why does the gamecube have color dithering?

[MrWibble]

No, just stores the frontbuffer in YUV (saves main memory and bandwith) - because YUV is the output you send to TV anyhow.

Unless you're in Europe where RGB is probably more common.

Though the fact that we do actually have some TVs with progressive-scan, component, and for that matter, s-video, has competely escaped Nintendo so far. I hope, even if it doesn't do HD, that the Revolution has sane output options or this time I'll be boycotting the European version and considering an import instead.

 

[darkblu]

Unless you're in Europe where RGB is probably more common.

Though the fact that we do actually have some TVs with progressive-scan, component, and for that matter, s-video, has competely escaped Nintendo so far.

correct me if i'm wrong but wouldn't the XFB's YUV suite nicely anything up to component? and not that RGB could not be nicely obtained from that, of course, but i still suspect the GC can keep an actual RGB front buffer (that's exactly why i was curious about the other pixel formats the XFB supports).

I hope, even if it doesn't do HD, that the Revolution has sane output options or this time I'll be boycotting the European version and considering an import instead.

erm, this 'discrimination' re the digital output not available to PAL territories was 'resolved' by ninty long time ago (by removing said output from all territories models). since i got my GC rather late in its lifecycle, i do find it weird that of all my consoles the one i play the most produces the lowest signal quality (my dreamcasts are hooked to my desktop monitor and my pstwo uses component cables (two-for-a-kidney, sony-made)).

 

[MrWibble]

correct me if i'm wrong but wouldn't the XFB's YUV suite nicely anything up to component? and not that RGB could not be nicely obtained from that, of course, but i still suspect the GC can keep an actual RGB front buffer (that's exactly why i was curious about the other pixel formats the XFB supports).

That seems to be what happens with the PAL cube - it's RGB or composite video only. No component, no s-video. The progressive mode which I understand is available elsewhere in the world is replaced with a 60Hz (woo) option for us lot.

I was gutted to discover that my Cube actually had inferior video quality to my N64 (which was using s-video) because I can't devote my only RGB scart to it, and then to discover that if I'd bought an import instead I'd have component output and progressive scan.

 

[vazel]

the new model gamecubes in america don't have component output either. http://www.nintendo.com/consumer/systems/nintendogamecube/component_faq.jsp

 

[vazel]

i take it since this a problem with the framebuffer not even getting component will help like some have claimed?

 

[darkblu]

vazel, if you refer to the banding/dithering observed by some, it could be
A) due to the back buffer switching to 16bit format when fsaa is in use, which i seem to have memories of reading somewhere, but i have not been able to rehash on that, nor has it been confirmed by insiders, so it's as good as a speculation ATM.
B) the use of some low-fidelity texture formats under some disadvantageous conditions. unfortuately i don't have the titles you mention as exhibiting the issue, so i can't comment on the artifacts. can you submit some screenshots?
C) the use of some particular multi-pass shading techniques or ones that have inherent reqirements for higher precision than the one standartly provided by the pipeline.

of the above, only option (A) can be seen as some form of an 'inherent problem' for the particular platform, the others are commonly met on any piece of graphics hw ever made.

 

[vazel]

this dithering is mentioned on the gamespot review of windwaker. this review of prince of persia: warrior within mentions that the gamecube version has 'bad color dithering'.

also found this thread at planetgamecube. they mention another problem in that thread where fog in wind waker becomes pixelated in progressive scan. so if running games in component progressive scan does reduce this visual anomaly like some claim your just trading one problem for another...

"Running the game in p-scan mode, the fog manifests itself as a strange translucent pattern of squares. It's hard to explain; maybe I can get a screen cap."


YES, and a screen cap would not due this issue justice (if you could get it at all). The dithering effect in Wind Waker’s fog (and elsewhere) is also found in Eternal Darkness. Why does this exist, and why only in progressive scan mode? Simple: think back to Super Smash Bros Melee and its deflicker filter, which averages pixels to make things softer. Well just about every GameCube game leaves that filter on for interlaced mode and off for progressive mode. However, the fog in WW and ED is created in such a way as to rely on this averaging of pixels to make their fog look natural! I'm not sure why the fog was done this way--perhaps leaving it to the deflicker removes extra overhead. I for one was bugged the hell out by the pixilated fog the first time I played both ED and WW in progressive scan. Hopefully Nintendo will fix this problem in future games.

