1080p screen: 4x, 5x, fill, or 720p?

[shmupsrocks]

I think the options for scaling a 320p signal for a 1080p screen are 4x, 5x, vertical screen fill without integer scaling, or 3x to 720p. I found that 4x was too small, 5x cut off about 40 lines, and filling the screen vertically caused scanlines to look uneven. I thought 3x into 720p was the best with the screen almost filled vertically, integer scaling, and scanlines that look even. What do you do?

I thought 720p might be very slightly higher input lag but it could be my imagination.

Why doesn't scaling to 720p for a 1080p screen result in uneven scanlines since the TV has to scale from 720p to 1080p?

[Konsolkongen]

720p for sure, for the reasons you mention

TVs scale with interpolation, meaning that they apply some blur to the image. On a decent 1080p set this can be done well enough that the image still remains reasonably sharp, but still keep pretty uniform scanlines.

[shmupsrocks]

Which makes me wonder why a TV can do it (scale up non-integer and keep the scanlines even) but the Mega Sg can't.

[kamiboy]

Meh, I hate the fact that retro hardware scalers are stuck 10+ years in the past with 1080p resolutions when most of the world has long moved on to 4K. For year I've been hearing the excuse that fpga solutions are not fast or cheap enough to support 4K yet. Well, when are they going to be? I am willing to pay a pretty hefty premium for retro hardware scalers that can output a modern HDMI 2.1 signal complete with XXXp to 4k scalers with not just even scanlines, but also more modern CRT emulations possible with higher resolutions, such as shadow mask etc. and take advantage of VRR to avoid weird non standard refresh rate issues.

Analogue should get on this as soon as possible. They already make and sell premium retro hardwre, and have one external scaler. Hope in the future they will put for sale a 4K scalers for their systems.

[Josh128]

You said 320p resolution. Do you mean 240p? What exactly are you trying to scale?

If you scale 240p to 3X, thats 720p, but that will only fill about 2/3 of a 1080p screen when integer scaled. Thats not a good option at all.

Normally, you would use 4x for 960p, which would integer scale but leave 60 1080p lines of black at the top and the bottom of the image. If you scale to 5X, which is my preference on my 1080p screens, you will fill the screen top to bottom but will lose 60 1080p lines of the image at the top and the bottom.

[jamisonia]

5x for console games. These games were made with overscan in mind anyway. Rarely anything of consequence is cut off, and often ugly things are cut off anyway.

[ldeveraux]

Meh, I hate the fact that retro hardware scalers are stuck 10+ years in the past with 1080p resolutions when most of the world has long moved on to 4K.

But why would you need a retro hardware scaler to scale retro game content to 4k?

[orange808]

4k? Well, good news: the OSSC Pro will be open source. Port it to a more powerful board and go crazy. I bet marqs would even answer a few questions for you along the way. Who knows? Maybe a 4k DIY or official premium option will arrive later--after the firmware matures.

[tongshadow]

1080p>4k scaling is fine by what I've seen, specially for 2D sprite games. It's not much of a problem as 720p>1080p or 1080p>1440p.

[bobrocks95]

Meh, I hate the fact that retro hardware scalers are stuck 10+ years in the past with 1080p resolutions when most of the world has long moved on to 4K. For year I've been hearing the excuse that fpga solutions are not fast or cheap enough to support 4K yet. Well, when are they going to be? I am willing to pay a pretty hefty premium for retro hardware scalers that can output a modern HDMI 2.1 signal complete with XXXp to 4k scalers with not just even scanlines, but also more modern CRT emulations possible with higher resolutions, such as shadow mask etc. and take advantage of VRR to avoid weird non standard refresh rate issues.

Analogue should get on this as soon as possible. They already make and sell premium retro hardwre, and have one external scaler. Hope in the future they will put for sale a 4K scalers for their systems.

I believe even access to a dev board for a 4K capable chip was tens of thousands marqs said. HDMI 2.0+ features are all baked into custom ICs, so you can't buy a standard transmitter chip that does more than 1.4. Could be off, but there was a good reason it wasn't considered. We're up to 1440p anyways, which is quite good looking... These are 240p titles after all, though the argument for better scanline filters makes sense.

