4:2:0, 4:2:2 and HD

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PopcornNMore

PopcornNMore

Thread Starter
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Mar 20, 2005
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Does anyone know what the numbers within 4:2:0 and 4:2:2 stand for?

Also are 4:2:2 and HD signals the same thing?

I really need to get myself a FTA PC card soon to receive these signals.
 
PSB

PSB

On vacation
Nov 5, 2003
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Some 4:2:2 signals are HD and some are not........

Your right! You are missing out BIG TIME on HD and 4:2:2 FTA

Some good reading here........

http://www.coolstf.com/
 
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PopcornNMore

PopcornNMore

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Mar 20, 2005
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Thank you very much Pete. Great site with lots of good information on DVB signals.
 
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lilyarbie

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Those Ratios refer to the color information that is digitally encoded into the signal. The higher the ratio, the better and richer the colors will be on the digital video. They don't necessarily refer to Hi-def programming. Some standard definition programming use the higher ratios for better color production. Also, some High def programming uses the lower ratio for the color information and some high def programming uses the higher ratio for better color production. The higher ratio needs more processing power from a cpu so that might be the reason why it locks up certain set-top FTA receivers whenever they're scanned in.
 
Tron

Tron

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May 6, 2005
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PopcornNMore said:
Does anyone know what the numbers within 4:2:0 and 4:2:2 stand for?

Also are 4:2:2 and HD signals the same thing?

I really need to get myself a FTA PC card soon to receive these signals.
As Lilyarbie said, this is the chroma sampling ratio in a component digital video stream. Basically, for each 4 times Y (luminance) is sampled, each color difference chroma channel (B-Y and R-Y) is sampled twice in a 4:2:2 signal. In a 4:2:0 signal, the first 4 times Y is sampled, B-Y is sampled twice and R-Y is not sampled at all. The next 4 times Y is sampled R-Y is sampled twice and B-Y is not sampled at all (so B-Y and R-Y are sampled alternately). Think of Y as green, R-Y as red and B-Y as blue, although that is not entirely accurate since DVB is not an RGB stream.

This ratio describes how the picture (luminance and chroma) are digitized into data. High end digital recording equipment uses 4:2:2 for high fidelity color reproduction. Some broadcasters use 4:2:2 DVB to deliver the best color possible in their streams. Such streams usually require a broadcast level DVB receiver to process, however it is possible for a PC to process the 4:2:2 streams fed by a PCI satellite card when using the proper CODEC software. Consumer DV camcorders use 4:1:1, and most DVB uses 4:2:0.
 
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global0

global0

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Jan 31, 2006
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PopcornNMore said:
Does anyone know what the numbers within 4:2:0 and 4:2:2 stand for?

Also are 4:2:2 and HD signals the same thing?

I really need to get myself a FTA PC card soon to receive these signals.

Tron has covered your first question very nice. I'd add that in a perfect world one would want the 4:4:4 sampling, but since bandwidth and processing are at a premium and because the human eye is less sensitive to color than intensity, the chroma components of an image need not be as well defined as the luma component, so many video systems sample the color difference channels at a lower definition than the brightness. This reduces the overall bandwidth of the video signal without much apparent loss of picture quality. The missing values will be interpolated or repeated from the preceding sample for that channel.

So, in regards to the second question: Not really/neccesarily. 4:2:2 sampling algorithm can be employed for HD transmissions depending on the method but it is not a mandatory requirement.

And for your final question: that makes the two of us ;) I need one of them cards too! Any suggestion for the card/brand?
 
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