OSSC (DIY video digitizer & scandoubler)

[Unseen]

I don't think anyone has made an NESRGB-style mod for the C64 yet, for example.

The main reason for that is that the NES' video chip makes it easier to identify the current pixel's color/palette index. The C64's VIC does not have any comparable features, so a NESRGB-style modification would have to identify the color based on the actual luma and chroma outputs. The VIC outputs only 9 different luma levels (very old chips are even limited to 5 luma levels), so you need to do phase comparison of the chroma signal to exactly identify the current pixel's color and at that point you could just as well use a real PAL/NTSC color decoder.

There is one solution though that offers something slightly similar to NESRGB: The Turbo Chameleon 64 is an expansion port cartrige with a VGA output. It uses a full VIC-II reimplementation in an FPGA to generate a VGA "copy" of the C64's picture.

[ApolloBoy]

The Turbo Chameleon 64 is an expansion port cartrige with a VGA output. It uses a full VIC-II reimplementation in an FPGA to generate a VGA "copy" of the C64's picture.

The problem with the Turbo Chameleon is that it's ridiculously overpowered for what it is, and it's also nearly $300 which is very cost-prohibitive if you just want better quality video from a C64. The TIA chip in the 2600 and GTIA in the 5200/Atari 8-bit actually work in much the same way as the VIC-II, and since both of those now have RGB boards available I can't see why a similar solution for the C64 can't be possible.

[BuckoA51]

The C64 already supports s-video, and the Framemeister can take that. I've not personally seen the C64's s-video output, but generally there isn't a huge difference between s-video and RGB.

It's bad, worst I've seen, even with a Lumafix installed it's fairly bad, the FM does an OK job with it though.

[Unseen]

The problem with the Turbo Chameleon is that it's ridiculously overpowered for what it is

To be able to work as an expansion port cartridge, it has to include a full 6510 replica in its FPGA in addition to the VIC-II - otherwise it would not be able to determine if a write access in the D000-D3FF area is meant for the VIC registers or the RAM below (same for the color RAM). Due to the way it works, it also cannot cope with an expansion port switch to use other cartridges with it, so it's a good idea to implement some common ones too (and they're not that complicated compared to the rest). You could certainly argue about the 1541 emulation, but I suspect that it doesn't require that much resources if the drive and C64 CPUs are handled by time-multiplexing the same 6502 core.

The TIA chip in the 2600 and GTIA in the 5200/Atari 8-bit actually work in much the same way as the VIC-II, and since both of those now have RGB boards available I can't see why a similar solution for the C64 can't be possible.

In a 2600, a pixel can get its color from only four different color registers (player/missile 0, player/missile 1, playfield/ball, background). If you program these with four distict luma levels, you can use an ADC on the TIA's output to determine which color should be shown on the RGB output.

On the C64, a single pixel can get its color from the border register, background register, 8 base sprite color registers, two additional multicolor sprite color registers, three additional background color registers for ECM, the color RAM, two more colors from the screen RAM (hires/multicolor graphics) and a number of side effects (e.g. ghost byte, 856x gray dots, forced black with ECM+multicolor). There aren't enough distinct colors available in the system to use the same color source reconstruction that is possible with the TIA.

[Blair]

trying a different camera this time.

Samsung LN40+OSSC line 3x (TV can't accept line 4x or 5x without an additional processor) scanlines: 100%)

[eric90000]

Any Samsung KS7000/KS8000 users out there having issues with dropping sync in Line x 5 mode? Got this TV yesterday and have only tested a Japanese Mega Drive so far, all other modes seem to hold sync but line x5 drops every few seconds...any OSSC settings I could change to help it keep sync?

[Galdelico]

Any Samsung KS7000/KS8000 users out there having issues with dropping sync in Line x 5 mode? Got this TV yesterday and have only tested a Japanese Mega Drive so far, all other modes seem to hold sync but line x5 drops every few seconds...any OSSC settings I could change to help it keep sync?

Out of the box, and without messing around too much yet (from the OSSC Wiki):

Allow TVP HPLL2x
Controls whether video digitizer H-PLL uses 2x sampling clock internally on supported video modes.
On: Enables 2x H-PLL, generally reducing jitter at the price of inaccurate sampling phase due to internal bug. [default]
Off: Disables 2x H-PLL, which might help with Line5x stability.


