Pixel-Accurate N64 Software Video Plugin

[ReyVGM]

Originally Posted by HatCat

What's the difference between LCD and CRT? CRT is like them rounded-surface TV screen thingies or something is it? And I guess LCD is the more modern, digital flat-looking screens. See I'm not lying when I say I don't know shit :P

You are really serious?

Basically, CRT means Cathode Ray Tube. You have literally a cathode tube shooting rays of light to the screen, which is coated with phosphor. Those phosphors ignite when the ray hits them and that's how you see an image.

Have you ever seen in old movies or the news, that whenever they showed a TV or an old computer monitor, you would like like a black bar scrolling down?
You were looking at the refresh rate, or better yet, the gaps of where the Ray hasn't hit yet.

You could say a CRT is sort of like a projector in which the ray can shoot and create whatever size it wants and you would just see an image, like in the movies, and not a combination of pixels forming an image. And since everything looked blurry, it was difficult to notice when something was scaled to fit the screen because all the "pixels" just bled into each other, creating that undefined smudged look.

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LCD means liquid crystal display. You remember those old calculator screens? Or the old Game Boy screen? Those are all LCD, colorless, but still LCD.
The screen is composed of several layers with a specific set of pixels. Unlike CRT or Plasma, LCD does not emit light, so you have to put some kind of light source in it if you want to see the image the pixels form. LCD traditionally uses fluorescent light tubes (same one you see in offices).

LED is the same as LCD, except instead of using a fluorescent light tube, it used LED's (light emitting diodes). The correct term should be LCD LED TV, but that's a mouthful and people just called them LED and everyone thinks it's some kind of new technology not knowing it's still an LCD screen with a different light source.

[run of the mill twat]

what he said

[GPDP]

Since we're on the talk about resolution and displays, I have a quick question. People here are saying while the resolution of (most) games on the internal N64 framebuffer is 320x237, the VI resolution is 640x480, and thus on the emulator, the most accurate way to display the image is to display it at 640x480 or whereabouts. However, how can this be the case if, on real hardware, the output is blatantly non-interlaced 240p? If it was 640x480, the output would be interlaced with obvious flickering (at least on CRTs), but for the vast majority of N64 games (and most everything older, for that matter), this is not the case.

There was a comment on the last page that mentioned Mario 64 being scaled to 640x237 by the VI interface, though. I am assuming that is the interpolation at work? I have noticed that on a 640x480 screenshot with the VI filters on, there is but one pixel of horizontal blur along edges, which is why if you try to scale the image down to 320x240 through nearest neighbor, you end up losing some detail.

[HatCat]

It is 640x240 but the video DAC active lines is only 237.
Actually the picture stored in RDRAM memory, is 320 pixels wide, not 640x237, but accurate VI emulation is required to scan in pixels using a special algorithm (and if anyone just arrogantly assume angrylion is full of shit about this then you also think that Silicon Graphics' repository and hardware info is full of shit and you should feel convinced enough to carry your rebellion into a new emulator). The TV itself must scale the 240 pixels to 480 or 576 in PAL cases; this results in the 640x480 images we've been posting here, either NN with the s-video/rgb-upscaler or bilinear with that composite capture.

The unscaled image sent to the VI is 640x240. The N64 multiplies 640 * VI_X_SCALE reciprocal and 240 * VI_Y_SCALE reciprocal to scale to the 640x480 NTSC TV or 640x576 PAL TV.

I have noticed that on a 640x480 screenshot with the VI filters on, there is but one pixel of horizontal blur along edges, which is why if you try to scale the image down to 320x240 through nearest neighbor, you end up losing some detail.

It should be fixed in the OpenGL build. I tried both GL_LINEAR and GL_NEAREST...both NN and bi-linear give the same exact, crisp, un-blurred image when scaling a 640x480 size to a 320x240 screen. So it should look like the screenshots.

[GPDP]

That's the thing, though. A standard definition CRT TV does NOT scale up to 480 lines, because unlike LCD displays, it does not scale at all. The only games that ever display 480 lines are, well, those that actually output a resolution with 480 lines, and those tend to be interlaced. This is easily seen with a game like Rogue Squadron, which has options for resolution. Normal resolution on my CRT outputs a "scanlined" image with no interlacing (this is commonly known as 240p), whereas the High resolution setting ups the vertical resolution to 480 lines, with visible interlacing flicker instead. The vast majority of N64 games run in the non-interlaced mode, which is why it does not make sense to me that the "accurate" output should be 640x480, as that is most definitely what does not happen on real hardware on a CRT (what the N64 was primarily made to be played on), outside of a handful of games.

[HatCat]

All I'm saying in this case is that the N64 outputs video at 640x480, no matter what game is playing.

If you do no scaling whatsoever, Mario will come out to 640x237, not 640x480, not 320x240.
And at that fateful point, whatever the hell TV's do with that resolution doesn't interest me. I like DP emulation, not TV hardware.

[e2118289]

Why is your plugin so slow, HatCat?

[GPDP]

Then 640x237 is what is actually being output, as you said.

Keep in mind, the NTSC standard technically is 640x480 interlaced. However, old consoles did a neat little trick where as opposed to drawing even fields on one frame and odd fields the next (i.e. interlacing), they instead make it so the TV only draws on either the even or odd fields, halving the resolution but resulting in a non-interlaced image, which is far less flickery. This non-interlaced mode, however, is not actually officially outlined by NTSC standards, so in most official documentation, only interlaced 640x480 is talked about. Perhaps this is what is being referred to when you say the N64 outputs a regular NTSC signal.

Just saying, as someone who has some knowledge of resolution and display standards, and has a real N64, there is no way in hell Mario 64 or the vast majority of N64 games output 640x480 in the real world. I do buy 640x237, though, as again, some horizontal interpolation is present.



This is a depiction of what Mario 64 looks like on a CRT (albeit a very rough one, given not all TVs has such prominent "scanlines", and of course, an LCD cannot accurately portray the phenomenon). If it was 640x480, instead of static black lines, you'd instead see alternating even and odd fields being drawn, as such:

[RPGMaster]

Originally Posted by e2118289

Why is your plugin so slow, HatCat?

Lol... Why are you interested in Shunyuan's slower and more resource intensive plugin?

[timde9]

this plugin is not showing up in my plugins list in project 64 the latest 2.1 public release. How do i get it to show so I can use it. Thanks.