DV formatting and Pixel Aspect Ratios

[Gerry]

I'm trying to arrive at the correct screen size and Pixel Aspect ratio as I plan out my music video. Apparently the wide-screen HD images we've all become accustomed to (like the size, or rather the proportion, we did the Bus Stop jam) is not compatible with dvd formatting. I had planned out my whole project with the same wide-screen proportion as the Bus Stop jam but now I'm running into limitations in Adobe Encore, which I'd been planning on using for the authoring.

 

I was reading the thread on the Bus Stop forum where Darkwing and Robcat were going back and forth on various formats, and I just got confused. And Adobe Encore tells me that there's only one acceptable format for dvd, and all the others are apparently reserved for BluRay. So true wide screen is out, and I'm limited to 720 x 480 for the video.

 

Is this correct? I'm just trying to arrive at the correct format before I commit to any more designing and storyboarding, but the more I research it the more confused I get. I just want to create a dvd that will play on tv sets.

[Meowx]

Yes, standard DVDs are limited to 480p/i (720x480).

 

Blu-rays (and HD DVDs, but I think those are dead) can do 720p and 1080p/i (1280x720 and 1920x1080, respectively).

[robcat2075]

It is true that an NTSC DVD can only store 720x480 images.

 

However, there are two ways that DVD players show that. One way is to squeeze the 720 slightly so that it fits into an old-style 4:3 rectangle. The other is to stretch it slightly so it fills a 16:9 rectangle.

 

Most DVD software has a switch that tells the DVD to tell the DVD player how to interpret the 720x480 data stored on the DVD

 

Example from "DVD Styler"

 

 

(Note the term "aspect ratio". This is a different usage than pixel "aspect" in A:M.)

 

 

You're problem is to get your footage so that it looks right after it has been squished or squeezed.

 

One way is to render your image with square pixels and let the DVD software do the squishing when it re-compresses the video.

 

You would render "square pixels" (A:M aspect ratio 1) at 640x480 for a target of 4:3 and 854x480 for a target of 16:9

 

If your DVD software won't handle that then you need to render something other than square pixels.

 

Set your camera IN THE CHOR to render 720x480 pixels with an "aspect" of 1.18 if you want to make footage for 16:9 use. The camera in your A:M chor will display a frame that appear 16:9 even though it will render not 854x480, but 720x480

 

Use the camera settings when you render.

 

for 4:3 footage set your camera to render 720x480 pixels with an "aspect" of 0.88

A:M will display a camera frame that is 4:3 even though it will render not 640x480, but 720x480

 

 

 

This squishing and stretching is why NTSC DVDs can store widescreen movies and show them full screen on a 16:9 TV

 

OR

 

properly shrink everything down so they will be properly letterboxed on a 4:3 display.

[largento]

Gerry, here's the source I've been using for aspect ratio and pixel size info.

 

Standard NTSC DV is 720x480 at .91 aspect ratio

 

Widescreen NTSC DV is 720x480 at 1.21 aspect ratio

 

Note: for broadcast (D1) video the size is 720x486, but the aspect ratios are the same.

[Gerry]

Thanks folks, that's a help.

[zandoriastudios]

Great tip about changing the aspect ratio in the camera properties!