Arch Linux

billy

Member

From: Slovenia

Registered: 2006-09-13

Posts: 164

Vga -> Hdmi ?

I want to connect my old geforce 2 mx400 card to a new hd-ready tv. For now it's connected over the s-video on the card and scart on the tv. the biggest resolution i can get is 800x600 and it has black border around it .  I want to try to connect VGA to HDMI, but is it gonna work? I have seen only VGA to DVI and DVI to HDMI adapters, and because of that i'm in doubt that this will work. Would it work just by combining together an VGA to DVI and DVI to HDMI adapter? Or am I better off buying a new (AGP) graphics card?

iphitus

Forum Fellow

From: Melbourne, Australia

Registered: 2004-10-09

Posts: 4,927

Re: Vga -> Hdmi ?

VGA is analog, DVI is capable of analog. Hence VGA->DVI adaptors exist for analog.

DVI is also capable of digital, and AFAIK HDMI is digital only. So those adaptors would only do digital, meaning you can't string them together.

My HDTV has a VGA in port, check for that -- otherwise you'll need to pay for some sort of external box which will take the analog VGA signal and convert it to digital for HDMI.

James

cry0x

Member

Registered: 2007-04-11

Posts: 91

Re: Vga -> Hdmi ?

VGA is analog, DVI is capable of analog. Hence VGA->DVI adaptors exist for analog.

DVI is also capable of digital, and AFAIK HDMI is digital only. So those adaptors would only do digital, meaning you can't string them together.

My HDTV has a VGA in port, check for that -- otherwise you'll need to pay for some sort of external box which will take the analog VGA signal and convert it to digital for HDMI.

James

Not necessarily true. DVI-I is capable of digital and analog, but DVI-D is only digital. No DVI-D to VGA adapters exist.

HDMI is only digital. You cannot do HDMI -> VGA without a digital to analog converter.

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Who is this doin' this synthetic type of alpha beta psychedelic funkin'?

billy

Member

From: Slovenia

Registered: 2006-09-13

Posts: 164

Re: Vga -> Hdmi ?

my tv doesn't have vga input, it has only scart, hdmi and component input. And since vga to component adapters are very expensive, I think I'll buy a new graphics card.
thx for your replies.

JoeBob

Member

Registered: 2007-01-25

Posts: 2

Re: Vga -> Hdmi ?

Interestingly enough, calling YPbPr component video is a misnomer since there are many types of component video, of which VGA is one (also known as RGBHV).  And since both YPbPr and VGA are so similar it's not too hard to wire up a converter yourself.  VGA uses 5 wires, one for the Red, one for the Green, one for the Blue and two for synchronization.  YPbPr only uses 3 wires, one for luma, one for the difference between blue and luma and one for the difference between red and luma.  The main differences between VGA and YPbPr are that YPbPr does not send green, and that YPbPr does not have horizontal and vertical sync wires. Both of these are easy to get around of actually, since you're sending luma and the difference between luma and red, as well as the difference between luma and blue, if you subtract the from luma both the differences between luma and red and between luma and blue, what you are left with is the difference between luma and green, and in component video used in televisions, the sync is on the luma (Y) wire as well.

Simply put, summing R, G, and B would give you luma, and then subtracting B and G from R would give you Pr, and then subtracting R and G from B would give you Pb.  Adding the synchronization to Y is slightly more complicated, but can still be done with only a few components.  Try searching google for VGA transcoder, VGA YPrPb transcoder, or DIY VGA transcoder or something to find a circuit someone has already built, there are lots out there.

Oh, and I just realized I am dumb.  I just reread your post and you said you had a SCART connector.  I live in Canada and SCART is usually used in Europe so I might not be right, but I seem to recall SCART on televisions using RGBS, but I'm not 100% sure. RGBS would use a wire for Red, a wire for Green, a wire for Blue, and a single wire for synchronization.  In this case you would only have to convert the sync being on H and V to simply being on S, which is is even easier than the way I described above. So yeah, sorry for the long winded reply, but make a search for a transcoder circuit from RGBHV to RGBS and I'm sure you'll come across something, it can  be done with few gates and a transistor or two, so look for something relatively simple.

Oh, and yes you can buy these transcoders, but they're usually over a $100 for only a few dollars worth of parts, and since it's so simple to build it can just be thrown on a prototype board instead of making a PCB for it.  Well, I hope that helps, take care.