Also the Steam hardware survey shows 67% of PC players still using 1080p, so it's hardly 10+ years outdated.

[kamiboy]

I assume steam players play their games on gaming monitors where resolution is a secondary concern to refresh rate and other stuff PC gamers have always been preoccupied with. I imagine a good portion of the general public have a 4K TV in their living room though. Maybe FPGA is not the right approach for designing a scaler these days. If it is not up to snuff other more traditional CPU based solutions could be considered. Hell, maybe future generation raspberry products could be fast enough to do low latency 4K scaling.

As for why 4K? Because I don't want my TV to have to scale any retro stuff. The scaler in TV's are designed for movie and TV content, not retro pixel graphics. I have analogue products that I bought for some times using on my 4K OLED because it is more convenient than my CRT based setups. However, I find that no matter what setting I use the games look garish on my TV, and I just resort back to using a CRT. I am fairly sure the core of the problem is dual scaling. Any retro device connected to my TV should just output a 4k signal, taking quirks of TV scalers out of the equation.

I was expecting 4K to be standard by now. I am still certain it will become standard in the future, it is just taking too long.

[Kez]

I'm not sure what you mean by garish? It's worth bearing in mind that even an unscaled image will still have some processing performed on it by the TV. In my experience, most TVs scale sharp 1080p to 4K pretty nicely and any blurring at boundaries is not noticeable at a distance.

You might find that your problems are not resolved by a 4K signal, perhaps there is an issue with the way your TV is configured (colours, post processing, sharpness) that is more noticeable on the upscaled low-res content of old games.

For my money, 1080p is plenty for the "sharp pixel" look and moving beyond gives diminishing returns. Where modern displays really fall short vs CRTs is motion clarity, and while BFI goes a long way it is not without compromise. Still I would prefer to see 120hz 1080p with BFI on upcoming scalers than 4K resolution (although I would assume any scaler capable of 4K would also be capable of that), although moving into 4K and beyond definitely presents some really interesting opportunities for advancing video filters.

[shmupsrocks]

You said 320p resolution. Do you mean 240p?

Yes.

If you scale 240p to 3X, thats 720p, but that will only fill about 2/3 of a 1080p screen when integer scaled.

Yeah but I don't think most (any?) 1080p TVs will display a 720p signal without upscaling it to 1080p so in practice the screen is almost filled. The TV has to interpolate going from 720 to 1080 of course but the scanlines still look even for reasons I don't understand.

For 4K screens you could have the scaler do 3x from 240 to 720 and the TV will do another even 3x from 720 to 2160 (4K).

[bobrocks95]

Can't find the comparison image I was looking for, could have sworn it was retrorgb, but it was the usual LttP screenshot showing each OSSC line multiply mode. 2x to 3x- big improvement. 3x to 4x- ever so slight improvement. 4x to 5x- essentially not visible. It's definitely diminishing returns.

What kind of TV do you have kamiboy that's upscaling so poorly? Anything 1080p and above looks great on my LG OLED.

[Josh128]

Yeah but I don't think most (any?) 1080p TVs will display a 720p signal without upscaling it to 1080p so in practice the screen is almost filled. The TV has to interpolate going from 720 to 1080 of course but the scanlines still look even for reasons I don't understand.

None of the 1080p sets I have do what you are saying. The only way thats possible is if your 1080p set scales the image to 1440p and crops off a huge part of the image, which I'd bet good money that is not whats happening.
If you dont integer scale the signal, you will have shimmer/uneven artifacts in certain colors/motion in your scanlined image if you examine closely. Mike has made it so it does a pretty good job of masking the issue of uneven scaling, but a discerning eye can easily tell when its in motion. Now, if you are using a 768p set, thats a different story. The 720p 3X mode looks great when centered in a 768p set. Again though, its going to have small black bars of 24 pixels high on the top and the bottom.

For 4K screens you could have the scaler do 3x from 240 to 720 and the TV will do another even 3x from 720 to 2160 (4K).

Yes, that works perfectly, as it should. 720p will scale evenly into 4K.

[NewSchoolBoxer]

Also the Steam hardware survey shows 67% of PC players still using 1080p, so it's hardly 10+ years outdated.