On a different note, guys. Anyone here had an experience with Iiyama monitors for gaming? Even better, anyone ever tested one with the OSSC?
I'm fairly confident now - after talking to different people who could trigger the very same image retention issues I experience with my IPS monitor - that VA/AMVA panels could be a safer bet (as per Xyga suggestion, a while ago), for 480i sources.
So, I'm eyeing the Iiyama ProLite XB2783HSU-B1 - an apparently solid all-rounder 27", under 250 euros - but it's surprisingly difficult to find accurate feedbacks on it, when it comes to gaming.

[Thomago]

So, I'm eyeing the Iiyama ProLite XB2783HSU-B1 - an apparently solid all-rounder 27", under 250 euros - but it's surprisingly difficult to find accurate feedbacks on it, when it comes to gaming.

Stay far from that one! I'm owning one of these and am currently trying to find a replacement for the following reasons:

- F*ucked up gamma, which leads, amongst other things, to excessive banding.
- Extremely slow panel. To fight that, iiyama employs excessive Overdrive, which leads to the usual artifacts. Also, Overdrive is in effect even if the respective option is set to "Off".
- Useless/disfunctional aspect ratio controls: You can only choose between 16:9 and 1:1 playback (and that only for select resolutions). A simple 4:3 option is nonexistent.

[Galdelico]

I'm sorry to hear you've found so many issues with that monitor, Thomago, but thanks for the feedback.

Are you looking at anything specific, as an alternative?

[Xyga]

So, I'm eyeing the Iiyama ProLite XB2783HSU-B1 - an apparently solid all-rounder 27", under 250 euros - but it's surprisingly difficult to find accurate feedbacks on it, when it comes to gaming.

http://shmups.system11.org/viewtopic.php?f=6&t=52761

It's kind of an old monitor now already, and there don't seem to be many similar ones like the Benq BL2700HT anymore (afaik) although that segment ws popular for about a couple of years (FHD 27" VA I mean)
-
EDIT: I see what Thomago just posted before I could publish this post, well, this is either a translation of what we call an old monitor (definitely not up to today's expectations anymore) or a shitty revision (not impossible since the model has been around for a while and modified more than once, BenQ also used to do this).
-
The thing that's the most likely to be a letdown with FHD monitors is the scaling, which has never been really great in most cases, but hasn't gotten any better from what I could see these past couple of years, especially considering that we're using sharper and cleaner external scalers today. 480p is what you could expect from it, no better nor worse than on most TVs that aren't Sony, but the most important, 720p, is really hit or miss. Bar prad.de most scaling-interpolation quality test around are completely useless, so it's impossible to know if something like the OSSC will scale good without showing obvious artifacts, or ruin everything.

The latest two FHD monitors I've had (HP 27xw and Samsung S32F351) although performing extremely well in most areas, did an okay scaling job but not perfect when looking closely, slight uneven patterns were still visible when displaying with fake scanlines effects.
x4 and x5 modes wouldn't work properly, x5 even displaying with black borders on top and bottom no matter what instead of letting a number of lines out like it should be, I'm guessing there's something in the OSSC signal in x4 and x5 that your average FHD monitor today doesn't like.

Don't expect too much from the monitor's settings in regards to aspect ratio and size control, the huge majority of those suck at it.
Even though 4K displays abuse of interpolation where it's not even needed, they're still a better choice when it comes to accepting a broader number of multiplied sources from the OSSC.
4K VA monitors are still excessively rare, but they're coming around, step-by-step.

PS: also sorry to really, really sound like a broken record, but you're aware screen burn/persistent pixels after a hardcore flickering bob job likely can happen on VAs too.
Less likely than with IPSes by the returns indeed, but while being 'safer' VAs aren't guaranteed to be burn-proof either.
You know my opinion; focusing on seeking the ideal display for that 480i OSSC bob job is quite an hazardous quest, I'd still recommend using other processors with full deinterlacing, but of course at the expense of lag...(or getting a CRT at the expense of room/space) :p

[Thomago]

I'm sorry to hear you've found so many issues with that monitor, Thomago, but thanks for the feedback.

Are you looking at anything specific, as an alternative?

Don't let me get started on this... since last year I've tested (I think) more than 20 monitors.

