Math question: what zoom % = standard def?

eveaudio wrote:

.... to end up on a standard def DVD. ...

any DVD-creation program, I know, does the scaling of HDef material automatically, so why doing computation manually, when a computer does better ... ? 😉

eveaudio wrote:

I am looking to zoom in to my subject to frame the picture better, but I don't want to zoom in so much that I am damaging the resolution of SD video.

why exactly does your profile say "Pro Audio & Video Productions"?

eveaudio wrote:

I think you may misunderstand my question: I am looking to zoom in to my subject to frame the picture better, but I don't want to zoom in so much that I am damaging the resolution of SD video.

When you import any 16:9 HDef into any DVD-authoring app, it will automatically do the math.

When you 'zoom' in FC your picture, the final result is a tiny stamp of your video with a huge black border, top/bottom, l/r on DVD... why do you want that?

HD resolution is 1920 x 1080 pixels (16:9 format) with square pixels. NTSC SD is 720 x 480 (4:3 format). To achieve 16:9 format with SD the pixels are stretched so they are not square but have a 40:33 width to height aspect ratio. This yields an "effective" 872 x 480 square pixel resolution. While there is not an exact "zoom" level to achieve what you want, I think 220% will get you close (1920/872 x 100). Give it a try!

Karsten,

I think you really misunderstood ... what the OP is trying to understand is how far he/she can zoom INTO the HD frame before messing with picture quality.

At least I think that's what it is ... it took me a while to figure out.

mish

Further to my previous reply - assuming you are editing HD to start with, zooming in will cause a loss in resolution and then when you make a standard def DVD you will have a further loss in resolution so that the final result may be unsatisfactory - that's why you should give it a try.

mishmumken wrote:

.... how far he/she can zoom INTO the HD frame before messing with picture quality.

At least I think that's what it is ... it took me a while to figure out.

ahhhhh < slapping own forhead > gottit!!

hmmm.... 1920 is FullHD, a DVD is 720 ... which is 37.5% of 1920 ... or a Zoom of x2.666 ...

Karsten Schlüter wrote:

ahhhhh < slapping own forhead > gottit!!

hmmm.... 1920 is FullHD, a DVD is 720 ... which is 37.5% of 1920 ... or a Zoom of x2.666 ...

.... if it's not 1440 x 1080 ... or maybe it's 1280x720 ... who knows?

mish

Hi Eveaudio:

If I follow your original question correctly, it sounds like all you're looking to do is crop the image from a HD frame size to a SD frame size. The end result when viewed as SD source will have a zoom in when compared to the original HD picture.

You'll need a Sequence at the SD settings you want to be using. Then, drag and drop your HD source clip into it. If using FCP7, it will ask you if you want to change the Sequence settings to match the clip, choose "No".

Most likely, Final Cut Pro will scale the HD source to fit the SD Sequence. Double-click on the HD clip in the Sequence to open it in the Viewer window, click the Motion tab, and set the scale back to 100. You can also reposition the shot if needed/wanted. Depending on the SD Sequence settings you might notice a change to the Aspect Ratio value under the Distort options. That may be the tricky part in what you're doing depending on your HD footage and your SD Sequence if either or both use non-saquare pixels. You'll also have to keep an eye on what's happening with your Field Dominance. Depending on your source and your Sequence (as well as your intended output), you may need to remove, shift or reverse the fields (depending on which version of FCP that you're using, it may do this for you automatically by applying a Filter).

-Warren