Question about YUV

[panzeroceania]

This may be a stupid question, if so, I apologise in advance.

So the earlier video game systems were incapable of outputting RGB, if I understand it correctly. You could use a YUV to RGB transcoder, and could probably get a perfect conversion, but I was wondering if there were any displays that accept YUV as 3 separate channels like RGB monitors.

I'm thinking about systems like:

atari pong, atari 2600, Sega SG-1000, atari 7800, etc.

what is the situation with consoles like these? do they have RGB at all? like the NES, N64, PC Engine, Intellivision, etc, and it just has to be tapped from the chip, or is there simply no RGB at all.

thanks in advance for the education.

[Midori]

YUV is only output by a few consoles, far from all.

YUV is fairly compatible with most TVs component video inputs, although it should be noted that all CRT tubes work with RGB(unless they are black-and-white) so all signals that are input into a CRT display will be converted to RGB anyway.

Sega SG-1000 has RGB, Atari 7800 and 2600 can be modded for S-Video or composite. Pong I do not know about, although it might be similar to the 7800 and 2600.

Mostly you can't really group consoles like this but you have to do research for each console, since they all have different video chips which outputs different signals. There is no such thing as in "all consoles made in the 80s" have RGB :-)

[panzeroceania]

ah, so if all signals have to be converted to RGB eventually anyways, then you might as well convert the signal to RGB right away.

The only exception being pong, which is black and white. In this case are there any black and white TVs/Monitors that just accept a pure "Y" signal, or is there no such thing.

[Midori]

There are black and white TVs and monitors, not too uncommon. But every normal colour TV is capable of displaying it perfectly well anyway so there is no real point i getting a monochrome TV :-)

[panzeroceania]

I thought all those tvs accepted either RF ( a mix of YUV) or Composite (a mix of RGB) I didn't think any of them accepted a pure Y signal, or a seperated Y, U, and V signals.

[viletim]

I thought all those tvs accepted either RF ( a mix of YUV) or Composite (a mix of RGB) I didn't think any of them accepted a pure Y signal, or a seperated Y, U, and V signals.

Every TV will dispaly a pure liminance (Y) signal. You can connect it directly to a composite video, s-video, or component video input. Also by RF if you modulate it onto a carrier.

More info:
http://members.optusnet.com.au/worthair/sc_vid/

[panzeroceania]

ah yes how silly of me, component cables have a whole cable dedicated to Y.

I seem to remember hearing that color TVs always have to convert a signal to RGB to physically display it, is this true? if so it would seem best to convert a signal to RGB as soon as possible with hopefully better equipment than your TV would use to convert it.

If not, it would make sense with systems that do not output RGB at all to keep them in YUV so as to not convert the signal at all and keep it pure.

[Midori]

A colour CRT Tube always works with RGB in the end, so if a RGB input is available it is the best possible choice. And yes, external converters of decent quality can give quite the performance jump.

[TrekkiesUnite118]

A colour CRT Tube always works with RGB in the end, so if a RGB input is available it is the best possible choice. And yes, external converters of decent quality can give quite the performance jump.

I have a question then, do you not need an RGB to YUV converter like the CSY-2100 to use RGB on an American CRT if all CRTs work with RGB? Could you just get away with a Scart to component adapter then?

[Midori]

I have a question then, do you not need an RGB to YUV converter like the CSY-2100 to use RGB on an American CRT if all CRTs work with RGB? Could you just get away with a Scart to component adapter then?

There is no widely implemented RGB connector in the US so there are usually no RGB inputs on an American CRT TV. If you have a videogame or similar that only ouputs RGB and a TV with no RGB input then you need to convert the signal to one that the TV accepts.

If there is no RGB input on the TV it doesn't really matter that on the inside the signal will have been converted to RGB before feed to the tube :-) Since you can't access it directly. You have to use whatever other input there is on the TV, like component. Unless you hack the TV... But that is nothing for... most people(that includes me, so you won't have to assume that).

A TV has two major components, the tube and the chassis board.

The chassis board recieves the video signals, processes them, controlls the CRT tube and feeds the CRT tube with an RGB image to display.(it also supplies voltage and such).

The tube recieves an RGB signal from the chassis boards and displays it according to how the chassis board tells it to.

