OSSC (DIY video digitizer & scandoubler)

[Lord of Pirates]

Can I sign-up on a post-50 waiting list but not leave purchasing information at this point and even cancel if I want to?

Sure - I'm not even accepting any purchasing info yet since the price is not final.

If the 720p mode doesn't work with my Panasonic I might try upscaling the 480p with my XPC-4, although really that's an overly convoluted chain for my tastes. Has anybody managed to test the 720p mode with any consumer LCD TVs (except for Blizzz's Sony) yet? I'm too lazy and stupid to do it for myself.

I wouldn't hold high hopes for any customer TV, especially if HDMI is the only digital input. They are designed only for a couple fixed modes and even a small deviation from spec-defined refresh rates or line counts can cause issues.

Speaking of modes, I did some tests with my SC512-N1-L and found out that the strange color component error takes only place when horizontal total is 1705 pixels - 1704, 1706 etc. are fine. Too bad 1705 just happens to be 5x the dots/line rate of NES,SNES etc. I also noticed some general bugs that Micomsoft hopefully will fix at some point. For example, below is a screencap taken from OSSC's basic display calibration pattern (which is BTW generated at spec-compliant 720x480@59.94Hz) - you can notice vertical banding on the gradient which doesn't exist when connected to a proper monitor. I made a similar setup with PC connected to SC512-N1-L to verify the problem is not OSSC-related, and also tried tweaking all relevant parameters in SC512-N1-L settings.

I'm curious, would it be possible for you to fix FW issues like that if you were so inclined? Not that I'm saying you should and they shouldn't or anything, just wondering if it's possible with the just FW file(s) and the hardware.

[marqs]

I'm curious, would it be possible for you to fix FW issues like that if you were so inclined? Not that I'm saying you should and they shouldn't or anything, just wondering if it's possible with the just FW file(s) and the hardware.

Without any design documents / source code, reverse engineering effort would be quite big. Some of the issues may also be limitations of the hardware itself and not necessarily fixable by firmware. I've seen my share of hardware 'bugs' in TVP7002 chip during this project, and finding workarounds has not been that pleasant job.

[Rune]

Is there any sort of on screen display when you fiddle around with the settings?

[marqs]

Is there any sort of on screen display when you fiddle around with the settings?

Nope - only an on-board character LCD display.

[marqs]

A few days ago I was thinking about the active DVI+audio->HDMI and DVI->VGA converters which were mentioned a few pages back - they are all externally powered, right? I'm asking because I was going to omit 5V power line from DVI/HDMI output as a safety precaution. There is overvoltage/overcurrent protection circuit right at DC input in case an unsuitable/bad power supply is accidentally plugged in, but I don't want to take any chances that a connected display could be damaged. Usually that 5V line is used in plug&play features (not really important here) and as far as I know those converters should be externally powered, but please correct if I'm wrong.

[Guspaz]

DVI+Audio to HDMI adapters are mostly externally powered, but HDMI to VGA (and presumably you're using one of those via a DVI to HDMI adapter) adapters are often bus powered. And while it doesn't impact this current project, pretty much all active DisplayPort adapters are bus powered.

Examples of bus-powered HDMI to VGA adapters:

https://www.monoprice.com/product?p_id=11566

http://www.startech.com/ca/AV/Converter ... 0~HD2VGAE2

And here is a straight-up DVI-D to VGA adapter, which would theoretically be perfect for this:

http://www.startech.com/ca/AV/Converter ... 0~DVI2VGAE

All of those adapters need the power supplied by the HDMI/DVI source.

EDIT: I want to clarify that some bus-powered devices (like that last StarTech adapter) optionally support external power, but some (like the Monoprice one) don't.

[Unseen]

I'm asking because I was going to omit 5V power line from DVI/HDMI output as a safety precaution.

Bad idea unless you want to annoy your users. I don't remember the exact numbers, but IIRC quite a few of my TVs/scalers/capture cards/etc. with HDMI inputs refused to recognize a signal on their input when the DDC 5V line was left unconnected.

[Das Muel]

Yeah, my cheapo HDMI-VGA adapter is bus-powered.

[Guspaz]

It's worth pointing out that it would also break active HDMI cables, like RedMere cables and those with active equalizers. These sorts of cables are typically used either to enable them to be longer than a typical HDMI cable, or to be thinner than a typical HDMI cable. Most (all?) of the many HDMI cables in use in my apartment are RedMere cables, although I still have a large stock of regular cables from before.

In my case I replaced 'em all with RedMere to try to reduce the mess, by making all my HDMI wires much thinner.