What I'm looking for:

- 24" or more, 27" preferred
- FullHD (I wouldn't mind 4k but am not willing to pay 200-300 € extra for that), 16:9
- ergonomic stand
- not curved
- at least two digital inputs (this is a must), one HDMI
- antireflection coating
- decent picture quality including no backlight bleeding (every IPS display I've tested had insufferable backlight bleeding, so my search is down to VA)
- no excessive lag
- 50 and 70 Hz compatibility (for PAL stuff and Mode13h DOS games - this is a must)
- aspect ratio controls including a 4:3 option (a must)
- decent scaling
- decent OSSC compatibility

There's no monitor on the market that fits these requirements.

Currently I'm waiting for refunds from my purchases of the Samsung S32F351FUU (can't do 70 Hz) and AOC Agon AOC Agon AG272FCX (too many inadequacies to justify its steep €400 price point), so I can try the Samsung C27F591. That one's far from what I'm looking for, but well... it's somewhat of a last resort.

[Xyga]

Wow, you expect too many things at once IMHO, you could circle 20 more monitors and even the best candidates will have a couple of things missing/sucking.

How did you like the S32F351FUU leaving aside the missing 70Hz requirement ? I like it a lot for its quasi-glossy very open and contrasted, smooth, clean and liquid picture.
Scaling isn't the best, overdrive could help a '0.5' intermediary setting, and I had hope for FreeSync support because several product pages claim it's there but erronously so it seems.
Still worth the price for the quality picture IMHO, maybe not as a PC monitor, but it beats all 32" FHD TVs afaik.

[Galdelico]

PS: also sorry to really, really sound like a broken record, but you're aware screen burn/persistent pixels after a hardcore flickering bob job likely can happen on VAs too.
Less likely than with IPSes by the returns indeed, but while being 'safer' VAs aren't guaranteed to be burn-proof either.
You know my opinion; focusing on seeking the ideal display for that 480i OSSC bob job is quite an hazardous quest, I'd still recommend using other processors with full deinterlacing, but of course at the expense of lag...(or getting a CRT at the expense of room/space) :p

Oh, nono, I remember what you said about it. ^_-
Point is, I recently spoke with a guy on GAF who owns a pretty old - and quite impossible to find nowadays - Dell VA monitor, and he tried to trigger the issue on it, which resulted in no problem at all (I'll get back at his messages and post the model here too). That, on top of what you told me about VA panels in the past, led me to gamble on one of them one last time. I'm gonna retire my old 24" TN Asus anyway by the end of July, so it's something I'm looking at regardless.

http://shmups.system11.org/viewtopic.php?f=6&t=52761

It's kind of an old monitor now already, and there don't seem to be many similar ones like the Benq BL2700HT anymore (afaik) although that segment ws popular for about a couple of years (FHD 27" VA I mean)

Yeah, I've been pointed to that monitor already. As you said, I haven't been able to find one anywhere, aside from one available on Italian Amazon, which goes for more than 700 euros, and also comes from a pretty questionable seller.

The thing that's the most likely to be a letdown with FHD monitors is the scaling, which has never been really great in most cases, but hasn't gotten any better from what I could see these past couple of years, especially considering that we're using sharper and cleaner external scalers today. 480p is what you could expect from it, no better nor worse than on most TVs that aren't Sony, but the most important, 720p, is really hit or miss. Bar prad.de most scaling-interpolation quality test around are completely useless, so it's impossible to know if something like the OSSC will scale good without showing obvious artifacts, or ruin everything.

The latest two FHD monitors I've had (HP 27xw and Samsung S32F351) although performing extremely well in most areas, did an okay scaling job but not perfect when looking closely, slight uneven patterns were still visible when displaying with fake scanlines effects.
x4 and x5 modes wouldn't work properly, x5 even displaying with black borders on top and bottom no matter what instead of letting a number of lines out like it should be, I'm guessing there's something in the OSSC signal in x4 and x5 that your average FHD monitor today doesn't like.

Yeah, my 24" FHD Asus - even though it's compatible with pretty much everything the OSSC throws at it - does some oddball job, with scanlines, pretty much with every scaling past 2X.
Just out of curiosity: would 1440p be a better choice, in terms of chances to get something that doesn't mess around with the IQ too much?

[Thomago]

Wow, you expect too many things at once IMHO, you could circle 20 more monitors and even the best candidates will have a couple of things missing/sucking.

The list is somewhat of an ideal, I'm very much willing to make compromises. That said, the BenQ BL2706HT was pretty much perfect, if it wasn't for excessive backlight bleeding (I actually tested three BL2706HTs; every one of them had it).

How did you like the S32F351FUU leaving aside the missing 70Hz requirement ?

