Please help me understand!!! (RGB, Component, YUV, YPbPr - arrrrgh!!!)

Matt_C

Distinguished Member
Right, I am getting VERY confused about the difference between RGB Scart, RGB in general, componant RGB, component YUV, and all that stuff....

Please someone tell me what the difference is!

This is where it stems from;

I have a Sony DVD player, that (other than rubbish composite video (yellow plug) output) only has an s-video out and a scart out, which is RGB. Great I thought, my TV has an (RGB) scart input, and 2 non-RBG scart inputs. That is untill I wanted to connect a freeview box, which also has an RGB scart output...

My TV also has a component input, consisting of 3 rca/phono inputs, one is green, one os red and one is blue. Next to them they have Y PB Pr, looks like this;

rgbsockets.jpg


Anyway, I bought a lead that has scart on one end, and these three coloured phono/rca plugs on the other end, in order to connect the DVD player to the component (Y Pr PB) inputs - but I got no picture at all.

I was told (after I bought the lead mind) that you cannot convert RGB to YUV (apparently, Y Pr Pb is YUV?) without spending £145 on a converter box. Screw that I thought.

But since then, I have got very confused in wondering what the difference is between all this lot, so I need someone to tell me what is what, and why, and most importantly, in simple terms!!!!

So far I have been told (by a lot of people on the DigitalSpy forums) that RGB is better than component, as it has 4 pins (3 colour, 1 sync) whereas YUV only has 3 colour plugs. But then reading stuff on wikipedia, I get a whole load of stuff about YUV only being 2 colours, and one luma.... And then something about Y Cb Cr (what the hell is that?)

So, 1st question;

What is better : RGB via scart, or Y Pb Pr component - and why

2nd question;

what is the difference between : YPbPr component, YUV component, RGB component, and YCbCr component - and why?

3rd question - what exactly is YUV?

4th question - what exactly is RGB?

5th question - where does s-video fit into all this? (I was under the impression that s-vid (4pin DIN) was the same quality as NON rgb scart connections)

6th question - will I ever understand this? lol.....

Please please please help me lol....
 

Mr Incredible

Distinguished Member
There are better people in here than me to explain, but I do know how to point you in the right direction.

JS Technology are reknowned makers of video conversion equipment and they have written a neat article about this topic. Have a look here.
 

Matt_C

Distinguished Member
Okay, thats kinda helped me lol....

The order (1 = best to 4 = poorest) of video signal/deliverance I was told has been confirmed;

1) RGB (via scart)
2) Component (YPrPb/YUV)
3) S-video
4) Composite

What that doens't tell me tho, is how these differ in pic quality (ie, how much will you notice the difference between RGB SCART, YUV and s-vid - seein as s-vid is compressed, but then decompressed *demodulated) or what the difference in what *digital* Component video (YCbCr) and component RGB is - or indeed, tell me at all what these systems are....

So lets get some boffs in here to explain to me in nice easy "simple man" terms :D
 

Mr Incredible

Distinguished Member
In theory RGB is better than Component but I doubt if you would see any real difference in practice.

If on a 1 - 10 scale you rated quality perception with 10 being the highest, then RGB and component will be at 10, S-Video probably about 7.5 and composite about 3. IMHO of course!
 

Matt_C

Distinguished Member
So it's deffo worth going either RGB or componant over s-video? If so, that throws out using my AV amp for video switching then....

And am I right in guessing that non-RGB scart would be of a similar level to S-Video then? If this is the case, then I think I will have to change my DVD player for one with componant output on it....

Last q (for now lol) - would you notice a considerable difference viewing a freeview box in RGB scart instead of s-video?
 

Mr Incredible

Distinguished Member
You can get S-Vid implemented over Scart as well as RGB and composite.

One thought though, IIRC RGB over Scart only supports interlaced pictures and at "standard" resolutions. With a progressivescan DVD outputting component at say 720p, the component at that resolution will outstrip the standard defintiion RGB, assuming your TV can display 720p component signal. Sky HD (version 1) suppots both HDMI and component for HD transmission,

Perhaps I have just confused you and me now!!
 

andye2004

Active Member
Last q (for now lol) - would you notice a considerable difference viewing a freeview box in RGB scart instead of s-video?

Yes!

However, you don't need to spend £145 on a converter as you mentioned in post 1, all you need is an RGB compliant scart switch, less than £15, plug your DVD and freeview box into this and then plug that into the TV - hey presto, problem solved!

