’t sponsored this video or anything like that, it’s just a device that I’ve found works very well - and it converts that TTL signal into a normal RGB signal.

The trouble being that the resulting signal is still 15kHz, and indeed the only device I’ve managed to find over the years that can handle it is the original OSSC.

So of course I had to test it with the new Pro, and of course, really pleased to see that it is working great with that, and I can get in there and play some more Commander Keen - Commander Keen 4, the CGA version - fantastic game!

I actually did some live streaming with this setup, with the OSSC, in the very early days of my channel, in the deepest, darkest depths of lockdown so great to revisit those days and to have a modern equivalent.

Not sure about comparing performance between the two, switching between those different video modes and stuff - that’s probably something I’ll have to look at in a future video, but yeah, pleased to report that it works with this ancient machine as well.

So OSSC Pro PC testing going really well, as I’m sure you can see.

Just a couple of minor issues which of course I fed back to Markus and should hopefully be fixed in an upcoming firmware update - and this absolutely isn’t the last of it, I’ve got so many more machines here that I want to test with this device - and one of the things that he’s adding which is quite exciting is, composite and s-video input support.

This is expandable - it has an expansion port on the side, and it means that it can have new video inputs and outputs basically plumbed directly into its FPGA chip. So there’s already a downscaling analog video output for it, so you can take your high resolution HDMI 1080p signals and downscale them to 240p for display on an old fashioned TV if that’s what you want to do.

I actually watched a video about that just earlier today, which I’ll link to down below if you’re interested in that functionality. But yeah, it would be cool to see some more input functionality, because I’m currently using a RetroTINK 5X for that, and this is absolutely fantastic. It’s got component and composite video inputs, it’s got s-video, it’s got RGB SCART, of course quite a big overlap with the OSSC Pro here, and the benefit of this is that basically you plug it in, you switch it on, and it works - it looks fantastic straight away, which we’re seeing with the OSSC Pro on the PC side.

So if there was one device that could do it all - and I haven’t got my hands on the RetroTINK 4K yet, so that might also be a contender - but yeah, if this can grow into a device that can do it all, then that would make me a very happy boy indeed.

But hopefully it bears reiterating that I’m not officially associated with the project in any way - I’m not a spokesperson, I’m not being paid to advertise this thing, I was just asked to help out with the testing side of things because of some of the hardware that I have here.

So, hopefully that’s come across in the video, really excited about all of this stuff and anything that makes my life a bit easier as a YouTuber, and as a gamer, and a computer enthusiast, has to be a good thing.

So thank you ever so much to my supporters on Patreon, Ko-Fi, and the YouTube channel member page for all of your financial support for the channel - it makes all of this possible and pays for this studio and stuff - and of course, a big thanks to you for watching.

Subscribe to the channel for future updates on the OSSC Pro and everything else that I’m doing with all the retro hardware and software that I have here. That’s all I have for now. Thank you ever so much for watching, and hopefully see you next time!

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Relevant Links:
RetroRGB Interview:
RetroRGB Website:
PC-9821 Part 1:
PC-9821 Part 2:
OSSC Pro Downscaling Video From MarcoRetro:

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