Understanding standard def., 720X480 vs. 640X480

[Vincent Rosati]

I realize this is a late response. Anyway, here is link to some info that I found useful in understanding video specs:
https://lipas.uwasa.fi/~f76998/video/

To my understanding, Standard definition like DV was created as a bridge between Analog and Digital.
Analog television was a D1 format, 720×486. DV is 720×480. The 6 missing vertical lines allow DV’s dimensions to be divisible by 16, which is the block size of common compression systems. And it removes top and bottom pixel rows, which are typically the most degraded lines in an analog signal.

640×480 is a square pixel frame size for Full Screen DV video.
I think DVD specifications allow for 640×480, it wouldn’t be pillarboxed on a standard full screen display, so long as the DVD is encoded properly, and the playback unit hasn’t had a user controlled setting that would interfere with it.

A lot of confusion comes from there being a lot of incomplete information out there, and many times number are rounded so you are not actually working with the correct numbers. You have to dig real deep to find the type of numbers you are looking for.

In DV, both Full Screen and Widescreen are 720×480.
Full Screen 4:3 has a Pixel Aspect Ratio of 0.9 (approximate!, It’s closer to 0.89), so 720×0.89=640 (rounded to the nearest integer divisible by 16). So, Full Screen 720×480, when displayed properly, appears as 640×480.
Widescreen 16:9 has a PAR of 1.2. So 720×1.2=864, which is the width that widescreen appears in when it is displayed properly.

It’s a jungle out there.

Vince

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[Sky Spooner]

Hi,

I stumbled on to your post because I have a related question. I’m encoding a program from DVD using stream clip so that I can deliver to the iTunes video store. The program is an 80s concert video that is 4×3 NTSC. However, Apple spec calls for 4×3 to have 720×480 resolution. But when I encode at 720×480 the program appears stretched. If I encode at 640×480 it looks correct. I know Apple will reject if I deliver 640×480.

What can I do to deliver as a 720×480 without it looking stretched? I have Final Cut at my disposal if need be.

Any ideas?

[Vincent Rosati]

Probably either…
Edit in a DV 720×480 Full Screen (0.9:1) project, this would fill the screen and display properly so long as the playback method honors the PAR flag.
Or pillarbox the 640×480 into a 720×480 square pixel (1:1) project.

If it’s a long program, it’s usually a good idea to do encoding tests before doing the final encode – just encode a 10-30 sec. clip to see if everything looks as you expect.

Vince

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[Rory Newman]

Hi chaps.

Want to encode a film in MPEG4 to give to the subjects for use with a portable DVD player (on a usb stick.)

Never used MPEG4 or a portable dvd player before. But one I looked at on the web said it accepted MPEG4 at SD. So I’m compressing my 1920×1080 Apple Pro Res 422 into MPEG4 custom 16:9 frame size 640×360 pixel aspect 1.

Is this right?

Basically, we’re gonna buy our subjects a portable DVD player so they can see themselves. (Burned a couple of SD disks too, but want to give them an unscratchable stick as well.)

Obviously would like it in the best quality, but needs to be played by the player.

Do you think this is the right frame size for MPEG4 SD? (Or would a player accept a 720 or even 1080 frame size if it’s MPEG4?)

Help much appreciated as my partner’s flying out today and will see them in a couple of days.

Thanks in advance.