Here you go http://www.tvcables.co.uk/cgi-bin/tvcables/4-way-scart-switcher.html?id=rTSdU9BB, this will need manual switching but you can get auto switchers for about £30 just google auto scart switch.

EDIT : go to Conrad electronics and search for this part no. 350728 - 62, auto switch for £23 + £6 delivery.
 

Matt_C

Distinguished Member
Andy - that thought had crossed my mind yes, but it's simply yet ANOTHER box for switching! Which I don't really want - I already have a remote for the TV, another for the DVD, third for the Freeview box, fourth for the AV amp (from whaich ALL sound is coming from - nothing goes to TV) and a fifth for the vcr - a 6th for a switching box for scart would be a pain! Even more of a pain would be a cheapo one that requires me to get up and press a button everytime I wanna change a device!

Malice - yes, you have confused me a tad more lol.... But I *think* I see where you are coming from. My TV is a big CRT, and from another owners (and forum user) experience and testing, it can handle 768p via prog scan. That said, my DVD player ISN'T progscan....

By "implemented" I pressume you mean you can use S-Video from a scart socket? Thats one thing I did know you could do :)

I am thinking I might just keep an eye out for a Sony DVP-NS905V DVD/SACD player and replace my DVP-NS705V player, as it seems to be basically the same thing, but with component YUV output on it....

Another Q tho - this talk of prog scan - if 720p and upwards outstrips RGB scart - will it also outstrip YUV?
 

andye2004

Active Member
Look at the auto switch I posted details for, no remote / manual intervention required. it would just be like having the two things plugged straight into the TV - as long as you do not have them both running (switched on) at the same time that is.
 

davepuma

Distinguished Member
I already have a remote for the TV, another for the DVD, third for the Freeview box, fourth for the AV amp (from whaich ALL sound is coming from - nothing goes to TV) and a fifth for the vcr - a 6th for a switching box for scart would be a pain! Even more of a pain would be a cheapo one that requires me to get up and press a button everytime I wanna change a device!

Buy an all-in-one remote like a Harmony 525. The set up isn't perfect but once it is, it's a doddle to use. Just press one 'activity' button like "Watch TV" and voila, the remote will control all your equipment, switching it on in the right order, selecting the relevant inputs on AV receiver, switchbox and channel on the TV etc. The price is pretty cheap now but will probably drop once the newer model comes out.
 

baldrick

Novice Member
So component is only better as it can carry prog scan video?

I thought the general accepted order of quality was:

1. HDMI/DVI/Component
2. RBG SCART
3. S-Video
4. Composite
 

Matt_C

Distinguished Member
From what I have been reading on various threads on various forums/places on net, it's like this;

1. RGB (via scart)
2. Component (YUV)
3. S-Video
4. Composite
5. RF

HDMI and DVI aren't really comparable(sp) as they are completely different and digital in/outputs (like YCbCr component)
 

AngelEyes

Distinguished Member
1. HDMI/DVI/Component
2. RBG SCART
3. S-Video
4. Composite

This was my understanding of the quality tree for video connections. There seems to be some argument about HDMI/DVI and component as to which is best but I was pretty sure Component was far superior to RGB Scart... am I wrong?

Adam
 

Mr Incredible

Distinguished Member
I think for SD material RGB in theory has a wider bandwidth for carrying 3 x full channels of info, whereas component uses a "difference" algortihm.
 

hornydragon

Distinguished Member
So, 1st question;

What is better : RGB via scart, or Y Pb Pr component - and why
Depends on the native form of source RGB scart is actually RGB with composite video sync (RGBcvS)
2nd question;

what is the difference between : YPbPr component, YUV component, RGB component, and YCbCr component - and why?
YPbPr is an analogue colour difference singnal, Y Cb Cr is the same but in digital domain RGB has to be either RGBHV, RGBS, RGsB or RGBcvS no such thing as RGB exists
3rd question - what exactly is YUV?
Another name for YPbPr effectively
4th question - what exactly is RGB?
Red Green Blue signals (but wont work without a sync signal)
5th question - where does s-video fit into all this? (I was under the impression that s-vid (4pin DIN) was the same quality as NON rgb scart connections)
S-video is anothe r form of "component video signal" it sepeartes Luminance and chroma (colour and brightness/intensity)
6th question - will I ever understand this? lol.....
I do.................
 

AngelEyes

Distinguished Member
Interesting stuff, I now feel much happier using an RGB Scart auto switcher for my SD CRT TV. I was thinking about all sorts of component conversions etc.

