When NTSC filter is mandatory?

[Hyllian]

I was running SMW on a CRT using Snes9x through composite cables just to see how the visuals are affected by this input. Something came to my attention when I entered this water screen:

The water is dithered. But on a real crt through composite it shows some rainbow effect (a la Sonic Waterfalls).

So I tried to reproduce that visual using RA and ntsc-adaptive shader. For my surprise, the vertical rainbows are only possible by setting config to Phase 2 (the genesis config) + Resolution Scaling 1.20 or 1.25, Color Artifacting above 0.50 and Chroma Scale above 2.00. Using Phase 3 is impossible to get vertical rainbows, which raises a question if indeed snes through composite is accurately represented using Phase 3 config?

[Jamirus]

What’s the actual hardware you used for this (ie. the non-SNES composite device)?

[Hyllian]

Wii and composite cable. Not a real snes, though Snes9xGx is configured to output 240p. I doubt there’s a real difference here from a real snes.

[Jamirus]

I’d be interested in seeing the Sonic waterfalls if you’re using a NTSC Wii. On my PAL Wii, it’s definitely vastly cleaner over a real Genesis, but the PAL console outputs always PAL 60, which I assume also makes quite a difference. The Wii also always scales the output digitally into the 640px range, it works a bit differently compared to real consoles in this regard.

[DariusG]

Probably Wii outputs 320p (or 640?) horizontally and stretches the snes 256 that’s why it needed the megadrive setting. And that rainbow wouldn’t be there on a real snes most probably as it outputs 256. Just a guess and I could be wrong.

[Hyllian]

You’re right! After reading this Thread I learned that the Wii doubles the horizontal resolution of 256x224 snes games before sending to a CRT. So, these rainbows were the result of sending a 512x224 or 640x224 resolution to my screen. It’s a collateral effect of not using a real hardware.

[DariusG]

Yeah too many fine details that overlap with chroma causing rainbow effects.

[Jamirus]

Vague_Rant, who also made the Wii optimal video settings thread many years back, had a great article regarding Wii video on github which I can’t find anymore, but I saved it as pdf. This isn’t really directly related to composite though, but about the ratios, scaling and filtering. Downloadable here:

https://www.mediafire.com/file/opiglyi6gz1v0ee/Wii_Video_%C2%B7_GitHub.pdf/file

[Cyber]

Another thing is that systems that use 1 and 3 phase tend to produce diagonal rainbows, unlike the vertical rainbows produced by the Genesis in 2 phase mode, which is something that both Sonkun and myself had observed in our own research and implemented in our presets.

I remember posting some screenshots a while ago, maybe 1 or 2 years ago.Time flies so fast in these forums.

I found the post I was talking about.

CyberLab Death To Pixels Shader Preset Packs

For those who can’t stand playing SNES games without an NTSC Shader (or one that uses GTU), I present to you… CyberLab_SNES_Composite_Slot_Mask_IV_OLED_NTSC.slangp As you can clearly tell from the filename, it doesn’t require any additional video filters and it also doesn’t require BSNES Blur emulation to be turned on. So without further ado… Right click on the image, click Open in New Tab then press F11 for Fullscreen for 4K users. Zoom in until it looks right for 1440p or 1080p users. [K…

Here’s Genesis for comparison:

CyberLab Death To Pixels Shader Preset Packs

Right click on the image, click Open in New Tab then press F11 for Fullscreen for 4K users. Zoom in until it looks right for 1440p or 1080p users. Some of these NTSC effects can’t be captured properly using regular screenshots so what you see here is not necessarily what you will encounter while playing. CyberLab_Genesis_Composite_Slot_Mask_IV_OLED_NTSC.slangp [SONIC2-221230-232620] [SONIC2-221230-232636] [Streets of Rage 2 (Magical hack 2) (U) (X)-221231-024751] CyberLab_Genesis_S-Vide…

And here’s and example of what takes place on NES.

CyberLab Death To Pixels Shader Preset Packs

Just a little preview of some stuff I’ve been cooking up in the CyberLab. Right click on the image, click Open in New Tab then press F11 for Fullscreen for 4K users. Zoom in until it looks right for 1440p or 1080p users. CyberLab_Turbo_Duo_S-Video_Slot_Mask_IV_OLED_for_CyberLab_Blargg_Video_Filter_III.slangp + Blargg_NTSC_Turbo_Duo_SNES_S-Video_CyberLab_Special_Edition_II.filt [Shadow of the Beast (USA)-221220-032738] [Shadow of the Beast (USA)-221220-032817] [Aero Blasters (USA)-221221-…

[DariusG]

Some info about systems that can do artifact colors

Amiga: can do NTSC artifacts. The machine already had plenty of colors therefore the technique was not exploited. Plus, most of the users had RGB monitors. A possible exception is virtual karting 2.

