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186
 
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I`ve been swoting up on how DVD`s work and I was surprised to find that dvds only show colour at half to one quarter the resolution of the original image (witch now explanes why ITV1 looks so bad). so I was wondering why does colour sampling rates have to be cut by factors of 2? isn't there a more flexible and forgiving system in use?
harder,faster bet....er drat!
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Pentium
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The idea may have been formulated around the way the human eye works in relation to colour perception. We only need roughly one-third as much luminance accuracy in the colour content of a signal (the chrominance as it's officially termed) as in the luminance region. Analogue broadcast TV does the same thing. I guess that digital Freeview is probably doing the same thing as it uses MPEG-2 so is almost identical to DVD but at a slower bitrate. Domestic analogue VCRs rely on a similar technique to enable them to encode colour to magnetic tape efficiently at relatively low tape speeds.
The lowering of colour detail still allows for the same general crispness if the luminance signal still has enough bandwidth to play with. After all, you see just as much detail in a black-and-white film (potentially more actually) as you do in a colour film, so it obviously works. DVD would probably look much worse if it didn't do this to be honest.
One of the handy side-effects of bringing this topic up is that ffdshow can perform pretty much any image correction you're likely to need if you think that the master has minor deficiencies. That's why it's a wise move for the fussier of us to use a PC media centre as a DVD player. It gives you an enormous amount of control over the image quality in real-time once you've learned how to use ffdshow. 
Cheers, Slipstreem. 
System specs:
"Phoenix" / "The '43' Special" - 1.8GHz Intel C2D E4300 overclocked to 2.83GHz with ACF7Pro HSF on Volt-modded ASRock 775Dual-VSTA mobo (modded BIOS rev 3.10A, VNB=1.65, Vagp=1.8), 1GB Vitesta DDR500 RAM (2.5,3,3,7,1T @ DDR472MHz), Jetway ATI X1950Pro 256MB GDDR3 PCIe graphics card with modded AC Accelero X2 cooler dynamically overclocked to 650MHz GPU & 1.5GHz RAM. Powered by Hiper Type-M 580W PSU. Guess who likes overclocking on a budget. 
MP3 Encoding for Audiophiles
Fun MPEG-4 Encoding Race
MPEG-4 Playback Enhancement Using FFDShow
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186
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Last Login: 2 days ago @ 12:51:53
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I might look in to the FFshow app as Im going to be toying with VGA on my TV in the near future. hers another thing If green isn't sampled and is worked out later is it subject to the same colour sampling resolution as red and blue?
harder,faster bet....er drat!
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Pentium
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Last Login: Today @ 02:41:27
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| I don't have an answer to that one although, looking at the problem from a purely mathematical point of view, there's no logical reason why it couldn't be. I'd expect the noise level to be slightly higher as it would contain the dither and quantisation noise from the two other channels added together. I'm only guessing though. It's something I've never looked into. Cheers, Slipstreem.
System specs:
"Phoenix" / "The '43' Special" - 1.8GHz Intel C2D E4300 overclocked to 2.83GHz with ACF7Pro HSF on Volt-modded ASRock 775Dual-VSTA mobo (modded BIOS rev 3.10A, VNB=1.65, Vagp=1.8), 1GB Vitesta DDR500 RAM (2.5,3,3,7,1T @ DDR472MHz), Jetway ATI X1950Pro 256MB GDDR3 PCIe graphics card with modded AC Accelero X2 cooler dynamically overclocked to 650MHz GPU & 1.5GHz RAM. Powered by Hiper Type-M 580W PSU. Guess who likes overclocking on a budget.
MP3 Encoding for Audiophiles
Fun MPEG-4 Encoding Race
MPEG-4 Playback Enhancement Using FFDShow
Optimise ATI Image Quality with ATT (X1XXX Series under WinXP)
Boosting ATI Framerates with CCC (X700 on)
How good is the Arctic Cooling Freezer 7 Pro HSF really?
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286
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Last Login: 2 days ago @ 23:16:07
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| I'm curious. Why do you think this aspect of Mpeg-2 has any bearing on why ITV looks so bad?
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