what are the lines of res. for tv?????

[alucard2050]

can someone explain to me what the lines of resolution are on a tv set? or is it the aspect ratio i'm looking for? i live in the US. if i capture at lets say 640x480, i get a better quality capture than 352x240 correct? what i want to do is capture at a format then when i encode it at full screen the picture won't have to do alot of cropping. i want the size of the picture to match up to the size of the tv screen if that makes sense.. thanks.....
p.s.-when i capture at 720x480, yuv, i get a big green bar on the bottom and on the side of the capture image......

[alucard2050]

stretch and crunch the picture is what i want to avoid if it makes sense......

[Bullworth]

Resolution on many modern TVs is 720 X 480. What you want is the aspect ratio of 4:3 for regular and 16:9 if you have a widescreen TV to make sure it fits on you screen properly.
The subject of capturing at at higher resolution i.e.: capturing at 640 x 480 and then shrinking to 352 x 240 is still debated. I find that capturing at a higher resolution and then shrinking gives me better results than to capture straight to the final size. Some people say it makes no difference while others say it does. I guess it's a matter of personal taste.
VCRs capture at 352 x 240 NTSC and S-VHS captures at even higher resolutions. I wouldn't recommend encoding the final video at 720 X 480 unless you have a DVD burner to encode at high bitrates because VCDs and their spawn can't handle 720 X 480 resolution very well at bitrates of 3000Mbits/sec. I already tried and as I was informed, and found out, unless you're encoding low-motion movies such as dramas you will get alot of macroblocks and artifacts. You can make X(S)VCDs at bitrates as high as 9000Mbits/sec with these resolutions but your time will drop to about 15 to 25 minutes per disc.
Anyways just though I'd toss that in. For NTSC you want at least 352 X 240 resolution minimum for quality and a 4:3 or 16:9 aspect ratio to fit your TV screen.

[kinneera]

For what its worth, my AIW-128 TV-out runs at 800x600 resolution. I don't really know if this has any correlation to TV resolution, but obviously it filled the screen correctly.

[alucard2050]

i am capturing now at 480x480 and my encode is at 480x480. but if i capture at lets say 800x600 or even mismatch to like 700x500, does anyone think that it would give a better picture if my encode is at 480x480? see what i'm saying is that if you look at the tv. its not a perfect square. its more of a diagonal shape. this is what i mean by stretching the picture. from a square shape encoded file to a rectagular shape........

[House de Kris]

"VCRs capture at 352 x 240 NTSC and S-VHS captures at even higher resolutions."

ALL VCRs, no matter how crappy, "capture" both fiels. In digital terminology, this would mean ---x480. The number of verical lines (or horizontal resolution) is a function of the bandwidth of the luma amplifiers inside the VCR (as well as the quality of the FMing of the luma signal).

To attempt to answer alucard's question, unlike VGA (which assumes square pixels) digitized TV stuff can (and usually does) have rectangular pixals. Hence a 480x480 capture for SVCD, which we would assume to be square based on the numbers, plays back as a full 4:3 TV screen. Or, did I misinterpret your question?

[kinneera]

Actually, pixelform differences don't account for that much difference. The real reason that 480x480 (should) work is that MPEGs encode a DAR value (display aspect ratio), which tells it how to display. In theory, any aspect ratio can be encoded at any other underlying resolution.

<font size=-1>[ This Message was edited by: kinneera on 2002-01-15 20:11:17 ]</font>

[alucard2050]

i think i might be lost here. let me try this again. if you look directly at your TV. the screen is more of a rectangle shape than a square shape. example-if you have a 25 inch set. the highth and the width are not both 25 inches long. its more like 20 inches high and 23 inches long or something like that, i just guessed but you get the picture. anyway, if you capture at 480x480 and encode to 480x480. the picture is a square box. if your resolution is lets say 720x240 then its a very long rectangle. i am looking for the size the box should be so there is a limited amount of stretching the picture when it is projected on the tv screen...........

[kinneera]

Well, you're confusing two difference concepts:

Resolution: the number of pixels used to encode the image horizontally and vertically. This data can then be displayed in any size or aspect. (Pixels are a relative, not fixed unit of measurement).

Display Aspect Ratio (DAR): the desired aspect ratio of the video. Typically 1:1 (VGA/computer screen), 4:3 (standard TV), 16:9 (widescreen TV), 2:35:1 (cinema movie).

You can encode video at 352x240, 352x480, 480x480, 720x480 or any other resolution you want, and it will fill your TV screen if you choose the 4:3 DAR. It would fill a widescreen TV if you chose 16:9 DAR. Hopefully you get the picture from there...

[alucard2050]

i am encodeing at 480x480 with aspect ratio set at 4:3 for a standard tv. then i select the full screen option instead of the keep aspect ratio option in TMPGE. if i select keep aspect ratio when i encode then the video played back on my tv doesnt fill the screen so i select full screen and that fills it but doesn't that stretch the picture????

[kinneera]

The arrangement method will affect how it deals with input and output aspect ratios that don't match. For example, if you select the keep aspect ratio option when your input is 16:9 and your output is 4:3, it will automatically letterbox the top and bottom to prevent stretching, which is desirable.

Other options may have the effect of cropping the left and right sides to achieve full screen when doing 16:9 to 4:3, and some will simply stretch (or in this case squeeze) the image, which of course is not desirable. No matter the case, the resolution is still an independent variable.

[alucard2050]

so in other words if i capture at 720x480 with the aspect ratio at 4:3 then encode it to 480x480 with the aspect ratio at 4:3, there wouldn't be any stretching of the picture since its going from 720x480 to 480x480??

p.s.-this should be the last question on this.........

[kinneera]

Yes. In some sense, your pixels' horizontal width will increase when the resolution is decreased to 480.