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Oswald
Registered: Apr 2002
Posts: 5086 |
VIC and the odd/even fields
okay this is getting confusing for me now. in another thread on lemon64 groepaz says that the vic does always display the same field, but it doesnt matter if its odd or even, and it lights up both the odd/even lines.
some1 can tell me:
- does vic use odd or even or dontcare lines?
- what does the term field mean from the tv electronics viewpoint?
- how does the vic only light up the odd (forex.) lines on the tv screen, and a little bit from the other ones?
- are there really 2 modes in the tv electronics for odd / even fields
- why does computer graphics flicker a hell more lot while "normal" tv screens looks as steady as my ass?
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ptoing
Registered: Sep 2005
Posts: 271 |
meh |
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chatGPZ
Registered: Dec 2001
Posts: 11360 |
Quote: you mean the "looks like" part?
yes what else? the mask obviously limits the "analogness" (uhh) to some degree |
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MagerValp
Registered: Dec 2001
Posts: 1074 |
Understanding how displays work is of course useful, and is a prerequisite for developing some effects. For example, our beloved 0.5 pixel scrolling that, regardless of what Oswald believes, generates a genuine resolution increase. |
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Oswald
Registered: Apr 2002
Posts: 5086 |
mager, regardless of what you believe I am right. (just to copy your argue style:) |
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MagerValp
Registered: Dec 2001
Posts: 1074 |
You could take a hint from the fact that the people sitting here explaining how CRTs work, are the same people that say that 0.5 pixel scrolling works.
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chatGPZ
Registered: Dec 2001
Posts: 11360 |
Quote: You could take a hint from the fact that the people sitting here explaining how CRTs work, are the same people that say that 0.5 pixel scrolling works.
keep me out of that kthxbye :) |
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Nightlord
Account closed
Registered: Jan 2003
Posts: 131 |
ok I have a question. I see a contradiction between what Groepaz says and what Magervalp says about Chrominance being half resolution.
So there are 576/2= 288 scan lines in one frame (between 2 v-syncs). For each 288 scanlines, The corresponding part of the signal starts with h-sync, then color burst, then video_info. My understanding was that the low freq amplitude of video_info is luminance and the color gets modulated and added to the signal in a higher freq smaller amplitude sinusoidal whose amplitude determinas "saturation" and whose phase determines "hue".
From what I understand, Groepaz is saying there are 288/2=144 lines in each frame that has this modulated color info and 2 consecutive scanlines in same frame use the same crominance.
Where as Magervalp refers to "horizontal resolution being half". thus two "pixels" (thinking of pixel as a part of crt tube where the beam covers in 1/50/288/720 seconds) next to each other share the same chrominance but can have different luminances. This way all 288 scan lines in a frame has different color info modulated in them.
Do I understand you guys correctly? If yes which is true? I was thinking Magervalp's statement is true, but I am not 100% sure
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chatGPZ
Registered: Dec 2001
Posts: 11360 |
chromincance has lower resolution in both dimensions :) in X its valid for more than one pixel, in Y it "drains" down the display due to the delay line. |
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Nightlord
Account closed
Registered: Jan 2003
Posts: 131 |
ok so all 288 lines between 2 v-syncs have different chrominance, right?
The "draining" you refer to confuses me though... Isn't that true for Y as well? |
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chatGPZ
Registered: Dec 2001
Posts: 11360 |
Quote:ok so all 288 lines between 2 v-syncs have different chrominance, right?
yes
Quote:The "draining" you refer to confuses me though... Isn't that true for Y as well?
no, thats only done for chrominance (and only on PAL *afaik* - ntsc works a bit different). |
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