720p? 1080i? I'm still confused. (1 Viewer)

[Drew Salter]

I'm still very confused as to what these definitions are for.

Obviously they relate to resolution, but how? Are they lines or what? If so, how does it relate to horizontal resolution?

I know these are newbie questions, but I read through the HT basics forum as well as the cliff notes thing on powerstrip and I'm still confused.

My ultiate goal is to get a great picture on my Sony 51 widescreen. Has DVI.

Can someone point me to a tutorial on the basics of resolution as it relates to DVD, HDTV and computer resolution?

Thanks.

Drew

 

[Ken Chan]

They are scanlines. Standard HD resolutions are 1920x1080 and 1280x720 (width by height). If you do the math, you'll notice that these are 16:9, which means they use square pixels, like a computer. Shorthand is 1080i and 720p; the p is for progressive, which means that the entire frame is updated every time, while i is interlaced, which has disadvantages, especially with lots of motion. But on still images, you get a lot more detail. ABC uses 1280x720; CBS and NBC use 1920x1080.
Another digital, but not high definition resolution is 704x480, also progressive, so it's 480p. The image is still 16:9, but the pixels are not square. Fox uses this.
DVDs are usually 720x480, but can also be 704x480. The pixels are the same shape; with 720 you get eight more pixels on each side, which are usually hidden by the overscan of your TV anyway. DVDs are interlaced, 480i.
Because of the way progressive film is converted to interlaced video, you can often use a progressive DVD player to "recover" the progressive frames of a movie. So DVD can look as good as Fox, but nowhere near the other networks' HD.
When you play a DVD on your computer, the 720x480 is usually upsampled to 960x540 (square pixels again).
//Ken

 

[Drew Salter]

Thanks for the reply. That clears up the reolution issue. I didn't realize that it was just shorthand.

So what I'm looking for to connect is a video card that can output DVI at 1080i. The 1080i can be achived through PowerStrip I imagine, so I just need DVI.

Do most video cards advertise this? How would I find out which do and do not support DVI output?

Thanks again.

Drew

 

[Chris Tsutsui]

I think all video cards will specify if it has an additional DVI output. You can also look at the picture of the card and see if it has it.

Most of the recent radeons and geforce cards should have an option with DVI.

 

[MattVolk]

Most of the ATI cards can do 1920 x 1080 over DVI. I was looking into getting a AIW 8500DV and it appears to be able to do all of the DTV formats.

One interesting fact (from other posts on HTF) is the DVI port on HDTVs don't let you watch DVDs at resolutions higher than 480p. If you use a component video connection you won't have this restriction. The component dongle for ATI cards (8500 and newer) is only $29.95.

 

[Drew Salter]

That is kinda wierd about the DVI not allowing higher resolution. I'm kinda partial to nVidia right now, but I may make the jump over to ATI.

Does anybody know, if one runs output fro teh DVI and Copnent on the card, will it allow output on both formats?

Is the picture any worse/better with DVI or Component?

Drew