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Author Topic: The Theory Behind the Xbox VGA Converter  (Read 34 times)

Xbox-Scene

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The Theory Behind the Xbox VGA Converter
« on: April 20, 2006, 06:49:00 PM »

The Theory Behind the Xbox VGA Converter-- Posted by XanTium on April 20 20:13 EST
From xbox-linux.org:

Quote

Steve Gehlbach, the designer of the first Xbox HDTV to VGA converter, describes the theory behind his design in the article Maximizing Op Amp Summing Power on his website.

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Sloppy Fat Dump

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The Theory Behind the Xbox VGA Converter
« Reply #1 on: April 20, 2006, 07:34:00 PM »
1st comment!!!

Yay.

One thing I would like to ask is the difference between VGA HD and the standard HD cords.  Couldn't really completely answer that by the artical.
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Mr Ed

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The Theory Behind the Xbox VGA Converter
« Reply #2 on: April 20, 2006, 07:46:00 PM »
QUOTE(Sloppy Fat Dump @ Apr 20 2006, 06:05 PM) View Post

1st comment!!!

Yay.

One thing I would like to ask is the difference between VGA HD and the standard HD cords.  Couldn't really completely answer that by the artical.


Uh, the VGA uses a 15-pin D-Sub connector.  The HD uses three RCA connectors.  sleeping.gif
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ErichMoraga

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The Theory Behind the Xbox VGA Converter
« Reply #3 on: April 20, 2006, 08:36:00 PM »
QUOTE(Sloppy Fat Dump @ Apr 21 2006, 02:05 AM) *

1st comment!!!

Yay.

One thing I would like to ask is the difference between VGA HD and the standard HD cords.  Couldn't really completely answer that by the artical.

I guess you were more concerned with having the 1st reply than actual reading the article.

Here is an example of where the author explains one of the differences:
"A few comments are appropriate regarding the design of Figure 4. The sync separator used is the Genum GS4981 instead of the more commonly available LM1881. The reason for this is the horizontal output. The LM1881 does not produce true horizontal drive, i.e., a horizontal output without vertical sync included. The VGA standard requires this, and some VGA monitors will not sync or set the reference black level properly without true horizontal drive."

The significance of the article is that a *better* VGA adapter design was made and fully documented/explained.  I'm sure most readers are interested in seeing if there are tangible differences in video quality as well.

-Erich
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Sloppy Fat Dump

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The Theory Behind the Xbox VGA Converter
« Reply #4 on: April 20, 2006, 10:05:00 PM »
Um, for the average Joe... including myself... that makes no sense.


Did you not read what I wrote?  I said that I couldn't find anything in the artical that completely answered the question.  Now, sdfu.  Thanks.
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ErichMoraga

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The Theory Behind the Xbox VGA Converter
« Reply #5 on: April 21, 2006, 07:09:00 AM »
QUOTE(Sloppy Fat Dump @ Apr 21 2006, 04:36 AM) *

Um, for the average Joe... including myself... that makes no sense.
Did you not read what I wrote?  I said that I couldn't find anything in the artical that completely answered the question.  Now, sdfu.  Thanks.

Frankly, the question you asked, "One thing I would like to ask is the difference between VGA HD and the standard HD cords. Couldn't really completely answer that by the artical." isn't the best question (or is just phrased a little wrong).  A better question to ask is:

What makes this VGA adapter different than the other VGA adapters out there already?

As far as telling people to "sdfu" (or STFU to most people), well, that just speaks volumes for you.  I don't think the article was intended for "the average Joe" ...

-Erich

This post has been edited by ErichMoraga: Apr 21 2006, 02:10 PM
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twistedsymphony

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The Theory Behind the Xbox VGA Converter
« Reply #6 on: April 21, 2006, 07:16:00 AM »
This is really interesting,

I just started a project the complete opposite of this last week. Creating an RGB/VGA to YPbPr converter for both my Saturn and Dreamcast so that I can use a single input type across all my devices (component video).

The inverse (component to VGA) is a little more complex but the same basic concept...

It would have been nice to have seen this article last week before I went through all my calculations... ah well now I have something available to help double check them.]

BTW if you want to attempt a converter project like this, definitly order your opamps from Intersil. I ordered some samples from them and the guy called me up and even gave me some tips on the circiut design (IMG:style_emoticons/default/beerchug.gif)

http://www.intersil.com

This post has been edited by twistedsymphony: Apr 21 2006, 02:19 PM
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Interloper

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The Theory Behind the Xbox VGA Converter
« Reply #7 on: April 21, 2006, 03:37:00 PM »
QUOTE
The inverse (component to VGA) is a little more complex but the same basic concept...


Indeed, requiring a transceiver in most cases
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veeper

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The Theory Behind the Xbox VGA Converter
« Reply #8 on: May 03, 2006, 07:23:00 AM »
I assume there is noone on the forum yet who tried to make the homebrew-transcoder himself? For me it seems better than the hombrew vga because it is widely more compatible (eg. no special bios) yet it is much cheaper than any commercial product.
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