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Author Topic: Vga - Video Is Shifted And Too Bright  (Read 373 times)

AnnaOlum

  • Guest
Vga - Video Is Shifted And Too Bright
« on: March 10, 2012, 11:13:18 AM »


Finally got my VGA mod to work. I combined the tutorials from JaredC01 and the internal sync tutorial from Xbox linux.
The improved tutorial from yaywoop did work too but the image wasn't really clear and was flickering a bit so I stayed with "my" method.

Unfortunately the output is too bright.
In 480p there's a thick white haze over the picture.
It's a lot better in 720p but the haze is still visible.
1080i doesn't work at all.

Is it possible to eliminate the haze?

Specs:
  • TSOP-flashed box with iND-BIOS 5003 (VGA)
  • Removed the DVD-Drive
  • SATA to IDE-Adapter with 250GB HDD





Edited by AnnaOlum, 10 March 2012 - 08:17 PM.


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AnnaOlum

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #1 on: March 12, 2012, 10:03:44 AM »


Any help please?




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xboxmods2977

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #2 on: March 13, 2012, 04:58:59 AM »


So you've stuck with the original LM1881 mod? IF so, try playing with the value of the resistor. Try some different value ones and see if that makes a difference.




Edited by xboxmods2977, 13 March 2012 - 01:26 PM.


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AnnaOlum

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #3 on: March 13, 2012, 07:12:29 AM »


Nah, I didn't use the LM1881 anymore - I used a 74HC14 to buffer the internal HSYNC and VSYNC. Then I wired the output from the 74HC14 to the VGA port.




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xboxmods2977

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Vga - Video Is Shifted And Too Bright
« Reply #4 on: March 13, 2012, 12:53:40 PM »


Ok, I read somewhere that your problem is another incompatibility with your monitor and your setup. While the H-sync and V-sync signals are almost "VESA perfect" using the buffer method, the Xbox RGB signals are a lower voltage than what standard VGA uses, which is why your picture appears faded. You will either need to build some sort of amplifier circuit for each of the RGB signals, or use a different monitor all together. I believe I remember reading somewhere that this can be fixed by building 3 simple transistor amplifier circuits. One for each color signal. I don't remember where I read it tho.




Edited by xboxmods2977, 13 March 2012 - 08:54 PM.


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AnnaOlum

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #5 on: March 13, 2012, 04:05:28 PM »


It's not really faded - it's like there's a white semi-transparent layer on the picture. The picture is too bright - not too dark!

BTW - the sync stripper method with the LM1881 did work but the picture was constantly jumping to the left a few inches and back again in higher resolutions. Would there be way to eliminate this? Was your answer with the resistors related to this problem?




Edited by AnnaOlum, 14 March 2012 - 12:52 AM.


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ldotsfan

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Vga - Video Is Shifted And Too Bright
« Reply #6 on: March 13, 2012, 10:14:51 PM »


I believe I remember reading somewhere that this can be fixed by building 3 simple transistor amplifier circuits. One for each color signal. I don't remember where I read it tho.

This article?




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xboxmods2977

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #7 on: March 14, 2012, 05:34:16 AM »


This article?
Nope, but that will work. Thanks L.
Anna, check out the diagrams that ldotsfan posted. There is an amplifier circuit there.

It's not really faded - it's like there's a white semi-transparent layer on the picture. The picture is too bright - not too dark!
The picture appears bright because in a television or monitor, you get dead white (brightness) combined with the RGB data colors (color). If the RGB data colors are not strong enough to match this white level, you get more white than color, causing the picture to appear bright.

BTW - the sync stripper method with the LM1881 did work but the picture was constantly jumping to the left a few inches and back again in higher resolutions. Would there be way to eliminate this?
Never had this issue. Not sure, but this could just be your monitor attempting to "auto-size" the image. Is this an issue with the HDTV? or CRT Monitor? or both?

Was your answer with the resistors related to this problem?
No. I was assuming you were having the brightness issue with the LM1881 method. It probably won't help the shift issue.




Edited by xboxmods2977, 14 March 2012 - 01:37 PM.


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AnnaOlum

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #8 on: March 14, 2012, 06:26:44 AM »


Never had this issue. Not sure, but this could just be your monitor attempting to "auto-size" the image. Is this an issue with the HDTV? or CRT Monitor? or both?
-
No. I was assuming you were having the brightness issue with the LM1881 method. It probably won't help the shift issue.


With the LM1881:
The issue only occurs when i hook it up to my HDTV. No problems on CRT or LCD monitors.
And then only in 480p, in 720p and 1080i it works but the picture jumps around.

With the 74HC14:
The same as above but here it doesn't jump around.
In 720p the haze isn't really that bad but still annoying. 1080i doesn't work at all.




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xboxmods2977

  • Guest
Vga - Video Is Shifted And Too Bright
« Reply #9 on: March 14, 2012, 06:50:44 AM »


It sounds to me as if your HDTV won't be happy, no matter what method you use. I would stick to using component cable for the TV and use your Xbox VGA with your PC monitors.




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