If the chassis board doesn't have an RGB input then RGB isn't an option. You can't feed the tube directly with signals from a console or such, the signal needs to be worked with before the tube can display a good image with it.

[panzeroceania]

I misspoke earlier, component is a mix of YUV, not RGB, and yes component cables have a pure Y signal and RF, Composite, and S-Video have a Y signal mixed in and most TVs accept that as an input, however, all TVs need the information to eventually be put to RGB to physically put it on the screen, so although all color TVs can display black and white games like pong just fine, they are converting it to an RGB value, either (R=0, G=0, G=0) or (R=255, G=255, =255) This really doesn't matter I suppose because black and white are very absolute colors/signals so it would be hard to misrepresent them, but I was just thinking of the theory that, ultimately all color TVs are converting whatever sinal you are giving them to RGB even if they have a bad source, so you should feed any TV RGB even if you have to use external equipment to achieve this, such as the Atari Systems that cannot output RGB.

What  was getting that is, what does a Black and White TV send to it's tube? a pure Y signal? if so then if you modified a pong system (which only uses black  white) to output a pure Y signal, and then modified the tv to accept that (most black and white TVs would only accept RF I'd imagine) would you be able to pass the direct signal from the pong to the TV with ZERO conversion, or is the signal still converted to some other kind of information to be displayed on the screen.

again, with black and white it doesn't really matter because they are such absolute colors but it is more about the ideals that it is always best to send a direct, unconverted signal rather than having a signal be converted.

that is of course unless I am assuming something wrong, maybe pong does not output a Y signal, or maybe a black and white tv does not accept a y signal, or maybe it converts it to something else to physically display it on the tube, there are simply to many unknowns.

Also, what is the case with systems like the NES, PC Engine, N64, etc.

especially the N64. How come they do not output RGB? surely on the internal chip it is sending RGB because that is how computers describe colors is it not?

I am assuming in the case of the later N64s that they do in fact have RGB internally but it is just imposible to get to that information for a mod without destroying part of the console, right? because I know you can do RGB mods on the nes and N64, I was just curious why it isn't readily available on on the chip in the system.

A colour CRT Tube always works with RGB in the end, so if a RGB input is available it is the best possible choice. And yes, external converters of decent quality can give quite the performance jump.

that's exactly what I thought, thank you!

and yes, I understand that most TVs, even if the tube requires/gets an rgb signal, most chassis in US TVs don't allow you to input anything but RF, composite, S-Video, or component, thankfully I have a15khz RGB monitor from Sony.

again, I suppose the only exception or fringe case would be a black and white TV, I'm assuming it would not convert anything to RGB but instead would just maintain a pure Y signal to the tube?

[bigsanta]

YUV is only output by a few consoles, far from all.

YUV is fairly compatible with most TVs component video inputs, although it should be noted that all CRT tubes work with RGB(unless they are black-and-white) so all signals that are input into a CRT display will be converted to RGB anyway.

Sega SG-1000 has RGB, Atari 7800 and 2600 can be modded for S-Video or composite. Pong I do not know about, although it might be similar to the 7800 and 2600.

The sega sg-1000 doesn't have rgb capabilities ! The TMS9918A ic it uses has composite ,as it's best output ,there's no rgb available from it.I modded the one i had and the data sheet notes a 330 ohm pulldown  resistor on the cvideo line ,which helps with sharpness of the video.A lower value resistor gives faster fall times ? and a sharper picture.
http://emu-docs.org/VDP%20TMS9918/Datasheets/TMS9918.pdf

http://en.wikipedia.org/wiki/Texas_Instruments_TMS9918#Specifications

[cgm]

Every TV will dispaly a pure liminance (Y) signal. You can connect it directly to a composite video, s-video, or component video input. Also by RF if you modulate it onto a carrier.

More info:
http://members.optusnet.com.au/worthair/sc_vid/

Some flat panel displays flip out if you feed them a pure Y signal since they usually expect a color burst signal. Then there are some consoles/home computers that don't quite output a RS-170A compliant signal from their composite output. For both cases passing though a time-base corrector or other video processor with solve the problem. They strip out the non-standard sync and generate compliant sync and color burst signals.