GBS 8200 + GBS Control: Hands-On with the Downscale Feature [English Version]
[Versão em português deste artigo aqui.]
By now, the retro gaming community is no stranger to upscalers and line multipliers such as the Framemeister, OSSC, RetroTINK-2X and the GBS 8200 itself, which we are going to cover in this article. These are devices generally used to upscale, that is, increase the resolution of old games to display them on modern high resolution screens. However, a lesser known facet of the retro scene is that of downscalers, devices whose purpose is to actually decrease the resolution of a video signal.
It might be counter-intuitive, but a lower resolution is desirable in some specific scenarios (check a list of possibilities further below), and devices that perform this task are coveted by a niche of enthusiasts. Some of them are the Extron Emotia line of video processors, which disappeared from the market and, consequently, now reach exorbitant prices — while such a unit could be found for $ 50 to $ 150 on eBay a few years ago, now the models capable of generating a 240p signal (Emotia, Emotia Plus, Super Emotia and Super Emotia GX) sell for $ 400+ when they pop up.
Fudoh, a reference in the community for his articles on video processors, published a detailed report on downscalers complete with brands, models, usage examples and comparisons. The article was last updated in 2013, but little has changed in this segment until recently. Announced in January 2020, the OSSC Pro is expected to include the downscale function among its features, but there is still no information on when the long-awaited successor to the OSSC will hit the market — and at what price …
But the most exciting recent development in the downscale area comes from GBS Control , a custom firmware created by Robert Neumann, known in the community as Rama. This firmware turns the GBS 82XX line, originally quite problematic but relatively inexpensive video processors, into versatile and efficient devices — Bob from RetroRGB recently published an excellent video testing the GBS Control. But the aforementioned revolutionary feature that was recently added is the coveted downscale capability! And “revolutionary” in this case is not a hyperbole, as this function in a low-cost device makes the disputed hundreds of dollars video processors obsolete.
It seems hard to believe, but the feature really works, and we did some preliminary tests to put the device through its paces.
Usage Examples
Before we get down to the nitty-gritty, let’s check examples of why achieving a lower resolution can be useful. The root of the problem is in technology transitions and how information from old standards is handled on later devices.
Consoles and arcades until the mid-90s operated with a 240p video signal, a progressive variant of the 15kHz signal. With advancements in processing power, consoles and some arcade games were suddenly able to output “high resolution” at 480i, which is still a 15kHz signal, but with an interlaced image — each vertical scan cycle of the CRT draws only half of the lines, first the odds, then the evens, and so on and so forth (each vertical scan cycle in this case forms a field). The Saturn/PS1/N64 generation was the first to have games with this resolution on a regular basis, and in the following generation 480i became the standard, while games with 480p resolution support (480 lines of progressive vertical resolution, with each vertical scan cycle drawing a complete frame) became a reality.
The problem is the mismatch when re-releases of old games that were originally created in 240p reached consoles that output in 480i or 480p. At the time, it might have been the obvious solution, and most players certainly didn’t even notice, but most classic games released for PS2/GameCube/Xbox use 480i resolution by default and do not have a 240p output option, which generates two problems: 1) on a 15kHz CRT TV, the image flickers, and 2) to be displayed on modern flat screens, these images need to be “deinterlaced”, a complex process that can hurt the image and ruin some visual effects of the content that was originally progressive, then was converted to interlaced, and then made progressive again. In some cases, these classic games on these platforms also support 480p progressive mode, but this resolution: 1) is not supported by TVs and CRT monitors that only accept 15kHz; 2) on CRT screens that accept 480p, scanlines are not as defined as they were originally at 240p on a 15kHz screen; 3) on modern TVs, at least, this 480p is within the expected signal standards, but 4) with dedicated upscalers and line multipliers, a 480p signal has different characteristics than a 240p image, so you may not get the same results or have access to the same features as a native 240p signal.
Therefore, downscaling the resolution back to 240p is a way to try and restore the original characteristics of games that had that resolution to begin with, and were then adapted to higher resolutions. But it’s not limited to that purpose only. Some usage examples:
- Run old games re-released on consoles such as PS2/GC/Xbox in 480i without flicker on 15kHz CRT TVs/monitors using the original resolution of 240p.