I play in 1080p too but it's on a 165 Hz gaming monitor with g-sync and 1 ms response time. Not worth trading that for 4K. Same idea that kamiboy had.

I agree with your sentiment though that most people are behind the times / new technology is slow to be adopted. Always worked that way. Black & White televisions outsold Color sets for years after they came out. I didn't have anything that took HDMI until I bought my 1080p Samsung television in 2009.

...Maybe FPGA is not the right approach for designing a scaler these days. If it is not up to snuff other more traditional CPU based solutions could be considered. Hell, maybe future generation raspberry products could be fast enough to do low latency 4K scaling.

As for why 4K? Because I don't want my TV to have to scale any retro stuff. The scaler in TV's are designed for movie and TV content, not retro pixel graphics.

Yeah I don't think FPGA is the right approach here. I'm confident that you can find one fast enough to do the job but the question becomes at what price point?

To upscale 1080p to 4K, you wouldn't need more than 4 threads to fix the same pixel in all 4 places on the screen for max parallelization. The thing with FPGAs is they are superior for parallelization but they are expensive. I can buy a $15 chip that upscales 480i analog video to 1080p digital off a +5V power supply. The GBS-8200 hack to downscale uses ESP8266 microprocessor that for less than $10 comes fully working on assembled board (with WiFi). The native upscaler chip is a Chinese Tvia TrueView 5725 that is likely also very cheap.

Interesting comparison is OSSC and Retrotink 5x Pro use FPGAs and the 5x Pro is Retrotink's first product to use one. The actual 5X Pro's website description states it uses the FPGA for motion adaptive deinterlacing. Been done long ago in processor software, but I assume the development and testing and interacting with all the input and outputs in the < 1 frame of lag time required is easier to do, on a single person project, with an FPGA.

[TooBeaucoup]

Meh, I hate the fact that retro hardware scalers are stuck 10+ years in the past with 1080p resolutions when most of the world has long moved on to 4K.

But why would you need a retro hardware scaler to scale retro game content to 4k?

This. Technically speaking, you would be getting a sharper image with a 4k scaler. But, to the human eye, we're probably talking a 1% sharpness increase that you'd never even notice, unless you game on a 100+ inch screen or sit 12 inches away from your 40 inch screen. These pre-2000s consoles will benefit very little from a 4k scaler with the type of visuals they put out, especially when you consider scalers like the Tink5X can do 1200p and 1440p. Bumping these older consoles a little further to 4k scaling will make very little difference in the grand scheme of things, especially considering what the price difference would be for a 4k FPGA. Don't get me wrong, if a 4k FPGA were close to the same price, obviously, I'd prefer it, but the price difference is astronomical at this point and even worse than usual thanks to the chip shortages. At 1080p and especially 1200p-1440p, we're really hitting diminishing returns for these older consoles when going to 4k.

[nissling]

Main benefit of 9-10X scale of 240p would be the possibility to get better scanlines and other post effects. But you can get pixel perfection at 1080p with currently available devices and have it scaled to 3840x2160 with no real loss in sharpness. Scaling is done all the time, everywhere. The issue is nowhere near as bad as some people here blindly think.

[Josh128]

A 9-10x scale would be most useful for:

1.) Scaling 720p to 3X using 2/1 game to scanline ratio @4K for perfect, native looking 720p.

2.) Scaling 1080p to 2X w/ scanlines. Would be pretty dark, but look better than straight 2X with no scanlines.

2.) Scaling 480p to 1920p/2400p for use with scanlines @4K, though Im not sure how much better this would look than scaling to 1440p and stretching that to 4K via the TV. It would allow for more customizable/polyphase scanlines at the very least.

That said, none of these are super high on my wish list. The current 5X paired with a 4K TV does really well.

[Konsolkongen]

A 9-10x scale would be most useful for:

...
2.) Scaling 1080p to 2X w/ scanlines. Would be pretty dark, but look better than straight 2X with no scanlines.
...

Why would you want scanlines on a 1080p source?

