Apple Final Cut Pro 7 - Manual (Page 1771)

Important: These options do not take into account the effect of pixel aspect ratio when
determining what aspect ratio to preserve. For example, if you are exporting a DVCPRO
HD sequence (960 x 720), these options preserve the aspect ratio of the pixel dimensions,
which is 4:3 (960720), not 16:9 as you would expect. For best results, always nest
sequences with nonsquare pixels into a sequence format with square pixels. In this
case, you could nest your DVCPRO HD sequence into a sequence with dimensions of
1280 x 720.
1280 x 720 (16:9)
sequence
• Letterbox: Scales your clip or sequence video to fit proportionally in the clean aperture
dimensions of your exported movie. Black bars are added on the top and bottom
(letterboxed) or left and right (pillarboxed) as necessary.
16:9 letterboxed within
320 x 240 (4:3)
• Crop: Scales and center-crops your clip or sequence video to fit in the clean aperture
dimensions of your exported movie.
16:9 cropped
to 320 x 240 (4:3)
1771 Chapter 106 Exporting Using QuickTime Conversion