- Being able to run old games re-released on consoles such as PS2/GC/Xbox with 480p support on 15kHz CRT TVs/monitors using the original 240p resolution.
- For those who have a Naomi arcade board, there is also the case of Street Fighter Zero 3 Upper, an update to the CPS2 game with the addition of extra characters from the console versions, but which only runs in 480i or 480p because of platform specifications. The downscale should allow you to play it in 240p, just as it was in CPS2.
- Run old games re-released for PS3 and Xbox 360 by using component output and resolution set to 480p on 15kHz CRT TVs/monitors using the original resolution of 240p. (Pro tip: the Xbox 360 has incredible ports of arcade shmups that have not been converted to any other platform.) It is possible to display the image on a CRT with a downscaler, but the actual quality will depend on a number of factors affecting the port, such as whether or not the game have smoothing filters applied and, more importantly, if the image is stretched on the vertical axis with a non-integer method.
- Run games created in 480i/480p with mixed assets, i.e. with some elements designed in “high resolution” (like backgrounds and HUD) combined with elements recycled from previous games and that were originally in 240p (such as sprites). The downscale, in this case, homogenizes the entire image in 240p. Some examples: Marvel vs. Capcom 2, Capcom vs. SNK 1/2, Capcom Fighting Evolution, The King of Fighters XI, Neo Geo Battle Coliseum, etc. The quality will also depend on whether smoothing filters were applied to low-resolution assets (if possible, choose Sharp or a similar option to not smooth the pixels). It is worth mentioning that details of the elements drawn natively in higher resolution will be lost, something that can make reading small text hard or nearly impossible.
- Running modern games designed in pixel art with an 8/16-bit aesthetic on CRT and with the resolution they intended to emulate. (Pro tip: the Wii has the ReBirth series from Konami, which get the perfect treatment with this 240p downscale.) Again, the results will depend on whether the pixel grid matches the 240p scanlines, and there is always the question of how to fit a 16:9 image on a 4:3 screen.
- Run modern games on a 15kHz TV/monitor at 240p just because. In this case, for consoles such as PS4/Xbox One/Switch or even a PC, it would be necessary to set the output to 480p resolution (GBS Control does not downscale 720p or higher) and have an HDMI to component or VGA converter to connect to the GBS. PS3 and Xbox 360 can use component cable. It should be stressed again that this results in loss of visual information, no to mention the problem with small text readability.
- Run emulators on the PC, Raspberry Pi or other devices outputting HDMI or VGA at 480p and converting to 240p for use on a 15kHz CRT.
- Send a 240p signal to another scaler/line multiplier to upscale from a more suitable source when dealing with games that were originally in 240p. This avoids the problems of deinterlacing for 240p games re-released at 480i, and allows for a more authentic result for 240p games with 480p support. It is possible to connect the GBS to the Framemeister using a VGA to HDMI or a VGA to component cable. If the OSSC is your device of choice, you can hook up the GBS to it straight via VGA cable or use a VGA to component cable instead. Of course, the latency will add up in the device chain, but let’s do some math: according to Bob’s lag test of retro scalers, the Framemeister has 1 frame of lag when handling progressive signals, and 2 frames with interlaced signals. The GBS Control downscales from 480p to 240p in 8 milliseconds (half a frame of lag, “the fastest downscaler available”, according to Bob) and deinterlaces a 480i signal with motion adaptive algorithm in up to 1 frame (in line with our own shoddier lag test measured with 240 fps slow motion video from a smartphone camera). So, if the GBS Control downscales from 480i to 240p with 1 frame of lag and sends that newly-progressive signal to the Framemeister, and if the Framemeister treats progressive signals with 1 frame of lag, the sum of the devices in this scenario would be the same 2 frames that the Framemeister alone takes to deinterlace a 480i signal, but with potentially more interesting results (more details when we get to the actual tests further in this article).