Atari 8 bit: possible. 7.16mhz pixel clock on high-res (2x NTSC, 2 pixels share 1 color)

C64: the dot clock is not a multiple of the color clock. It is around 8.18Mhz for NTSC. This means that NTSC artifacts are visible using hires gfx but they will vary across the scanline and time, not usable. Other artifacts are were commonly used instead. Flickering and PAL delay line mixing.

ZX spectrum: pixel clock is 3.5 mhz, not a multiple of the color clock. Only the ZX spectrum 128 had same clock for color and pixels.

Zx81: it generates a color burst but the dot clock is related to the 3.25 MHz CPU clock.

Amstrad Cpc: the dot clock is 1mhz multiple therefore artifacts are not usable

Atari 2600: Each pixel is one ‘clock’ of the TIA’s processing time, and there are exactly 228 color clocks of TIA time on each scanline. But a scanline consists of not only the time it takes to scan the electron beam across the picture tube, but also the time it takes for the beam to return to the start of the next line (the horizontal blank, or retrace). Of the 228 color clocks, 160 are used to draw the pixels on the screen (giving us our maximum horizontal resolution of 160 pixels per line). No artifacts.

CGA: Possible. 14.31818MHz pixel clock max (4x NTSC)

Apple II, possible. the pixel clock is exactly twice the color clock. It has an option to turn off the color clock to generate reasonably crisp black-and-white text, then turn it on for the ability to generate artifact colors.

I general it’s possible if pixel clock is a multiple of the color clock (2x pixel clock, 2 pixels share 1 color etc). If pixel clock is 1x is not enough, each pixel has it’s own color. When pixel clock is not an exact multiple, it creates that rainbow artifacts

That’s a pretty big mistake on the ZX Spectrum design too, not using a 2x NTSC clock for pixels and create extra colors while it has a big problem with color attribute clash. A 14.316 master clock (the cheap crystal everyone was using) divide by 2 for dot clock and divide by 4 for CPU was the way to go.

[anikom15]

This is kind of tangential, but I think this info could be helpful to document. I recently went through some pain to determine what level of display beyond RF video was supported by various consoles and to what degree this support was official. Some of it was from memory. For example, I distinctly remember seeing ads for official S-Video cables for the N64. But most of it required digging for sources amid a sea of popular mods to get RGB output from various consoles. I won’t be discussing every console, just the popular ones.

Before the NES, hardly anything supported composite (RCA) output. Everything connected to a television via RF. This required a modulator to convert the baseband video signal from the console to a radio signal. There were two termination methods. One was a 300 ohm twin-lead and the other was 75 ohm coaxial (the same used for modern television antennas). Twin-lead is the worst option, being sensitive to interference. None of these mechanisms are consistent. The resulting picture quality doesn’t just vary among consoles, but also regions, as different regions required different modulation techniques and usable channels.

Composite (RCA, A/V) video was adapted fairly quickly in Japan but took longer in the West. Ironically the NES included direct RCA ports for A/V, whereas the Famicom was RF only. Third-party models and the later Famicom revision in 1993 provided A/V output.

Consoles moved to using ‘multi-out’ ports in proprietary configurations. This allowed different outputs using one jack. For example, the Sega Master System included an RF unit in most configurations, but an optional A/V cable could be purchased for composite video. Some consoles, like the PC Engine and Mega Drive (Genesis) provided pins to access RGB signals. However, the RGB outputs on these devices are very poor and do not seem to be meant for consumer use (perhaps rather for debugging and development). Using the RGB pins on the PC Engine results in incorrect colors, while the pins on the Genesis will show jail bars. Cleaning up this output requires mods. However, there is one instance where Sega did provide an official RGB solution for the Genesis, and that was specifically for French Mega Drives where SCART was ubiquitous.

Sega Master System manual showing included and optional accessories

Official Video Monitor Cable for Mega Drive, included with Japanese Mega Drives, but an additional purchase for other markets (a stereo version was released for the Mega Drive 2)

Rare SCART cable for French Mega Drives (does not work on other Mega Drives without modification)

The final fourth generation, the Super Famicom (Super Nintendo), is the first to officially support S-Video. It also supports RGB properly. Here are the official cables that were sold:

P/N	Description
SNSP-003	RF Switch
SHVC-007	Monaural A/V Cable
SHVC-008	Stereo A/V Cable
SHVC-009	S-Video (S-VHS) Cable
SHVC-010	RGB Cable (JP-21)
SNSP-015	Euro Connector Plug (Stereo A/V to SCART)

It’s important to note that the RGB cable is not a SCART cable and will not work with SCART TVs. It is actually a JP-21 cable. The pins are different. The RGB cable is a rare cable that was only released in Japan. The ‘Euro Connector Plug’ is simply an RCA to SCART adapter and does not provide any better image than standard composite. For RGB output on a US or EU SNES, a third-party cable would have to be used. These cables were not really available or used when the SNES was popular (SCART was not even used in the US at all).

