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[Foe-hammer]

Those of you who use the vga bios, do you use the higher res settings (720p and 1080i)?

The vga bios can do these higher resolutions, but the problem i get is the colors ratio is all off (too much purple and red), and the picture is extremely dark; looks just the same as when an older x2vga (transcoder) is hooked to a newer xbox with a focus chip.  Under these conditions, it is not feasible to play.

This has been a problem since pixel8 released his vga bios over 2yrs ago.  And because all other vga bios are just pixel8's vga bios, with some things added, they all have this problem.  Pixel8 must have lost interest in his vga bios project, because he has not updated it since the day he put out the beta release.

I know what the problem is with the vga bios that make them do this in the higher res settings, but because of my lack of knowledge, i do not know what i'm doing to fix it.

Here is the problem:

720p and 1080i using a "tri-level" sync, meaning the sync goes negative and then positive. Most monitors will interpret this positive sync tip as color info and sample the black reference level incorrectly. In 480p the sync pulse in the video is "bi-level" meaning it only goes negative. I expect there may be a way to fix that with the VGA BIOS if it is designed to switch the video encoder to use "bi-level" syncs for those video modes.

I have discussed this issue before, and am hoping someone with the know how would please take a look at this.

[Foe-hammer]

QUOTE(fahrenheit @ Apr 22 2005, 11:40 AM)

I use Junkmonkey's VGA BIOS, but don't use those resolutions because of the colour. I use an MS HD pack and attach to the BNC connectors on my monitor.

[dethbox]

I use the same setup as well, HD pack  + BNC. I have no problems with any application or game in any resolution. The only problem  ive ever had with this setup, the green wash effect. Most games work fine, some don't.

[Foe-hammer]

QUOTE(dethbox @ Apr 25 2005, 09:07 AM)

I use the same setup as well, HD pack  + BNC. I have no problems with any application or game in any resolution. The only problem  ive ever had with this setup, the green wash effect. Most games work fine, some don't.

[The Zep Man]

QUOTE

720p and 1080i using a "tri-level" sync, meaning the sync goes negative and then positive. Most monitors will interpret this positive sync tip as color info and sample the black reference level incorrectly. In 480p the sync pulse in the video is "bi-level" meaning it only goes negative. I expect there may be a way to fix that with the VGA BIOS if it is designed to switch the video encoder to use "bi-level" syncs for those video modes.

I think this is true for the biggest part. My monitor has got a setting which gives the options 'forth' and 'back'. Look for more about BIOS-specific things in this thread.

[edit]
A sync seperator (LM 1881?) maybe COULD solve this problem. I thought that one of the outputs of the LM 1881 was a 'clean' (non-SOG) green signal? What if you only send that one to the monitor instead of directly sending the SOG-signal to the sync seperator AND the monitor?

[edit2]
Data sheet of the LM 1881 N. Guess I was wrong. Still, a sync seperator could help. I just don't know how it responds to the signal of 720p (or higher).

I just ordered two of those chips. Let's find out!

[TB_88]

Nope I use sync seperater and I stil get pink in 720p...
I don't understand that the bios developers don't work on this...
It's for em more important then let's say reset on eject fix.

[The Zep Man]

QUOTE(TB_88 @ May 26 2005, 01:38 PM)

Nope I use sync seperater and I stil get pink in 720p...

[DarkLegion]

Don't know if this is the same problem,but with DIY dreamcast vga you must run the H/V syncs through a resistor or it will result in distorted colours of pinks,blues and greens which seems to be an effect that is seen when the sync levels are too high for a particular monitor.I cannot remember the value for the dreamcast (and it will likely be different to the xbox) but its an area that should be explored.I'd check it out myself,but I can't use 720p on my monitor in any case.