What is Necessary
- A GBS 8200 board, which is the basis of the project;
- An ESP8266 microcontroller board, which takes control of the upscaler and allows configuration over wi-fi via a web interface;
- The latest version of the GBS Control custom firmware;
- Wires, equipment and skills for actually installing the GBS Control on a GBS 8200 board (or buy a fully assembled kit — suggested listing below if you live in Brazil);
- Wi-Fi network to operate the GBS via web interface;
- Input devices and cables: the GBS 8200 accepts YPbPr signal via component input, RGBHV via DE-15 connector (VGA) or RGBS via DE-15 connector (VGA) with the necessary modifications (link below to a kit with a custom sub-board that adds a hassle-free RGB SCART connector). It is also possible to connect a source via HDMI cable using an HDMI to VGA or component (YPbPr) converter;
- An actual screen to output to, as well as cables matching the needs of your setup: the GBS 8200 outputs via a DE-15 (VGA) connector and sends an RGBHV signal by default, or, with the GBS Control firmware, it optionally can send a YPbPr signal via the same DE-15 connector (it needs a VGA to YPbPr/component cable to use this option) (this YPbPr signal output from the GBS requires a hardware modification in order to output the correct signal level). The 15kHz CRT monitor or TV must accept a YPbPr/component connection. To connect to a TV or device via HDMI, you need to use a VGA to HDMI converter.
If you live in Brazil (or are willing to import), there’s an interesting assembled kit from GamesCare that includes the properly modified GBS 8200 board, an exclusive sub-board with sync stripper, additional SCART RGB input, SCART/VGA input selector with adequate signal level, in addition to a quality PSU and a neat acrylic case.
Test Setup
For this downscale test, we used the following setup:
- Consoles: PlayStation 2/Wii outputting YPbPr via component cable, PS3 configured to output YPbPr in 480p via component cable;
- Two professional CRT monitors:
- Sony PVM-14L5, a multiformat monitor [accepts 15kHz (240p/480i), 31kHz (480p) and above] receiving YPbPr signal in 480i/480p resolution straight from the consoles (passing through the component matrix);
- Sony BVM-20F1U a 15kHz monitor (only accepts 240p/480i) receiving the image downscaled to 240p resolution from the GBS in YPbPr via VGA to component cable; - C2G 6x2 Component Matrix to switch component connections and provide two simultaneous component outputs, one straight to the PVM-14L5 monitor at 480i/480p, and the other to the GBS 8200 + GBS Control, which processes the signal and downscales it to 240p before sending it to the BVM-20F1U monitor via VGA to component cable;
- GBS kit from GamesCare with a VGA to component cable on the output side, with GBS Control configured to output a YPbPr signal;
- Photos and videos shot with an iPhone 8 Plus camera pointed at the CRT screens, with an app to set the shutter speed to 1/60. Videos recorded at 1080p60;
- StarTech.com USB 3.0 Video Capture Device to capture some of the test videos. On such instances, the GBS outputs YPbPr at 240p to the Framemeister, which upscales the image to 1080p and sends the processed result to the capture card via HDMI.
It is important to note that these are preliminary tests of only a few scenarios — there are still several other usage examples to explore. Both CRT monitors have their geometry adjusted for different purposes, so there is a slight difference in the aspect ratio. In addition, the YPbPr output option from the GBS Control was used, but this option requires one resistor to be changed on the GBS 8200 board to output correct signal level; this hardware mod had not been implemented on our unit yet, so the 240p downscaled image on the BVM-20F1U monitor is a little washed out compared to the PVM-14L5, which receives the YPbPr signal straight from the consoles in our test setup. Finally, we need to emphasize that the GBS with GBS Control only downscales images from 480i and 480p sources, so the feature is not compatible with 720p resolution and above. Furthermore, seems like GBS Control have a hard time downscaling RGBHV signals at the moment, but we only tested it with YPbPr image source.