The chips in these cables are powered by the HDMI 5v line.

[Fudoh]

same here. Redmere cables all over the place.

[niall]

And here is a straight-up DVI-D to VGA adapter, which would theoretically be perfect for this:

http://www.startech.com/ca/AV/Converter ... 0~DVI2VGAE

Anyone know if this would support 640x480 / 720x480? All I need is a nice scaler to 480p VGA, all of the DVI/HDMI would be wasted on me as I just want to feed some 31kHz CRTs alongside all of the 15kHz tubes. Love to see a daughterboard mk2!

[BazookaBen]

Anyone know if this would support 640x480 / 720x480? All I need is a nice scaler to 480p VGA, all of the DVI/HDMI would be wasted on me as I just want to feed some 31kHz CRTs alongside all of the 15kHz tubes. Love to see a daughterboard mk2!

Hmmmm, I dunno, maybe you should check this link:

http://shmups.system11.org/viewtopic.php?f=6&t=52158

it's all explained there

[lui]

What would be required to switch the scart head with a JP 21 connection? (Unsure if it's possible to simply resolder based on the pictures or not)
Or would there be a possibility of ordering in PCB boards with the aforementioned JP 21 layout for the scart connection?

• * Low latency (<0.2ms) video digitizer and scan converter designed for gamers
  * 3 inputs supporting several formats: RGB-scart (RGBS/RGsB), 3xRCA (YPbPr/RGsB), VGA (RGBHV, RGBS)
  * Linedouble-support for 240p/288p, 480i/576i
  * Linetriple-support for 240p with 4 different sampling configurations (for compatible monitors)
  * Digitization of various EDTV/HDTV/PC modes
  * Quick video mode change, e.g. between 240p and 480i
  * Full-range RGB digital video output
  * Extra features: adjustable scanlines, border mask, Rec. 601/709 selection for YPbPr etc.
  * Configurable Video LPF (4 settings and bypass)
  * Remote control support and 2 PCB buttons
  * microSD-slot for easy firmware updates
  * On-board JTAG-connector and open firmware
  * Will be available as a complete unit and as a DIY kit

Also, regarding the input formats, does the VGA connection not accept RGsB ?

[Lord of Pirates]

I'm curious, would it be possible for you to fix FW issues like that if you were so inclined? Not that I'm saying you should and they shouldn't or anything, just wondering if it's possible with the just FW file(s) and the hardware.

Without any design documents / source code, reverse engineering effort would be quite big. Some of the issues may also be limitations of the hardware itself and not necessarily fixable by firmware. I've seen my share of hardware 'bugs' in TVP7002 chip during this project, and finding workarounds has not been that pleasant job.

Thanks for responding. I presumed something along those lines, but I wanted to ask someone that would know. Now to go back to waiting for an in-depth review .

[marqs]

And here is a straight-up DVI-D to VGA adapter, which would theoretically be perfect for this:

http://www.startech.com/ca/AV/Converter ... 0~DVI2VGAE

Anyone know if this would support 640x480 / 720x480? All I need is a nice scaler to 480p VGA, all of the DVI/HDMI would be wasted on me as I just want to feed some 31kHz CRTs alongside all of the 15kHz tubes. Love to see a daughterboard mk2!

DVI->VGA converters are simple and should support any mode up to some maximum pixel clock - it's a shame that such converter costs over 60 CDN

What would be required to switch the scart head with a JP 21 connection? (Unsure if it's possible to simply resolder based on the pictures or not)
Or would there be a possibility of ordering in PCB boards with the aforementioned JP 21 layout for the scart connection?

That would require cutting some PCB traces and adding jumper wires - an adapter cable would be better solution. If there's more demand for JP21, I may order some boards with that setup later.

Also, regarding the input formats, does the VGA connection not accept RGsB ?

It would have been easy to add support for that but I didn't come up with any use case so it was left out. Which home computers are using that?

[Guspaz]

And here is a straight-up DVI-D to VGA adapter, which would theoretically be perfect for this:

http://www.startech.com/ca/AV/Converter ... 0~DVI2VGAE

Anyone know if this would support 640x480 / 720x480? All I need is a nice scaler to 480p VGA, all of the DVI/HDMI would be wasted on me as I just want to feed some 31kHz CRTs alongside all of the 15kHz tubes. Love to see a daughterboard mk2!

DVI->VGA converters are simple and should support any mode up to some maximum pixel clock - it's a shame that such converter costs over 60 CDN

To be fair, StarTech is not known for low-cost devices, and the Monoprice HDMI to VGA converter that would seem to do the same thing costs $18.29 USD including a 3-foot HDMI cable. They don't seem to make a DVI-D to VGA device, but I'd imagine that's just a matter of a simple adapter, for which they charge $2.28 USD.

