The image dimensions and aspect ratio are largely determined by the television standard you choose. If you look in the stores, many of the HD 16:9 TVs have different maximum image sizes. Some are 720 vertical, some are 1080, and others have odd sizes. Most of this confusion is due to the HD standards war. Standard def is 480i. But now comes along 480p, 720p, 1080i, and now 1080p.
But, generally, for 16:9 image aspect ratios the width in Pixels for HD should be 1280 and Standard Definition 940 pixels. The vertical is determined by the standard. If using 480p or 480i, then the vertcal size should be 480 pixels. If you're using 720p, then 720 pixels, and 1080i or 1080p should be 1080 pixels. The most common flavor of HD in the U.S. at the moment is 1080i.
It can all be quite confusing. And this is also why DVDs are generally made two ways... 16:9 or letterboxed and 4:3 full screen.
Now, on to your easier question about S-video.
The NTSC standards are the same regardless of which type of connector you use. The difference between Composite, S-Video, and Component are basically a function of bandwidth.
A Composite signal (like that found using a single RCA connector) crams all the color information (chrominance), the brightness information (luminance), and timing information onto a single pair of copper wires (a positive and a ground). With all this info crammed in there, there isn't a lot of room, so the colors bleed and the signals interfere with each other making for a pretty noisy picture.
S-Video (also sometimes called S-VHS as it evolved from those days on VCRs) improves the picture by separating the chominance and luminance and sending each on a different set of wires, thus allowing more bandwidth for each resulting in a cleaner, better picture.
Component goes a step further and sends the signals for Red, Green, and Blue on separate wires vastly improving the bandwidth for each color resulting in a much clearer picture.
When you hook up your computer to your TV using an S-Video connector (or any other analog connector for that matter) the graphics card is basically performing the function of a scan converter, though usually not as well as a dedicated device.
If you're using a graphics card designed for video editing that has S-Video out to a monitor, it's probably not scan-converting your computer screen, but sending out the video signal from the editing application in which everything we've covered in this thread will have been taken into account, either by you or by the editing application.
If you're sending out the signal over a firewire card, then you're using DV and need a device like a DV tape deck, or a DV camera to convert the fireware DV signal back into video.
THank you so much Racc. This is exactly what I needed to know. Thank you for being so very helpful!
It was my pleasure, guys.
In this world of converging technologies this kind of information is going to become more and more important not to mention confusing. Perhaps it will get better once standards have been decided.
Probably not, though.
Like I said at the beginning of this thread, I do this for a living. Making graphics for television/video, that is. So don't hesitate to ask if you have any video or TV related questions.
If I don't know the answer, I know a bunch of other people who probably do.
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