Apple Final Cut Pro 7 - Manual (Page 1951)

Unlike output to standard definition tape, which may require letterboxing to fit in a 4:3
aspect ratio, there is no need to letterbox media files because they can have any
dimensions you want (in this case, 16:9).
Calculating the Dimensions for an Exported 16:9 QuickTime Movie
The dimensions of your exported movie depend on several factors, including any file size
limitations and height or width constraints. For example, if you are producing a website
in which every movie has a width of 320 pixels, regardless of height, then the width will
determine the height. To calculate the dimensions of your movie, use the following
formula, where aspect ratio is always 16:9:
aspect ratio = pixel width/pixel height
For example, if you want the width of your movie to be 320 pixels, the formula for pixel
height looks like this:
16/9 = 320/pixel height
Or, rewritten:
pixel height = 320/1.7777
In this case, your final movie dimensions should be 320 x 180 pixels.
Exporting a 16:9 QuickTime Movie for the Web
You can export your 16:9 anamorphic sequence to a native 16:9 movie using the Export
Using QuickTime Conversion command.
To export a 16:9 anamorphic sequence to a native 16:9 QuickTime movie
1 In the Browser, select the 16:9 anamorphic sequence you want to export.
2 Choose File > Export > Using QuickTime Conversion.
3 Choose QuickTime from the Format pop-up menu, then click Options.
4 In the Movie Settings window, click Settings.
5 Choose a popular online codec from the Compression Type pop-up menu, select options
for the codec, then click OK.
For example, choose Sorenson Video 3 or MPEG-4 Video.
6 In the Movie Settings window, click Size.
7 In the Export Size Settings window, choose Custom from the Dimensions pop-up menu.
8 In the Dimensions width and height fields, enter the width and height you calculated for
your exported 16:9 movie.
For more information, see “Calculating the Dimensions for an Exported 16:9 QuickTime
Movie.”
1951 Appendix E Working with Anamorphic 16:9 Media