CVBS vs RGB

[nig28]

Hi

My TV (Panasonic TX-28PB50) dosent seem to like RGB.

If I set it to CVBS this seems ok, it looks like a good picture to my old eyes. But on the scale componant> RGB>S-video>composite.

Where does CVBS come on this scale, and what does it mean in laymans terms.

Just bought a Packard Bell HDD/DVDR, seems ok so far.

Nigel

[Chris Muriel]

Comes bottom of the scale.

Cvbs = Composite Video Blanking and Syncs.
S-video is next - the colour part is sent separately from the luminance.
Then RGB (best of the 3 ) - where the colours are sent separately.

Chris Muriel, Manchester

[ismael-1986]

yup ill agree RGB is the best....

[Eiji]

Originally Posted by ismael-1986

yup ill agree RGB is the best....

after component

[ismael-1986]

HEHE well ok....

[Kirby]

I have noticed with TVs with component input the RGB doesn't seem quite as good through a scart as it is when an RGB enabled scart is the best option you have. I swear the RGB on my sammy isn't as good as my old CRT was however P Scan blows it clear away.

[red16v]

I see the old chestnut about the differences between of quality between 'component' (YUV) and RGB. In fact these days there is no difference. In the tv production centre all the equipment works on a digital format called SDI - this is a digital form of component (YUV) - the Y part being a full bandwidth 5.5MHz signal and the U&V signals being around half that bandwidth.

The only bit of kit at production centre that might still conceivably work in full bandwidth RGB is the actual tv camera but even then the RGB signals leaving the camera head are swiftly converted to SDI (ie, YUV).

So, the tv pictures that end up being received by your tv at home (no matter what the transmission method) will 'only' be to YUV quality and not RGB. Your domestic telly might well convert these decoded analogue YUV signals to RGB - but nothing is gained by it since the incoming signals have been bandwidth limited before they ever got to your telly (I suppose a crt requires RGB feeds to drive it but that is a matter of convenience rather than a design 'feature').

Having said that YUV pictures are of course a great deal better than composite of course! Regards, yt.

[aekostas]

Originally Posted by red16v

I see the old chestnut about the differences between of quality between 'component' (YUV) and RGB. In fact these days there is no difference.

Your analysis does not cover DVD input, does it?

[red16v]

Hi,
I must admit I did not consider DVD. However, the signal recorded on DVDs is mpeg(?). I suppose one would have to think about what are the basic constituent signals being fed to the encoder - hopefully there may be someone on the forum with some deeper knowledge of this and may be able to give a definitive answer - I suspect it too might be that the source signals are YUV - I'll be very interested in any informed replies. Regards, yt.

[Stephen Neal]

DVD is native YCrCb digital 4:2:0 MPEG2 on disc, just as digital TV is 4:2:0 YCrCb MPEG2 broadcast.

Digital TV is usually sourced from 4:2:2 YCrCb SDI infrastructure (though some VTRs are 4:1:1 or 4:2:0) and as others have posted the only RGB origination is in-camera, in-telecine and some graphics devices, all of which are swiftly converted to YCrCb for carriage over SDI.

Most DVDs will also be sourced from 4:2:2 SDI sources - like a VTR or a Telecine - however some may be from HD-SDI 4:2:2 YCrCb sources and down converted as part of the mastering, and some may even be 4:4:4 RGB sourced from a film scan.

There are penalties from multiple colour space conversions between RGB and YCrCb, but there should be little obvious difference at the receiver between RGB and YCrCb (digital) / YPrPb (analogue) interconnects - and most displays end up in RGB for screen driving so the conversion has to take place somewhere.

(NB YUV is not technically the correct terminology for digital or analogue component signals - it refers specifically to the weighted colour difference signals within a PAL encoder/decoder, just as YIQ refers to the rotated colour difference signals in NTSC gear. Better to refer to digital component as YCrCb and analogue component as YPrPb if you want to be clear about what signals you are referring to)