The Tests
Downscaling images with the GBS Control is relatively simple: once you have your setup ready and have configured the GBS on your wi-fi network, just access the web interface from a device with a browser connected to the same network, go to the Presets tab and choose the option “15kHz Scale Down”. The 480i/480p input signal will be downscaled to 240p and sent to the output (please notice that 720p input resolution or higher is not compatible with this feature of the GBS Control). By default, GBS Control outputs RGBHV via the DE-15 connector, but if you are going to use a VGA to component cable, remember to go to the Preferences tab and switch to a YPbPr output in the option “RGBHV/Component Toggle” (just remember that the GBS 8200 needs a hardware modification in order to send a YPbPr signal at the correct level). If the input signal is 480i, i.e. an interlaced image, it is also possible to choose the deinterlacing method to be used in the Preferences tab, under the Deinterlace Method section: 1) Bob: it takes each interlaced field and simply uses only the drawn lines to form complete progressive frames in 240p; it does not add any lag, but it causes flickering (the image seems to bob up and down alternately, hence the name); 2) Motion Adaptive: has no flicker at all, but adds 1 frame of lag and causes some artifacts on moving objects.
Downscaling 480i games with 240p assets
Downscaling content from 480i sources to 240p has an additional challenge, as simply reducing the resolution of the image is not enough, but it is also necessary to deinterlace the signal. This creates complications, as it is not just a matter of combining the alternating lines of the odd and even fields to form a complete frame. See, with video games (and movies), there is movement from one field to the next, so subsequent fields represent different moments of the movement. With the Motion Adaptive method enabled, GBS Control deinterlaces the image by weaving together the fields on areas of the image that have not changed from one field to the next, and areas with movement are combined by interpolation, trying to avoid combing artifacts (when two fields at different times are weaved and form a “dented” object resembling a comb). In our tests, this motion adaptive deinterlace from 480i was quite impressive, but with a few caveats.
Examples of games originally created in 240p and later ported to other consoles using a 480i format include Street Fighter Alpha Anthology and SVC Chaos for PS2, among many others. In the video above, we tested SVC Chaos and compared how the downscaled result compared from 480i output versus the same game with 480p output (you can activate progressive mode holding X + Triangle during boot — only works with compatible games). In this test, in both cases the GBS outputs a downscaled 240p signal to the Framemeister via component, and from there the image is upscaled to 1080p and sent via HDMI to the capture card to record the result on video. Finally, we made a montage comparing results side by side.
What we learned, besides the fact that feeding the Framemeister with a real 240p signal in the case of assets created in 240p generates a much more pleasing image, is that GBS Control’s motion adaptive deinterlacing is quite impressive. Still areas of the image are very sharp, and moving areas won’t show combing artifacts at all. However, moving objects end up alternating between sharp and blurry frames, showing some difficulty of the algorithm in prioritizing fields of the interlaced source. This is more noticeable when the entire screen moves (as in the test starting at 1:43 in the video above), but even when only one sprite moves, it is possible to notice alternating blurry and sharp frames. In addition, the interpolation of fields has a curious side effect: objects that quickly change color between one field and another tends to confuse the algorithm, as can be seen in the power bar at the bottom of the screen in SVC Chaos, which normally quickly alternates between white and red in successive frames, which makes GBS Control’s motion adaptive algorithm mix the tones and generate a purple-ish color.
This phenomenon can be especially problematic for 30Hz shadows and other flashing elements that were used to simulate transparency in old games, such as when Mickey takes damage in Castle of Illusion on the Sega Genesis, or Sonic’s shield in Sonic the Hedgehog, also on the Genesis. It works like this: the object appears in one frame and disappears in the following frame, and so on and so forth, 60 times per second, giving the human eyes the illusion of transparency.
To test how GBS Control’s motion adaptive deinterlacing method handles this scenario, we used Artemio’s 240p Test Suite tool on the Wii via component output. We recorded the tool configured to output in 480i to test the deinterlacing of the GBS Control downscaler with both Bob and Motion Adaptive methods, and we also recorded the same test with 480p output to compare.