I didn't thoroughly test it due to its 70 Hz incompatiblity, but it seemed nice so far. However, I didn't particularly care for it's glossiness. Seemed to make me dizzy.

[Galdelico]

Don't let me get started on this... since last year I've tested (I think) more than 20 monitors.

What I'm looking for:

- 24" or more, 27" preferred
- FullHD (I wouldn't mind 4k but am not willing to pay 200-300 € extra for that), 16:9
- ergonomic stand
- not curved
- at least two digital inputs (this is a must), one HDMI
- antireflection coating
- decent picture quality including no backlight bleeding (every IPS display I've tested had insufferable backlight bleeding, so my search is down to VA)
- no excessive lag
- 50 and 70 Hz compatibility (for PAL stuff and Mode13h DOS games - this is a must)
- aspect ratio controls including a 4:3 option
- decent scaling
- decent OSSC compatibility

There's no monitor on the market that fits these requirements.

Currently I'm waiting for refunds from my purchases of the Samsung S32F351FUU (can't do 70 Hz) and AOC Agon AOC Agon AG272FCX (too many inadequacies to justify its steep €400 price point), so I can try the Samsung C27F591. That one's far from what I'm looking for, but well... it's somewhat of a last resort.

Oh man, and I thought I was on a quest...

Some prerequisites I can agree on very much, so I can understand why you don't want to compromise on certain aspects.
One thing I'd personally want to improve - compared to my current 4K IPS LG - is the amount of backlight bleed... I mean, according to many people who saw my monitor in person, I've been extremely lucky, but I must say it became just a little bit annoying, in months of usage, especially with the OSSC (due to the fact you always play with thick black borders, so in pitch black conditions it can get distracting).

By any chance, did you try any of the following VA panels?

- Asus VN279QLB
- Benq GW2760HS
- BenQ RL2755HM

[Xyga]

Yeah but there's always 'that guy' with an old monitor saying things are different with it.
Of course they are! ^^ Common panels, parts, connectivity, popular standards etc have changed, many, many times over to the point an about 5~6 years old monitor can be radically different in terms of performance and compatibility compared to a seemingly similar one of today, and a an even older even more so, like night and day.
Never use old monitors knowledge as a reference for seeking current products, or you're up for way too many surprises, likely quite bad ones.

Anyway for VAs I keep my fingers crossed for the U32H850 to end up good, although I'm afraid it will be quite expensive.


@Thomago: leaking backlights are such a shame I even consider the issue a real market scandal, it's manufacturers giving the finger to quality control and customers as a whole.

Just out of curiosity: would 1440p be a better choice, in terms of chances to get something that doesn't mess around with the IQ too much?

As always there's very little means to be sure before buying, as common reviews are massively lacking in that area.

[Thomago]

By any chance, did you try any of the following VA panels?

- Asus VN279QLB
- Benq GW2760HS
- BenQ RL2755HM

Nope, non of them. Why?

- The Asus VN279QLB can't do 50 Hz according to prad.de; also, it's very old and, at the same time, unusually expensive (it costs €300 and doesn't even include a digital signal cable!).
- Judging from its manual, the Benq GW2760HS has the same aspect ratio control problems my iiyama has (I wouldn't be surprised if it had the same panel).
- The BenQ RL2755HM has a TN panel. I won't even consider that.

[Xyga]

The first two are among the first good AMVA+ FHD monitors.

The ASUS fared good, there was a guy who used it with an XRGB2 with excellent results. It used PWM for dimming although at an about 2000Hz rate iirc so no big deal. Very controllable overdrive (like 6 or 8 steps)
The BenQ was one of their early AMVA+, good, using direct current, but slightly less responsive overall with less effective overdrive. The slightly older but revised 'HM' version was more responsive.

[Galdelico]

Nope, non of them. Why?

- The Asus VN279QLB can't do 50 Hz according to prad.de; also, it's very old and, at the same time, unusually expensive (it costs €300 and doesn't even include a digital signal cable!).
- Judging from its manual, the Benq GW2760HS has the same aspect ratio control problems my iiyama has (I wouldn't be surprised if it had the same panel).
- The BenQ RL2755HM has a TN panel. I won't even consider that.

