Determining Video Height from Width & Aspect Ratio

[d4jaj1]

Hello,

I have standard 720 x 480 NTSC AVI video in 16:9 aspect ratio. I want to convert the video into FLV format for use on the web. I have all of the software I need to do the conversion, what I'm a little stuck with is the proper height in pixels.

The website I'm designing, the width needs to be 512px (which is divisible by 16). So, what is the formula I should use to determine the correct height - while maintaining 16:9 aspect ratio and avoiding distortions? I assume the height needs to be divisible by 16 as well - correct?

Thanks.

[zoobie]

Divide it by 1.78 and get 287.64 rounded to 288px which is divisible by 16

[manono]

(512 x 9)/16 = 288

Pretty much what zoobie said.

[d4jaj1]

Thanks. One question that always bugged be though. I ave two consumer cameras - one shoots in 16:19 and the other 4:3 - but both produce 720x480 video (obviously with different aspect ratios).

My confusion is - shouldn't the 16:9 version have different dimensions - since it's wider & shorter - say 688 x 382??? If not, why. As you can see, I'm struggling with separating aspect from pixel size.

[manono]

My confusion is - shouldn't the 16:9 version have different dimensions?

No, they'll both be 720x480. The DAR (Display Aspect Ratio - either 4:3 or 16:9) says how they'll be resized at playback time so things look 'normal'. Even 720x480 isn't a 4:3 ratio. It's 1.5:1 or 3:2, and also gets resized.

[jagabo]

DAR = PAR * SAR

DAR = display aspect ratio, the final shape of the picture
PAR = pixel aspect ratio, the shape of individual pixels
SAR = storate aspect ratio, the frame size

For example:

DAR = PAR * SAR
4:3 = 10:11 * 704x480
4/3 = 10/11 * 704/480
1.333 = 1.333