As you can see from the test with the 240p Test Suite, the downscale from the 480p signal, which does not need to deinterlace anything, keeps the characteristics of the 30Hz shadow (although it still seems like the shadow is interpolated with background colors), while the 480i signal poses challenges to the deinterlace algorithm of GBS Control. With the Bob method, the 30Hz shadow effect is preserved at almost all times, but the screen flickers. With the Motion Adaptive method, the shadow is interpolated with the background, with parts of it disappearing completely sometimes, and other times with its colors blending with those of the background — but free of any flickering.
In the same test above, we also used SVC Chaos for PS2 with 480i resolution with Arcade screen mode set on the Options menu. The default screen mode for this port is Normal, on which the fonts and HUD were redrawn in high resolution, and the game received real transparency on life bars and in some special effects, such as projectiles and shadows — because of this, shadows in this new screen mode do not blink to simulate transparency. With the Arcade screen mode, all of these elements are restored to their original form from the Neo Geo version, including 30Hz blinking shadows. Thus, we were able to test the deinterlacing of GBS Control in a real game scenario. And the result is consistent with the 240p Test Suite test: with the Motion Adaptive method, sometimes shadows from the characters disappear completely, and other times they are just a solid color; with the Bob method, shadows blink correctly (although, again, there still seems to be some interpolation in effect, as the shadows blend with the background as if they were really transparent) (as a bonus, with the Bob method the power bars on MAX blink just like in the original), but the whole screen flickers.
In the video, the results represent how it looks like on a modern flat TV when the deinterlaced 480i image is downscaled to 240p then scaled to 1080p by the Framemeister. On a 15kHz CRT, the result is consistent, anomalies on blinking objects and all, but it looked less noticeable to us because of the scanlines. With the Bob deinterlacing mode, though, the 240p image processed by GBS Control on a CRT monitor seemed to flicker much more than with a pure 480i signal.
Finally, another point to consider when you downscale 480i games with GBS Control is that in some cases the game appears to have a different field order than what the GBC Control deinterlacing algorithm expects, drawing a somewhat diffuse image. This problem does not affect SVC Chaos for PS2 in 480i, for example, but Street Fighter Alpha Anthology on PS2 downscaled from 480i looks somewhat blurry and has some jagged lines in the resulting 240p image, so this problem possibly depends on the game. Rama, the creator of GBS Control, commented on this issue on the Shmups forum and mentioned a possible solution, but there is still no news of an update since then. Perhaps the additions of an option to choose the field order for the deinterlacing algorithm would solve the problem? I don’t know. Anyway, Rama pointed out that 480i should be avoided if possible and that 480p is preferable for downscaling.
Downscaling 480p games with 240p assets
As the creator of the GBS Control himself recommended, 480p to 240p downscaling is quite stable and without major setbacks. As the source is progressive already, the algorithm does not need to deinterlace anything, since it is dealing with full frames. The result, however, also depends on the image that is sent from the console to the GBS.
For reference, here are some lists of games with support for 480p mode on 6th gen consoles:
- Dreamcast VGA Compatibility List & Guide
- List of PlayStation 2 games with alternative display modes
- List of Xbox games with alternate display modes
- List of GameCube games with alternate display modes
Only some of the games on these lists consist of titles that were originally 240p and were ported to these consoles at a higher resolution. For our article, we tested SVC Chaos and Street Fighter Alpha Anthology for PS2, both originally released on arcades at 240p and later ported to the console with 480p support. SVC Chaos turned out great, as you can also see on our videos embeded above. Street Fighter Alpha Anthology looked a little smooth, even though we made sure the smoothing filter was off in the game options. In this title, elements drawn in high resolution, such as the title screen of the collection and artworks in the game selection screen, were visibly jagged after the downscale when displayed on a flat TV through the Framemeister, which implies that the GBS Control downscale algorithm is really only discarding half of the lines, without applying any interpolation that could smooth the graphics — on the 15kHz CRT monitor, the displayed image was very good. With SVC Chaos, the 480p mode features perfectly shap pixels, which contributed to a pristine downscale, as if it were the original game in 240p.