I still need to get some sort of VGA to Scart conversion from my HTPC, any suggestions?
 

Mr Incredible

Distinguished Member
I'd look at perhaps a S-Video connection as it would just cost you the price of the cable? Although for me Sky RGB is slightly better than the S-Vid output, for your HTPC connecting to a SD CRT TV there may not be much of a difference that you'd want to spend much more money on a VGA - RGsB converter.

I think perhaps where there has been some doubt about RGsB vs Component is the fact that RGB is delivered over a Scart socket. Compared to a well matched set of 75Ώ component cables I think the slight technical superiority of RGB may get lost in the transmission!
 

Matt_C

Distinguished Member
Depends on the native form of source RGB scart is actually RGB with composite video sync (RGBcvS)

YPbPr is an analogue colour difference singnal, Y Cb Cr is the same but in digital domain RGB has to be either RGBHV, RGBS, RGsB or RGBcvS no such thing as RGB exists

Another name for YPbPr effectively

Red Green Blue signals (but wont work without a sync signal)

S-video is anothe r form of "component video signal" it sepeartes Luminance and chroma (colour and brightness/intensity)

I do.................

Right, so to recap - RGB scart is the best analogue video signal then? but the confusion with people saying it's not the best is cos it is output using a scart connector then? If RGB scart is simply RGB with a sync, what is RGB on it's own? I see a couple points later, you say RGB won't work without a sync, but how would you even get RGB + a sync without using a scart?

Onto YCrCb, does what you say mean that there is no such thing as digital RGB? Or is the PC VGA (os SVGA as it is sometimes called) basically the digital version of RGB+sync?

I think I understand S-vid now (read up on it) and I take it that it is better than the yellow composite video phono as it carries Luminance and chroma in two cables rather than one right? So where in the RGB SCART/Component/composite would you list S-Vid, in terms of PQ?

Lastly, what is "RGB componant", or is this a mis-name for componant cables (YUV) cos they have a red plug, green plug and blue plug?

Thank you so far guys - this has/is being very informative :)
 

Welwynnick

Distinguished Member
ALL video signals have to have sync signals.
These are to synchronise the lines and frames .
There are horizontal and vertical sync pulses.
Sync pulses can be embedded in the video signals, or may be carried as separate signals.

Composite - sync is embedded in the video.
S-video - sync is embedded in the luma video.
Component -sync is embedded in the luma (Y) signal.
RGB - complicated, but you have to get it right. There are various flavours:
RGsB - sync embedded in green video signal.
RGBS - V & H sync carried together on their own line. (like scart)
RGBHV - V & H sync carried on individual lines. (like VGA)

RGB scart is OK, but YUV has the advantage of using better connectors - RCA vs Peritel.

It's misleading to say RGB is better than YUV or vice-versa. YUV exists in some part of every video broadcast and storage chain, and is not in itself a limitation. HD DVDs don't store video in RGB and are none the worse for it. Any differences come from the difference in the performance of YUV to RGB transcoding circuits , and that is rather a second order effect.

Just as long as you don't use composite video or freebie cables!

Nick
 

hornydragon

Distinguished Member
Right, so to recap - RGB scart is the best analogue video signal then? but the confusion with people saying it's not the best is cos it is output using a scart connector then? If RGB scart is simply RGB with a sync, what is RGB on it's own? I see a couple points later, you say RGB won't work without a sync, but how would you even get RGB + a sync without using a scart?

Onto YCrCb, does what you say mean that there is no such thing as digital RGB? Or is the PC VGA (os SVGA as it is sometimes called) basically the digital version of RGB+sync?

VGA is analogue RGBHV at 800x600 res
There is digital RGBHV its called Digital RGBHV, Scart is a a cable standard we are talking video signals, RGB+Sync can be a 4 RCA cable thats not the limiting bit RGB scart uses a composite video sync, this is what limits the overall quality to an extent, as it means an interlaced only signal YPbPr can be progressive which can be better (at the same res progressive is better than interlaced)
 

Aitch_Kay

Standard Member
LOL !! I remember my old Economics classes ..... standardisation, economies of scale, easy consumer understanding, KISS etc etc - they were all meant the be the foundation of any successful company/industry !! What utter ******** !! :D

Seems to work on some things .... A4 paper, QWERTY keyboards etc ..... but sod all else !!!

Make all AV equipment have 6 HDMI slots, and include some decent quality HDMI cables with everything ..... job done !! :D
 

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