ASPECT RATIOS Please explain?

[jbear]

This is another one of my dumb questions, but can anyone tell me the ratio to use for plain olf 4:3 video?
Ive been told many different numbers from the sublime to the redicules. (From all different
tech support people and have never gotten an answer that makes sense.) There is of course the one we all see 720x480, and 640x480and there was one support person who told me 780x440!.
One of the recurrant problems I have had with this is that each software program seems to have there own little system to figure it. I know it is a problem with square vs rectangular pixels. (I had a guy at "The Ranch" give me a two hour dissertation on the problem. . .at least I think it was two hours. . .I just nodded off.)

Take a somewhat limited capture prog like GoCap (It's a small utility from Plextor) Just to get the capture started. I have the choice, 640x480 or 720x480. I want to know what to use so that my tv (?) will have the correct image proportions. And as dumb as it sounds (again) i've hever had an answer.
I deal with 70mm interpositives that I scan onto a hard drive. The scanner that I have been using for this is (I think) from Panavision. I have know idea where the software came from, but it's pretty hard-wired to the scanner (it also adds frame numbers, which for me is critical) There is no chance for me to change it the aspect but the scans are always spot-on. But I'm trying to get hundreds of miles of tape converted to something I can use. (And I REALLY know when the ratio is off.)

I'd love to hear some feedback.

Thanks jbear

[Bodyslide]

From the Glossary to the Left. Hope this is a good Starting point:

Aspect Ratio
The width-to-height ratio of an image. A 4:3 aspect ratio means the horizontal size is a third again wider than the vertical size. Standard television ratio is 4:3 (or 1.33:1). Widescreen DVD and HTDV aspect ratio is 16:9 (or 1.78:1). Common film aspect ratios are 1.85:1 and 2.35:1. Aspect ratios normalized to a height of 1 are often abbreviated by leaving off the :1.

[lordsmurf]

4:3 .... the image is 4x across and 3x up&down
4x and 3x of what, you ask? Doesn't matter.

take 6 inches ... 4x6 and 3x6 = 24 inches across by 18 inches

Traditional tv signals have a 4:3 rectangle shape.

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Now with widescreen, you can do all sorts of other aspects. 16:9 is really long, a skinny/flat rectangle.

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And then we can do fractions too, this is the fun part ... 4:3 is the same as 1.33:1 ...... basic math

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You have film. Pull out a ruler, measure a frame, do the math, figure out your aspect ratio of the source.

[jagabo]

The frame size is independent of display aspect ratio with many codecs. I assume your 640x480 capture is 4:3 with square pixels, and the 720x480 is 4:3 with non-square pixels. If you're going to DVD then use 720x480 since that matches one of the valid DVD frame sizes.

[manono]

The guy that told you 780x440 wasn't so far off the mark, as it's 1.77:1. If you plan to do this for 16:9 DVD, then resize to 720x480 and encode. I would have suggested something slightly different, but he's not really wrong.

However, I agree with jagabo. If the destination is a 4:3 DVD, then 720x480. If for AVI, then 640x480 if this thing is fullscreen.

[scardi]

Hello Jbear
Have a look at this thread:
https://forum.videohelp.com/viewtopic.php?t=235050&highlight=

[jbear]

Thanks everybody for your replys.

As far as the 4:3 thing, I do understand ratios, but transfering inches (or centimeters) does not always translate to pixel count.

In all cases that I am aware of, the capture programs (when the intent is to produce an editable AVI) have a number of choices, like the two puzzling choices 720x480 or 640x480.

Which one would be the best choice for AVI (full screen) to be turned into a NTSC DVD?

There are also a couple of choices for NTSC ie: NTSC M, and NTSC 433?

All I really want is a setting to produce, in the end, a relatively accurate image on the DVD or on the television screen.

I did find out that Nero is not compatable with the Plextor Convertx PX-402U. Since Nero has stopped answering my emails I got this from Plextor. The AVI format from this device, and software written to support the device will also not produce a file that Nero will accept.

Frustrating, isn't it.

jbear

[jagabo]

In all cases that I am aware of, the capture programs (when the intent is to produce an editable AVI) have a number of choices, like the two puzzling choices 720x480 or 640x480.

Which one would be the best choice for AVI (full screen) to be turned into a NTSC DVD?

As I said earlier, 640x480 is to provide 4:3 for square pixel formats (like many AVI files), 720x480 is to provide 4:3 for DVD and DV. Use 640x480 if you are producing AVI or WMV files for the computer, 720x480 for use on DVD.