Jumping one generation ahead, with the consoles of the Full HD era, Xbox 360 and PS3, there are also several re-releases of old games, and as these systems can be configured to output a 480p image via component cable, they are also easy to use with the GBS Control. However, with a new 1920x1080 canvas, developers now had more freedom to scale old games within these new and exciting dimensions, something that would create problems for modern screens (remember, we are talking about the second half of the 2000s and early 2010s, long before discussions about pixel perfect ratios, integer scaling, shimmering, pixel interpolation, etc. gained traction in the retro gaming community), with potentially disastrous repercussions for the crazy enthusiasts who would try to downscale these images to 15kHz CRT screens years later too. When a 240p game is irregularly scaled from its original vertical dimensions, that result in uneven pixel distribution, which will certainly compromise the result when trying to downscale (something that developers certainly didn’t anticipate, understandably). See, downscale is a process of eliminating visual information: half the lines of a 480p signal are discarded and the other half is preserved to compose a 240p signal. When the discarded information is redundant (as in 240p games that were upscaled by 2x with neared neighbor algorithm and had their pixels doubled to compose a sharp 480p image), the result is pristine. If the original vertical pixel distribution was messed with and the pixels are not evenly distributed anymore on the Y axis, it will surely result in a bad downscale, with potential loss of detail. Let’s look at the case of Ghosts ’n Goblins in the Capcom Arcade Cabinet collection on PS3. By default, the game runs in a window with non-integer scaling. In our test, outputing from PS3 in 480p, it is still possible to see the details on the CRT of the PVM-14L5 multiformat monitor, which receives the original signal in 480p, but on the BVM-20F1U screen, which receives the image downscaled by GBS Control to 240p, details are lost. Check how Arthur’s eye had the misfortune to fall on a line eliminated by the downscale:
Fortunately, the Capcom Arcade Cabinet collection offers image settings options, and very conveniently includes a pixel perfect setting. We simply toggle this option and… voilá!
Unfortunately, not all games offer screen scaling options. Two great candidates for downscale champions were Mega Man 9 and 10, created in the Full HD era inspired by the NES 8-bit aesthetic (before it was cool). Being able to display them in real 240p on a 15kHz CRT would be like finding the missing link between those ages. However, the way the game is displayed is not very conducive to downscaling. Apparently, the game was designed in 640x560 (judging from the original BMP promotion screens), which results in an aspect ratio of 8: 7, identical to the NES internal resolution, with a 2.5x scaling in relation to the resolution of the NES (256x244), and then the game screen was probably stretched arbitrarily to the screen resolution of each system and output format. In the case of the PS3 at 480p, either the vertical dimension doesn’t exactly fall on the 240p lines, or the vertical scaling of the content is uneven, or both. The fact is that the image resulting from the GBS Control downscale is somewhat blurred, as shown in the comparison below.
Other PS3 games that we tested and were good for downscaling for having screen settings adjustments include The Simpsons Arcade Game and Final Fight from the Final Fight Double Impact package.
And we should not forget that every PS3 runs PS1 games on disc (as long as they are from the same region), in addition to having PS1 Classics digital versions. When connecting a PS3 directly to a 15kHz CRT screen, the lowest possible resolution is 480i. However, with GBS Control, we have the option to set the PS3 to output 480p and downscale it perfectly to 240p to enjoy PS1 games in their native resolution on a CRT. Just don’t forget, as the fine folks from My Life in Gaming noted, that some disc games are sharper than their digital counterparts.
And then there is the case of games created in the Full HD era mimicking the 8/16-bit aesthetic. However, with these, the results also depends on luck. We tested Shovel Knight for PS3 downscaled from 480p to 240p on a 15kHz CRT monitor and no screen setting fiddling would make the pixels match scan lines correctly. It works, but there is that feeling of unfulfillment. Perhaps if you try the PC version with VGA/HDMI output set to 480p, and the PC having better control over screen dimensions would achieve the perfect setting for an impeccable 240p downscale? I don’t know. If anyone finds out, please let us know.
We had better luck with Scott Pilgrim vs. The World on PS3. The art of the game simulates pixels from old games, albeit with a strange uneven distribution. As a fortunate side effect, since the sprites and simulated “pixels” (actually designed with several smaller pixels within the console’s internal resolution) are quite large, the result of the downscale on a CRT is very convincing.
