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31 March 2012, 15:20   #530
Schoenfeld
electricky.

Join Date: Jun 2010
Location: out in the wild
Posts: 1,243
Quote:
 Originally Posted by Retrofan Ok, so let's think in the 1600x1200, 62.5Hz Pal using Dvi and the MKII in a future.
Now you're randomly mixing numbers.

Quote:
 Originally Posted by Retrofan Which is the resolution without it and using the rgb Scart?
Through Scart, you can normally only transfer 15kHz line frequency modes. RGB-Scart is seldomly supported by modern TVs, and it has nothing to do with Indivision AGA MK2.

Quote:
 Originally Posted by Retrofan Well, perhaps a HD video could show it.
Probably not. Please read a little about how a video picture is generated, and how much data you have to move around in order to get a stable picture. Only if you do the actual math, you'll be able to understand what pixelclock and data rates mean in the real world.

Quote:
 Originally Posted by Retrofan EDIT: Sorry, my actual resolution using rgb scart is 1372x544, 50Hz.
This may be true for other devices, but not for the Amiga, and it has nothing to do with Indivision AGA MK2.

Quote:
 Originally Posted by Retrofan So the point to compare is that of 1600x1200, 62.5 Hz. That's what I wanted to know. Thanks.
OK, so let's do the math: First of all, don't mix the 62.5Hz of Indivision AGA MK2 with a standard VESA screenmode - better use the standard target frequency of 60Hz:

1600 pixels per line
plus 64 pixels front porch
plus 192 pixels actual sync pulse
plus 304 pixels Back porch
------------------
total: 2160 pixels per line

1200 lines per screen
1 line front porch
3 lines actual sync pulse
46 lines back porch
----------------
total frame=1250 lines

Total pixels per screen:2160*1250=2.7 million
total pixels per second at 60Hz: 2700000*60=162 million

Result: You need to output the picture at 162 MHz pixel clock. This is more than the 135 MHz currently verified on Indivision AGA MK2. Conclusion: 1600x1200 is not possible. Got it?

Jens

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