The Saturn and PlayStation officially supported RGB with JP-21 cables, again only available in Japan. The Nintendo 64 oddly did not have any support for RGB, only RF, composite, and S-Video. That said, even in Japan the JP-21 connectors were never very popular, and by the time the N64 came around it was essentially a failed technology.

Sony did release a SCART cable for the PlayStation (P/N SCPH-1052).

The Dreamcast was an odd-duck. While it did support S-Video, it also supported VGA.

By this time, component video was also becoming more common. In the US, RCA connectors were used, which created a Hydra-looking thing that was a pain to plug in. Japan used a new connector called D-Terminal. The PlayStation 2 was the first console to officially support component. With the Xbox 360, consoles moved to HDMI, and that has remained the standard since (the Wii was limited to component video, however).

Below is a table showing the various output methods on popular consoles. Any corrections or additions to this table are welcome.

Console	RF	Composite	S-Video	RGB JP-21	RGB SCART	VGA	Component
Famicom/FDS	Yes	No	No	No	No	No	No
New Famicom (Not FDS compatible)	Yes	Yes	No	No	No	No	No
NES	Yes	Yes	No	No	No	No	No
Master System	Yes	Yes	No	3rd	3rd	No	No
Master System II	Yes	No	No	Mod	Mod	No	No
PC Engine (PI-TG001)	Yes	Add-on	No	Mod	Mod	No	No
PC Engine	Yes	Yes	No	Mod	Mod	No	No
Mega Drive (J) / Genesis	Yes	Yes	No	3rd	3rd	No	No
Mega Drive (PAL)	Yes	Yes	No	3rd	Yes (France)	No	No
Super Famicom	Yes	Yes	Yes	Yes	3rd	No	No
SNES	Yes	Yes	Yes	3rd	3rd	No	No
Super Famicom Jr. / SNES Mini	Yes	Yes	Mod	Mod	Mod	No	No
Saturn	Yes	Yes	Yes	Yes	3rd	No	No
PlayStation	Yes	Yes	Yes	Yes	Yes	No	No
Nintendo 64	Yes	Yes	Yes	Mod	Mod	No	No
Dreamcast	Yes	Yes	Yes	No	3rd	Yes	No
PlayStation 2	Yes	Yes	Yes	Yes	Yes	No	Yes
GameCube (NTSC)	Yes	Yes	Yes	No	No	No	Yes
GameCube (PAL)	Yes	Yes	No	No	Yes	No	Yes

[Jamirus]

With mods, I would think you can add S-Video and RGB to to anything mainstream these days.

The GameCube has an official RGB cable available (Dol-013), probably to compensate for loss of S-Video on PAL Cubes.

PS2 had the VGA adapter from the Linux Kit, although I’m not sure if that really counts as “VGA compatible” because of the sync on green signal.

[Ranmori]

@anikom15

|PC Engine|

Early PC Engine (PI-TG001) is RF only.
Later models including PC Engine CoreGrafx (PI-TG3) support composite.

Even PI-TG001 can output composite via the expansion bus when combined with a CD-ROM2 unit.

Also, being a Japanese site, it would be quite a challenge to browse while translating, but I believe this site is valuable in terms of information in terms of output.

https://dempa.jp/rgb/heaven/index.html

[anikom15]

Thanks for that link. I can read Japanese. The Wonder Mega supports S-Video, which is interesting.

[Ranmori]

Currently, Retroarch has a wide variety of NTSC shaders and presets, including RF/Composite/S-Video, which can be combined in various ways to achieve the image quality I want.

However, there is one problem.
That is Component. In Japan, it is called D-Video, which was used in PS1/PS2/PSP/Wii. early GC models also had it, but I doubt if the internal signal is D-Video or not.

Now, how does Component finish the NTSC shader parameters, I would love to see Component added to the NTSC presets.

Or is Component something that is not in demand?
It seems to look different from RGB.

[Ranmori]

I figured Component or D-Video because the three colors are physically independent.

I thought that simply setting “NTSC Blend Mode” to 0 in the NTSC shader would make it more like Component or D-Video.

[Syh]

Component definitely looks different than RGB, as it’s a different color space. (Besides color it’s largely identical tho)

[Jamirus]

Does it have a relation to NTSC though. Quality wise the differences between it and standard RGB are usually considered to be marginal at best. I’ve run component through a HDMI-VGA chain, that didn’t seem to degrade the signal very notably.

[Syh]

Honestly think it’s completely unrelated to NTSC but 🤷.

And yea, agree, quality wise, RGB = Component (if that’s what you’re saying, idk it’s been a long day don’t @ me )

[Ranmori]

I see now that I am on the wrong topic.