[Guspaz]

With modern poly scalers like the RT5X, there's no need to align scanlines to output resolution, just output it at the highest resolution the display supports to get the best looking scanlines. And for 4K displays/TVs, integer scaling is pointless/moot since with extremely few exceptions the TV will not be doing a nearest neighbour scale from 1080p to 2160p, so the path to the sharpest/crispest pixels is again to just use the highest output resolution the display supports.

With a poly scaler on 1080p, I personally don't see the point in integer scaling (it's very crisp/sharp anyhow), but I do see the benefit of using 5x scales for many games where the system normally outputs partial frame content (like the 224p output of many consoles) or where some games themselves are quite letterboxed (extreme examples are things like Starfox on SNES).

[Josh128]

Why would you want scanlines on a 1080p source?

Same reason I want them on a 480p source--it looks native. Its always better to be able to do 3X res for scanlines if possible for brightness, but thats not happening with 1080p. I hate the look of interpolated upscaling with a passion. Of course, the higher source res you go, the less problematic it is, but I would at least like the option for 1080p.

With modern poly scalers like the RT5X, there's no need to align scanlines to output resolution, just output it at the highest resolution the display supports to get the best looking scanlines.

The polyphase scaling does very well with non-integer scaling, I agree. BUT...I can tell on certain colors (blue seems to show it well) and motion a very slight shimmer or slight waves of light/dark when the source is not integer scaled. Its so subtle that many might never notice it, but once you see it, its one of those things. Its the reason I go with integer scaled 1080p Over for 240p sources.

[neorichieb1971]

I use 720p with scanlines and it gives me the look I want.

Its better to have the mentality of "good enough" vs some sort of holy grail for everything. Once upon a time I went for the holy grail on everything and spent a fortune on stuff and never played anything because I was faffing around with settings forever and a day.

some things like the neo geo mini arcade machine fall short of expectations, but the Analogue stuff hit home for me.

[kamiboy]

Can't find the comparison image I was looking for, could have sworn it was retrorgb, but it was the usual LttP screenshot showing each OSSC line multiply mode. 2x to 3x- big improvement. 3x to 4x- ever so slight improvement. 4x to 5x- essentially not visible. It's definitely diminishing returns.

What kind of TV do you have kamiboy that's upscaling so poorly? Anything 1080p and above looks great on my LG OLED.

I have a 77" LG OLED GX. The scaling on it is not poor, perfectly adequate for film content, just not pleasing to my eyes when it comes to 720p pixel graphics with scanlines. I can't stand the boxy pixel look when it comes to low res sprites, even though indie games have somehow managed to retcon those aesthetics as the default look of pixel graphics for generations that didn't grow up playing 240p games on CRT's. The retro look I want is one as close in terms of pleasing aesthetics to what I get on my BVM A20, or hell, even one of my lowfi B&O CRT TV's, or an old Arcade monitor.

I understand most people don't have the problem with pixel graphics that I have. But I have always, always found pixel graphics scaled on fixed resolution displays to look excruciatingly garish, to be point of being distracting. I'd love to just ditch all the mess of wires, old hardware and bulky CRT's in my room and just make my OLED TV the focus of all generations of gaming. But anything before PS3 era I just cannot stand to look at on a fixed pixel display. Hell, even PS3 games look better on the BVM via 720p component.

When it comes to pixel graphics the approach so far has been one of two. Either a blurry mess, or razor sharp defined square pixel blocks, aka the indie pixel art game look. I hate both, though the blurry mess more. I think 4K and above resolutions have enough pixels to play around with to allow for better emulation of the CRT look than the traditional approaches so far.

While I have yet to get my hand on an Analogue pocket, mine will ship Q4 2022, from what I have seen their approach to emulating the exact look of old LCD technologies used in he DMG gameboy and Gameboy Advanced displays is the kind of next level scaling approach I am hoping for on 8 and 16 bit home consoles.

I know these approaches already exist, and can scale to 4K resolutions via emulation on PC's. But I have a similar distaste for emulation gaming. FPGA is close and hassle free enough where I am comfortable ditching the old original hardware and its bag of headaches for another, but so far only on CRT's. Better 4K scaling options is what is missing before I can ditch CRT's and leave legacy hardware behind for good.