Finally, in this category of games created at higher resolution based on a 240p aesthetic, we have the ReBirth series from Konami for the Wii’s WiiWare service. They are new entries in famous franchises from the company that were developed by M2 to honor this legacy. Castlevania ReBirth, Gradius ReBirth and Contra ReBirth are like 16-bit sequences of these classics, but with visual effects that the original consoles could not generate. The problem is that, although they use 240p assets, these games only support 480i or 480p resolutions, and are relegated to never achieve that particular visual of old consoles on a CRT screen — at least not natively. But, GBS Control to the rescue! The 480p resolution is very convenient for this restoration work, and the downscaled 240p image makes this trio of games look like they always deserved on a 15kHz CRT!
Downscaling 480p games with mixed assets (240p/480p)
In the department of games created in high resolution, but directly recycling sprites from 240p games of the past, we have some classics like Marvel vs. Capcom 2, Capcom vs. SNK 1 and 2, The King of Fighters NeoWave and XI and Neo Geo Battle Coliseum, among others.
We tested Capcom Vs. SNK 2 from the PS2 Classics line on the PS3 at 480p (but it could very well be the original Xbox version, which also supports 480p; natively, the PS2 version unfortunately only supports 480i, just as the GameCube version; on Dreamcast, the game is compatible with VGA Box, but GBS Control is said to have a hard time handling a RGBHV signal for downscaling, so it would be necessary to use a Toro Box from Beharbros or GamesCare’s VGA Box to output 480p in VGA mode over SCART in RGBS). As expected, the downscale to 240p on a 15kHz CRT monitor works well. However, there’s something to consider: although details of the low-resolution sprites are not lost in this process, backgrounds and other elements of the game are drawn at a higher resolution, so visual information is lost on these elements. A fair exchange, if you ask me.
Downscaling 480p games with high resolution assets
To close off our test, let’s throw logic out the window a bit and include modern games designed entirely in modern high resolutions. Can you downscale them? Yes. Should you? Probably not. Do you want to? Surely!
As we have already pointed out, downscale is a process of eliminating visual information, and in this case we are talking about non-redundant information (each resolution line contains unique information), so eliminating lines by downscaling means losing details. Having in mind that GBS Control requires a 480i/p signal to downscale, then a game designed in 1080p will already have to be downscaled by the platform itself when setting the video output to 480p, and then will go through another downscale pass to 240p. Finer details will surely be lost, and small texts will be either difficult or downright impossible to read. Still, here is the proof of concept to show that it is possible. Check some examples below (all comparisons show 480p being displayed on a PVM-14L5 multiformat CRT monitor and 240p on a BVM-20F1U 15kHz CRT monitor):
Conclusions
After years unsuccessfully monitoring expensive and scarce specialized devices, it is finally possible to own a device that performs this very specific task of downscaling at an affordable price and that is wide available (at least while more people don’t take notice and hunt down all the stock of GBS 8200 on the market) .
With the GBS Control firmware, this board not only becomes a very capable upscaler, but also adds this downscaling function to your retro setup, offering very pleasing results with very fast performance (8 milliseconds to handle 480p signal, and up to 16 milliseconds to deinterlace 480i signal and downscale the image to 240p). The fact that the GBS 8200 only has VGA and component inputs (and also SCART with the GamesCare kit) and only outputs via the DE-15 (VGA) connector means that you will probably have to purchase a few additional specific cables to meet the needs of your setup, but the effort pays off. The range of possible applications is wide, as we have described on our test, and we invite everyone to carry out further experiments and share results.
For the future, there is hope for an update to the GBS Control custom firmware that improves the 480i signal deinterlacing of the downscale function, solving cases of blurred image due to field prioritization problems. And we’ll also keep an eye on the OSSC Pro to see what it will offer with its promised downscale feature. For now, we will continue having fun fiddling with the GBS Control features. Meanwhile, if you also enjoy the GBS Control, consider supporting the project’s author at https://www.buymeacoffee.com/ramapcsx2.