Wops. Nevermind then, and thanks for the clarification.
I thought to mention them because - once again - I've been pointed at those models recently, but didn't have the chance to research on them yet. Also, I thought both BenQs were VA, my bad. ^^;

Yeah but there's always 'that guy' with an old monitor saying things are different with it.
Of course they are! ^^ Common panels, parts, connectivity, popular standards etc have changed, many, many times over to the point an about 5~6 years old monitor can be radically different in terms of performance and compatibility compared to a seemingly similar one of today, and a an even older even more so, like night and day.
Never use old monitors knowledge as a reference for seeking current products, or you're up for way too many surprises, likely quite bad ones.

Yeah, that's the case. I just thought to mention it as a fact, that's all. And btw, this is the monitor: http://www1.la.dell.com/vc/en/corp/peri ... wfp&s=corp

[Xyga]

And btw, this is the monitor: http://www1.la.dell.com/vc/en/corp/peri ... wfp&s=corp

Those older desktop/pro-oriented monitors were great, although considerably slower than today's, the flexibility and controls were several times better.
I still keep my Belinea 2080 S2 for that reason, it's slow and the picture quality isn't up to that of current VAs, but its 'willingness' to just work when I want to try whatever is bliss.

[Xer Xian]

Has anyone managed to increase compatibility for 4x240p/2x480p by tweaking the adv.timing settings? I tried with a reduced vertical backporch (as Marqs suggested a few pages back) but didn't have any luck. I'm especially concerned with DVDOs machines - I can't take the craptastic 480p scaling, so I was hoping to linedouble all native 480p material before feeding it to the VP50. Heck, due to how nicely the VP50 deinterlaces the improvement of going with progressive scan is almost too little to justify the effort (thinking about the GC especially but the DC with its VGA boxes is a close second).

I know many here let the display handle 480p scaling but that's not an option for me (I'll probably have to capture 480p material in the future and need to upscale it to 1080p first, not by post-processing).

[headlesshobbs]

I think this should be possible by this point.

http://raster.effect.free.fr/tv/photos_ ... c_02c2.jpg

I've had luck replicating this in mame awhile back by blanking out every other vertical pixel. x4, x5 already shows you can do this.

Does anyone have a 720p display? I'm wondering if this has a similar effect?

[Guspaz]

We're at the point now where each pixel from a traditional 240p console (256x240) would be represented by roughly 101 pixels on a 4K display. That's a lot of pixels to simulate the sub-pixel structure.

[Jademalo]

We're at the point now where each pixel from a traditional 240p console (256x240) would be represented by roughly 101 pixels on a 4K display. That's a lot of pixels to simulate the sub-pixel structure.

How realistic would it be to make a post process filter for something like after effects that takes an x2/x3/x4 captured video with hard edged pixels and outputs a 4k video with simulated sub-pixel structure?
And on a step up from that, how realistic would it be to make a very simple HDMI to HDMI box that takes an x2/x3/x4 input and spits out the simulated sub-pixel 4k thing in real time?

I feel like the best way to do something like this would be to have it as a post processor device and keep it entirely digital, rather than making it an ADC+scaler as well. Adding this functionality into a scaler would take a ton of resources and jack up the price, and on the opposite side adding scaler functionality into something like this would do the same.
Would it be better to feed it an x4 scaled image, then have it generate a 256x240 signal to work from, or would it be better to feed it essentially raw 240p passthrough and then have it do all the scaling?

I'd totally buy a device dedicated to taking x2/x3/x4 scaled digital signals and pumping out a 4k simulated CRT.

[Xyga]

I'd totally buy a device dedicated to taking x2/x3/x4 scaled digital signals and pumping out a 4k simulated CRT.

Well, you know, a computer with emulators...

[Jademalo]

I'd totally buy a device dedicated to taking x2/x3/x4 scaled digital signals and pumping out a 4k simulated CRT.

Well, you know, a computer with emulators...

Yeah but that's no fun =p

[Monogamous]

Hi,
Is it possible to use a 75ohm CSYNC signal on the AV3 input? I was hoping to connect a gscartsw Lite with "Sync Regeneration" enabled.

[Harrumph]

No
http://junkerhq.net/xrgb/index.php?titl ... _.28VGA.29

[Monogamous]

No
http://junkerhq.net/xrgb/index.php?titl ... _.28VGA.29

What happens if you do?

[marqs]

Hi,
Is it possible to use a 75ohm CSYNC signal on the AV3 input? I was hoping to connect a gscartsw Lite with "Sync Regeneration" enabled.

Depends on the driving circuit. If it's a real ~1V transistor driver with 75ohm source impedance, then it won't work. If it's a 3.3V/5V IC driving the sync line with higher source impedance, then it should work fine.