DisplayPort to VGA adapters are even cheaper, with passive converters costing $9, and active ones costing $14.

[rtw]

Also, regarding the input formats, does the VGA connection not accept RGsB ?

It would have been easy to add support for that but I didn't come up with any use case so it was left out. Which home computers are using that?

PS2 has RGsB on 480P, SONY included a cable with the Linux kit.

[Fudoh]

yes, but since nobody got that cable anyway, Marqs enabled RGsB on the Scart input. This way one can use a Scart cable with a PS2, leave the system at RGB and use it for both 15khz RGBs and 31khz RGsB.

[Guspaz]

That's a very niche case, because the cable is rare, and only works with progressive scan games and PS2 Linux. PS2 users would seem to be better off using component video, which works with all games/applications and at all resolutions.

[BazookaBen]

You can use component cables for RGsB, you just have to set up 480p blindly. For games where I'm forcing 480p with GS Mode Selector, you can assign a button to hold at startup with Free MCBoot to automatically boot GS Mode selector and automatically load the 480p VGA profile.

[BuckoA51]

PS2 users would seem to be better off using component video

Too noisy especially on PS1 games I've found.

[BONKERS]

PS2 users would seem to be better off using component video

Too noisy especially on PS1 games I've found.

On a CRT? Component doesn't have any noise that i've noticed on my 27" Consumer CRT.

[marqs]

PS2 users would seem to be better off using component video

Too noisy especially on PS1 games I've found.

On a CRT? Component doesn't have any noise that i've noticed on my 27" Consumer CRT.

The PS2 model (SCPH-30004R) I've been using for testing has noise - especially with 15kHz - both on component and RGB outputs, although a litter less with latter. I haven't tested RGsB with that machine (SOG disabled on mobo for 31kHz+ RGBs output), but I guess it doesn't add much noise compared to RGBs. Anyway, LPF is required for noise-free picture.

[Asbrandt]

An Original XBox with a VGA Patched BIOS will also be outputting RGsB and from what I can tell it's easier to get a component cable (or the official breakout box) and use a passive adapter to a VGA connector than it is to get a SCART cable for that system in general.

[Guspaz]

I don't follow, the SCART cable for the XBOX is £11.99 from RGC. How is modding your BIOS and then using component cables with VGA adapters and hoping the monitor supports SoG any easier than just paying £11.99 for the SCART cable?

[Asbrandt]

I don't follow, the SCART cable for the XBOX is £11.99 from RGC. How is modding your BIOS and then using component cables with VGA adapters and hoping the monitor supports SoG any easier than just paying £11.99 for the SCART cable?

Didn't see that he made XBox stuff last time I looked at his site and here in the US half the time you pick up a working XBox it comes with a component cable already.
Also, getting 480p+ RGB out of an XBox requires the patched bios and dealing with SoG regardless of what cable you get.

[Guspaz]

People here seem to really loath to use component instead of RGB, but it's mathematically identical to RGB. BuckoA51 said that he compared the official VGA and component cables and found the image quality to be identical.

[BuckoA51]

BuckoA51 said that he compared the official VGA and component cables and found the image quality to be identical.

On Xbox, yeah I did. I also had some weird picture problems with VGA, I can't remember exactly what, like a rolling band of discolouration in certain scenes I think. I'd definitely just use component on the original Xbox.

[BONKERS]

The PS2 model (SCPH-30004R) I've been using for testing has noise - especially with 15kHz - both on component and RGB outputs, although a litter less with latter. I haven't tested RGsB with that machine (SOG disabled on mobo for 31kHz+ RGBs output), but I guess it doesn't add much noise compared to RGBs. Anyway, LPF is required for noise-free picture.

I wonder if different models are different in this regard?

[lui]

That would require cutting some PCB traces and adding jumper wires - an adapter cable would be better solution. If there's more demand for JP21, I may order some boards with that setup later.

It would have been easy to add support for that but I didn't come up with any use case so it was left out. Which home computers are using that?

Well if it is indeed as easy as you say, consider adding support.
(I was referring to the Playstation 2 VGA cable as mentioned above when I asked) But include the format mainly for completeness sake, considering someone else will probably ask for this feature again later down the line.

Additionally you could add a dropdown box for JP-21/Scart on the pre order form, to gauge interest: (https://docs.google.com/forms/d/1RPMoXK ... 4/viewform)