Video Connections Made Confusing

video connectorsVideo connections sure are confusing. I have a degree in electrical engineering from an Ivy League institution, and I'm befuddled by it all. I feel sorry for you mere mortals out there.

I'm building a media PC from scratch, and I'm trying to get a good video display. Mind you, at this point, I'm not trying to play video media. I'm just trying to wring the fuzzies out of the display when I run the music player or web browser.

The computer has VGA, S-Video, and DVI video outputs. The television has composite, S-Video, component video, and HDMI inputs. You'd think that with all those choices, there would be some way to insert tab A into slot B and make it all work.

The first and obvious choice is S-Video–both units have that. In fact, as I reported in that prior article, S-Video works. Unfortunately, it doesn't work so good. You may be surprised to learn that S-Video has the same crappy resolution as the bottom-of-the-line composite video connnector. Both do 480 interlaced scan lines, The difference is that S-Video separates out the signals so it's a crisper 480i. That means with S-Video, I'm trying to display 800x600 on 480 interlaced scan lines–no wonder it looks like crap.

I wanted to do better, but S-Video is the only connection the two had in common. The "high def quality" component video TV inputs would be ideal, but the computer doesn't have matching outputs.

After some web searches I found an adapter jig that would connect up to the DVI connector of an ATI video card and produce component video. My on-board video is ATI, so I thought this would be a shoo-in. All I needed was this one cheap adapter and it was component video all the way.

Well, not quite so fast Poindexter. When I got the adapter it wouldn't fit. That's when I learned that there isn't just one kind of DVI connector. There is DVI with digital video signals (DVI-D), analog video signals (DVI-A), and a combination of the two (DVI-I). Moreover, there are single-link and double-link DVI-D connectors (double has more pins). This adapter jig was made for a DVI-I connector, and it used the analog outputs to produce component video. My computer has a DVI-D connector with no place for the analog pins to fit into. That's why the connector wouldn't fit.

So, it was back to the drawing board. I found devices that convert DVI-D to component video, but at over a hundred bucks that didn't make sense. I thought about getting a DVI-D to HDMI cable, but they aren't cheap. Moreover, the A/V receiver I have my eye on has component video inputs but not HDMI. I really want to get component video.

I concluded there is no reasonable way to go from digital DVI to analog component video. But what if I could do analog all the way? That got me thinking: computer VGA is an analog video signal. Is there some way I could get component video from a VGA output? Unfortunately, not easily. The signals aren't compatible. VGA uses RGB (red, green, blue level) signals, while component video is YPbPr. It appears that at least some ATI adapters can be kludged to produce component video signals on the VGA connector. Even if my hardware can support that, I'm not sure if the Linux fglrx video driver can. I haven't ruled it out, but it's a longshot at best.

I'm not sure if I'm getting any closer to a solution, but I'm getting a heck of an education on video interconnections.


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avoid this problem by getting a good mobo

You have a few options when connecting an HD quality HTPC.

Solution #1: (no Blu-ray HDCP compliant connections)
get an HDTV with a DVI-D connection. (my sharp has it LC-42D72U, but I think there are a few others out there)
get a motherboard that has HDMI, DVI-D, and a regular analog RGB/VGA connection (Asus P5Q-EM)
get a video card that comes with at least an s-video out and an included s-video to component adapter

Solution #2: (with Blu-ray player drive in HTPC)
here you need to have all HDCP compliant devices (HDMI-out ports and your display have to be HDCP compliant or blu-ray movies will show you an error message and you will have to use an analog connection which only displays up to 1080i not 1080P.

For an HTPC, if your case doesn't have much room inside, just get a motherboard with HDMI-out and HDCP compliance. (Asus P5Q-EM)

For an HTPC with tons of room inside: get a Nvidia 9 series card with an HDMI out. You should also get Nvidia's Pure video HD encoder (I think it comes on the included video card software)

The last two options will show the full HD 1080P quality of Blu-ray movies and are the easiest way to connect your HTPC to any HDTV.

Now if there were only some good HDMI-in capture cards that could capture full 1080i signals...

re: Video Connections Made Confusing

If you find a way to do this, let me know. I have an Asus Pundit (original version) and I want to hook it up with component video. I found the pinouts to do it here with CAT5 cable (interesting) but it says it may not work with all video cards: