[mythtv-users] intel 845G - vga to scart

marek mark_kiddy at wp.pl
Tue Aug 28 11:41:11 UTC 2007

You are partially right :
intel doesn't output csync so I recreate it (with simple one transistor 
circuit - the same cable for radeon & intel) .
real problem is the intel linux driver for xorg (and i think hardware too)
intel's min pixel-clock is 25MHz - so interlaced modelines can't be 
simply adapted from radeon
eg. on radeon I use now 
    Modeline "736x575i" 14.16 736 760 824 904 575 580 585 625 interlace 
-hsync -vsync,
with excellent results but this modeline is rejected on intel 
(pixel-clock too low) so I must use sth. like this  :
    ModeLine "PAL_2" 28.02 1440 1488 1632 1800 575 580 585 625 -hsync 
-vsync interlace
(which is adequate of 720x576 50Hz interlaced)

result is little strange but it partially works.

problems :
picture is vertically doubled
while vsync & hsync looks properly on oscilloscope (with proper freq's) 
- picture isn't stable horizontally
(random horizontal picture oscillation from left to right, cursor in the 
same time oscillates from right to left about the same distance, but  
all of these without breaking hsync - only picture moves irregularly, 
vertically picture is stable)

i think this is driver issue (calculating horizontal line length or PLL 
doesn't lock)

I think that I said it clearly. Any ideas ?
Marek K.

Andy Burns pisze:
> On 28/08/2007 07:57, marek wrote:
>> does anyone tried this (intel 845G - vga to scart cable) with any luck ?
>> now i'm using radeon 7000 AGP with excellent results but i need one more 
>> PCI slot (which is shared with AGP)
> I don't think the modelines would be a problem, but unlike the Radeon, I 
> don't think the Intel chipset can output c-sync, so you'd need a 
> h/v-sync to c-sync combiner circuit, such as
> http://www.electronics-lab.com/projects/pc/012/
> http://www.tkk.fi/Misc/Electronics/circuits/vga2tv/psergio_circuit.html
> http://www.tkk.fi/Misc/Electronics/circuits/vga2rgbs.html
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