640×240 Optimized Mode

[ExoParadigmGamer]

Hello, fellow OSSC owners. After playing around with settings for hours, I’ve become curious about whether the next OSSC firmware could include a 640×240 optimized mode for N64. The 256×240 mode for S/NES has been a great inclusion for pixel accurate sampling of those consoles, and I believe a 640×240 mode could produce similar results for N64.

The N64 natively outputs most games (but not all) in 313×237 and then pads out the image to 320×240 with black pixels. It is currently possible to sample this framebuffer image using these settings from Junker HQ. While this is great for those who like their N64 video deblurred (in an effect similar to the Ultra HDMI’s deconvolution feature), it is not accurate to the source video.

As part of the N64’s anti-aliasing procedure, the console takes the 320×240 framebuffer image and interpolates it 2x horizontally to 640×240. On a CRT, this provides smooth looking scanlines that reduces aliasing, given how analog video does not have a fixed horizontal resolution. A 640×240 optimized mode on the OSSC would allow users to easily and accurately sample the N64’s native output while maintaining the correct aspect ratio. Essentially, the H Active would be set to 640 with appropriate settings while the V Active would remain at 240.

It’s currently possible to get an upscaled image pretty close to this in Generic 4:3 (1280×240) mode, but I’ve since learned that the OSSC adds additional interpolation in this mode and that it is still not accurate to the source image. I’ve tried changing the Generic 4:3 timings to H Active 640 and the like, but my displays and capture devices won’t recognize the signal. Even the Framemeister, which I use to normalize OSSC footage for recording on my Elgato, will not recognize it. It does, however, recognize the other optimized modes.

While it is technically possible to sample this way with the Line2x Mode Generic 4:3, I would prefer a version of this that would work in other Line multiplier modes.

If I could get more information about the possibility of such a feature in future firmware, or perhaps a workaround within the current .80 firmware, that would be great. Many thanks.

P.S. A similar 512×240 Optimized Mode would also be great for hi resolution SNES games and other 512 anamorphic games like Pac Man World or Spyro the Dragon. There could be an aspect ratio toggle for pixel accurate, 8:7 and 4:3 aspect ratios similar to the 8:7/4:3 on the 256×240 mode.

[CompositeKing_GQS]

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[YoshiSprite]

Nobody cares about perfect pixels, unless they’re used to make Yoshi sprites.

[Harrumph]

I don’t really see the point of such a mode for N64. The blur feature was created exactly to reduce sharpness on the horizontal axis (as you said a sort of anti-aliasing feature). This is best captured with generic 4:3 (which, btw, does not do any interpolation, it just samples at a high enough sample rate to adequately capture the continuous nature of an analog scanline).

If you were to do optimized sampling for the 640 width, the result would look extremely weird as you’d have repeated “sharp” pixels followed by repeated “blurred” pixels. I can only imagine this will result in some horrible looking vertical banding.

[nmalinoski]

The vast majority of DDR games, if not all of them, on PS1 and PS2 use 640×240 during gameplay; could be another use case for a 640×240 optimized mode.

[ExoParadigmGamer]

In response to Harrumph, you bring up some valid points. However, as a content creator, I prefer sampling analog game video as accurately as possible, regardless of how good it necessarily looks. I want footage that is as accurate as possible for my reviews, and while I personally prefer the deblurred N64 settings, it isn’t accurate to what the system is outputting. Personally, I think pixel accurate N64 looks nice enough, if the more accurate Angrylion Project64 plugin is anything to go off of. I’d upload some photos, but I can’t seem to get the forum to accept any of my links.

Plus, having a dedicated optimized mode will make it easier for users to sample their N64, just like the 256×240 mode streamlines that process for NES and SNES. I also find that displays are more tolerant of the OSSC when non-standard horizontal resolutions (like 512) are sampled within a standardized H Active (like 640). This means that the 640 mode could have additional applications for sampling games that run in anamorphic aspect ratios while keeping an aspect ratio closer to 4:3. As Nmalinoski also notes, there are also games that natively run at 640×240 which could use this option.

Regarding the issue of whether Generic 4:3 interpolates, I heard that from a friend who also owns an OSSC and is generally pretty knowledgeable, though he may be mistaken on that point. While I can get pretty close to the image I’m looking for in 1280×240, the obsessive part of me just wants to get that extra bit more accurate as well as the ease of use.

[BuckoA51]

Accurate to what though? It has to be said, no display would have ever looked like that.

[ExoParadigmGamer]

My goal is accuracy to the 640×240 frame that the system is outputting. Since YouTube and MP4 video is all digital, I’m limited accuracy-wise in terms of making things look exactly like they do on a CRT. That’s why I aim for what the original digital image looked like, before the DAC conversion. Since the N64 digitally outputs a 640 wide frame, that’s the frame size I would like the OSSC to sample from the console’s RGB output. I believe an optimized mode for higher line multiplier modes would be useful for this purpose.

I’d also like to state for the record that N64 games look pretty nice this way, if the accuracy driven Angrylion plugin is to be believed. The game designers intended for games to be interpolated this way and drew 2D assets accordingly. That’s why many 2D assets lack built-in anti-alias shaded pixels on the edges, because the horizontal smoothing feature would have added them instead. Hopefully I can get the forum to accept the links, this time. Take a look at these screenshots from the plugin and judge for yourselves.

I can also confirm that this is pretty close to what these games look like on my PVM, so it more or less looks like that on my display.

[ExoParadigmGamer]

Here are some direct links to those screenshots in the full 1280×960.

Banjo Kazooie

Glover

[Harrumph]

Yeah that looks quite good. I had a brainfart anyway and didn’t think about that pixels are only doubled on the horizontal.

[Author]

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