 

[Bohdy]

If you are talking about the vertical pinstripe effect in WW (and perhaps other games) then I don't thinks its actually dithering.

I did some testing to determine the source of this and I have found that in a scene where I can clearly see it on my TV, it is not present in a dump of either the front or backbuffer. It must be an artifact of something that happens in the TV-out DAC.

Otherwise, the banding seen in several games is because of an effect running into the limitations of the gamecube (as already described).

 

[Fox5]

No, just stores the frontbuffer in YUV (saves main memory and bandwith) - because YUV is the output you send to TV anyhow.

Aw, I ordered a VGA cable for GameCube assuming it output RGB and that the component cables then converted it to a YUV signal. (what the heck is that DAC in the base of the cable doing anyhow? I assumed it was both a digital to analog conversion, along with a RGB to YUV conversion...so in that case the VGA cable is digital to analog plus YUV to RGB?)

Is the YUV or RGB framebuffer a developer's choice or a necessity with GameCube?

 

[darkblu]

Aw, I ordered a VGA cable for GameCube assuming it output RGB and that the component cables then converted it to a YUV signal. (what the heck is that DAC in the base of the cable doing anyhow? I assumed it was both a digital to analog conversion, along with a RGB to YUV conversion...so in that case the VGA cable is digital to analog plus YUV to RGB?)

well, theoretically YUV<->RGB conversion, especially at the source should not lose fidelity. actually the problem is not so much in the source pixel format and possible conversions before transmition as it is at the receiver's end - as s-video combines U and V, and composite combines them all in a single carrier, naturally the decomposition at the receiver's end suffers from those, particularly with the latter. but you shouldn't worry about that order of yours. i'm facing a much tougher luck here - i have to negotiate with ninty tech support a possible replace of my post-2004 cube.

Is the YUV or RGB framebuffer a developer's choice or a necessity with GameCube?

all i know is that according to YAGCD the XFB (i.e. the front buffer) supports several pixel formats (one of them being an optimised YUV).

 

[fearsomepirate]

That seems to be what happens with the PAL cube - it's RGB or composite video only. No component, no s-video. The progressive mode which I understand is available elsewhere in the world is replaced with a 60Hz (woo) option for us lot.

I was gutted to discover that my Cube actually had inferior video quality to my N64 (which was using s-video) because I can't devote my only RGB scart to it, and then to discover that if I'd bought an import instead I'd have component output and progressive scan.

Ummm...unless the European Cubes are totally different, it uses analog output cables that the N64 used. I've been playing all my Cube games with an S-Video cable since the day I bought the thing. It does make things look quite a bit sharper than the composite cables. Madcatz used to make a Cube S-video cable for a while (I have one), but I guess it didn't sell so hot. Both Intec and MadCatz make universal cables that do the same thing, though:

http://www.amazon.co.uk/exec/obidos...8-6/ref=sr_8_xs_ap_i6_xgl/202-5822403-5710236
http://www.amazon.co.uk/exec/obidos...8-2/ref=sr_8_xs_ap_i2_xgl/202-5822403-5710236

 

[Fox5]

Ummm...unless the European Cubes are totally different, it uses analog output cables that the N64 used. I've been playing all my Cube games with an S-Video cable since the day I bought the thing. It does make things look quite a bit sharper than the composite cables. Madcatz used to make a Cube S-video cable for a while (I have one), but I guess it didn't sell so hot. Both Intec and MadCatz make universal cables that do the same thing, though:

http://www.amazon.co.uk/exec/obidos...8-6/ref=sr_8_xs_ap_i6_xgl/202-5822403-5710236
http://www.amazon.co.uk/exec/obidos...8-2/ref=sr_8_xs_ap_i2_xgl/202-5822403-5710236

I heard the pin layout was changed on the analog out on the gamecube, so n64 svideo cables don't work properly. I know that gamecube won't output RGB over the analog port, it requires a modded digital cable.

 

[vazel]

i have to negotiate with ninty tech support a possible replace of my post-2004 cube.

from what i've read on the nintendo forum the exchange is only valid for 6months after purchase. after that they charge you $35 for a core system(without any controllers or cables) to be shipped out to you. you get to keep the gamecube you already have. i'd personally pay the $35 to avoid the hassle of cross shipment.

