NES caracteristic Dot crawl while scrolling, shimmering, shifting pixels.

Well that's one of the goals with the universal ppu that I linked. The developers is going to make it with selectable color pallets to include the ntsc nes pallet as well as the arcade rgb and VS color pallets

More info here: http://forums.arcade-museum.com/showthread.php?t=251095

 

Sure would be awesome if this came to fruition!

 

I have made some new observations regarding the shimmering effect.

I modded my TG16 for S-video and it completely removes the shimmering. Game like SideArms that were Shimmer hell are completely cleaned in s-video.

Then i used my TV monitor output, which is a composite output at the back of my TV, and connected it to a second TV while the first one received the s-video signal.
The shimmering is back on the second TV!

This means that the shimmering is not caused by how the consoles mix the signals together. To clear the possibility of the shimmering in this case being created by the TV mixing circuit, I tried the same with a Snes and it does not shimmer on the second TV.

So it would appear the shimmering is caused either by the resolution used in those consoles not reacting well to composite, or by how the video signal are being outputted. Say, if chroma or Luma are out of "standard" frequency range, would it be what causes the shimmering when the TV decoder tries to separate them? But then this is very close to the definition of regular dot crawl which does not look or behaves all that much like the shimmering...

 

Dot crawl and shimmering are the same thing... The dot crawl on the NES, PCE and SNES (I think) are dithered which gives it the appearance of shimmering.

Each console's crawl has unique qualities. Yes it's somewhat based on the resolution/pixel clock (which for the NES, PCE and SNES are the same for the most part), but it also has to do with each line's timing and whether it periodically alters the timing, the subcarrier/pixel relationship, the pixel/pixel relationship, and the exact method of modulating the color components/whether there's distortion there, and more I can't think of.

S-video will never have any artifacts from intermodulation distortion because luma and chroma transmitted separately. Your monitor output will simply sum the components together to get composite. All old consoles inadequately filter luma and chroma to their respective bandwidths before modulation, but SNES may do it better than the rest if the encoder has a built in filter. That's why you get artifacts once they're summed to composite. Modern consoles have the best possible composite/S-video because they can use ideal phase shifters, ideal modulators, ideal delay lines and ideal high order digital filters.

 

Thanks for the explanations, Im not sure I understand everything with my limited technical knowledge but I think i can make sense of that.
I guess my definition of dot crawl was too specific. I read the Wikipedia about dot crawl again and they describe different forms of it, even citing old game consoles and computers.

I guess this probably refers to the "shimmering"

I found the shimmering weird as no amount of filtering would do anything to it, as opposed to what i refereed as ''regular dot crawl''.
They say on wiki, just like you did in your earlier post, that dot crawl was sometime used intentionally for some screen effect.
I guess its possible the NES shimmering was intentional but somehow i dont see how anyone would like it! I decided i would RGB mod a famicom and one of my main motivation was to get rid of it.

Talking of which, if you ( anyone ) own a PCE or TG16, S-VIDEO MOD IT! ITS AWESOME!!!

 

I would if it weren't already RGB modded and if I didn't have a RGB monitor. S-Video is definitely nicer than Composite. I imagine the Genesis with a good S-Video mod looks far better than it's pretty terrible Composite output. I wouldn't know for sure but I do know RGB looks way better.

 

I'd love to see PCE side by side with things like maybe SNES jr, Neo Geo, and CPS2, on enterprise grade monitors. Curious what game systems rank among the industry's purest clarity 15khz RGB.

 

How does one rank RGB clarity between apples and oranges?

 

So far the system with the best RGB signal I've seen is the MVS. SNES Jr. and Genesis (model 1) are similar to the MVS, though not quite as good. All other systems I've tried are below that, the SFC being the worst I've tried.

I can't imagine, and have never seen a better low-res image than my MVS over RGB.

 

Have a look at my RGB pages over here:

http://www.chrismcovell.com/gotRGB/screenshots.html

The top of that page briefly describes what you are experiencing. The NES basically rotates its artifacts through 3 different phases, which is quite a good method of averaging over time. Some systems (SMS, MD, Neo-Geo) don't do any averaging, thus you get an awful static pattern of artifacts on-screen.)

The Turbografx has a very good 2-phase artifact reduction process which can be switched ON or OFF by the game's programmer at will. Usually turned ON would be best for most games, but for games at higher resolutions (Sidearms, R-Type, Ninja Spirit, etc. use ~336 pixels-wide modes) this artifact reduction will have little effect... Shimmering comes back, especially for autoscrolling games. That's just an effect of the fact that the pixel clock for 3xx-wide screens is near a multiple of the NTSC colourburst frequency and so crosstalk is inevitable.

There is no "scaling" happening at all on these analogue game systems, so that word should not be introduced to muddle the discussion.

 

What's the criteria you're judging?

There's nothing special about the MVS' video output, it's practically identical to thousands of other arcade boards which output non-standard video. The reason it looks better probably is because its RGB components aren't passed through an ancient RGB encoder's amplifiers like they are with Genesis and SNES.

People by nature are biased by video content (the number of colors and the overall brightness) and resolution, or lack thereof. A lower resolution will have more pixel definition for a monitor's given bandwidth. Basically the only objective things you can evaluate is the DAC's slew rate, all of which should correspond to frequencies way above a monitor's bandwidth, and whether the signal picks up noise/is degraded by amplifier bandwidth or other unintentional filtering. No other design criteria can be held against the system.

I'm fairly certain Cave CV1000 hardware will best any of the systems listed because it drives the DACs with modern high source/sink current buffers, and uses SMT.

 

It's just my own subjective assessment, of course. I have no way of testing the signal itself. However, I think if you were here next to me, looking at my PVM, you would agree. I can say this about the MVS image: as nearly as I can tell, there's no noticeable noise, no artifacts (other than the "glow" common to all CRTs), and each pixel is clearly distinct from those around it. I don't have the technical vocabulary to describe it fully, but I have eyes, and I've never seen a better image at this resolution (~240p).

I should also note that the difference between the MVS and the SNES Jr. and Genesis is very slight. All 3 systems look very good. It's the difference between those consoles and others like the Saturn, N64, and SFC that's much more noticeable. Maybe I should make a thread with pictures, comparing the different systems.

I also have an ST-V, and while it looks very nice (better than the Saturn), I think it is not quite as good as the MVS in the "distinctness of pixels" category I spoke of earlier.

You could be right about that. I'd love to see what it looks like, but sadly I don't own one.

 

I finally have a RGB modded AV Famicom, its great! No more Shimmering

 

Rgb mods are the way to go to fix any of the above issues. the nes rgb ppu color diff is not worth worring about and well worth the trade off.
ive modded many nes and 3dos. i run these in rgb to my xrgb mini- nes,snes,n64,sms,genesis/cd/32x,saturn,dreamcast,t16,duo,super grafx,jag,neo-geo,cdi,3do,psx. all look so much better.

 

Cool. Care to share some pictures/video?

 

I used the F-labo kit from Japan. I took some pictures while i was assembling the circuit I also did a close to complete translation of the instructions.
I will probably make a thread about all this stuff and the finished product soon.

When i was doing the mod i ran into an Issue, the first PPU I received was defective. This kind of broke My momentum and i forgot to document the end of the process as i was focused on troubleshooting.