 

[fearsomepirate]

I heard the pin layout was changed on the analog out on the gamecube, so n64 svideo cables don't work properly. I know that gamecube won't output RGB over the analog port, it requires a modded digital cable.

I've interchanged my Cube and N64 cables before, but just the composite cables. In fact, my Cube is currently hooked up to my mom's TV through my N64 cable. Are you sure about the no RGB? Nintendo makes (made?) a SCART cable for the Gamecube:

http://www.amazon.co.uk/exec/obidos...8-1/ref=sr_8_xs_ap_i1_xgl/202-5822403-5710236

Weird that it doesn't have audio plugs for a receiver, tho'. Hope your TV has audio outs!

 

[Fafalada]

due to the back buffer switching to 16bit format when fsaa is in use, which i seem to have memories of reading somewhere, but i have not been able to rehash on that, nor has it been confirmed by insiders, so it's as good as a speculation ATM.

FSAA pixel format is limited to 16bit. Problem is that even with that it takes double the space of the non-AA mode, so you can only fit half the buffer in VRam.
It'd be interesting to see statistics how many games actually used this mode - I somehow doubt there have been many.

all i know is that according to YAGCD the XFB (i.e. the front buffer) supports several pixel formats (one of them being an optimised YUV).

I thought so as well but right now I've been looking and I can't find any mention of other formats Granted I don't have the most recent files here, so who knows.

Anyway one other explanation of these issues could be that 6:6:6:6 format is more popularly used then we imagine. Maybe the emulation guys can shed some light on this.

 

[Fox5]

from what i've read on the nintendo forum the exchange is only valid for 6months after purchase. after that they charge you $35 for a core system(without any controllers or cables) to be shipped out to you. you get to keep the gamecube you already have. i'd personally pay the $35 to avoid the hassle of cross shipment.

$35 is pretty cheap for a gamecube, I think they still go for more than that used.

I've interchanged my Cube and N64 cables before, but just the composite cables. In fact, my Cube is currently hooked up to my mom's TV through my N64 cable. Are you sure about the no RGB? Nintendo makes (made?) a SCART cable for the Gamecube:

http://www.amazon.co.uk/exec/obidos/...822403-5710236

Weird that it doesn't have audio plugs for a receiver, tho'. Hope your TV has audio outs!

The n64 svideo cables work on cube, but supposendly only put out a composite signal.
Oh, and I assume SCART carries audio as well? That does appear to be an official nintendo cable, and assuming it actually is for gamecube and not n64 it could be that it only outputs an svideo signal rather than RGB.

 

[MrWibble]

The n64 svideo cables work on cube, but supposendly only put out a composite signal.
Oh, and I assume SCART carries audio as well? That does appear to be an official nintendo cable, and assuming it actually is for gamecube and not n64 it could be that it only outputs an svideo signal rather than RGB.

The N64 svideo cables don't work in Europe. The RGB (scart) cables don't work in the US. The different territories get slightly different hardware, as well as software. AFAIK it's a relatively simple hack to change it, but I couldn't be bothered performing surgery on my console for this.

Even if you've got the extra port on your cube, a component cable, and a progressive capable TV, if you're using European software you'll not be able to use any of it. Nintentdo dropped support for the European market and the only addition was RGB and a 60Hz option (for some titles).

Considering that all the hardware was there apart from some minor internal crap that everyone else seems to have no trouble with, I really think Nintendo screwed over a portion of the market here for the sake of a tiny saving. Thats why I'll be waiting to see what they do with Revolution before I buy one here.

 

[Ooh-videogames]

Metroid titles lack any sort of dithering, are 24bit textures in use on those titles.

 

[Fox5]

Metroid titles lack any sort of dithering, are 24bit textures in use on those titles.

What Metroid games are you playing? Transparencies in metroid prime 1 and 2 are full of dithering, especially when running interlaced or with lower quality cables.

 

[Ooh-videogames]

What Metroid games are you playing? Transparencies in metroid prime 1 and 2 are full of dithering, especially when running interlaced or with lower quality cables.

Well, I play the games on my PC monitor thorugh component cables. So I guess thats why I never noticed them. Also I was more focused on the architecture and Samus/enemies, didn't really take into account transperencies.