User Manual
Chapter 5 Custom settings and output formats 92
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Aspect Ratio: Choose the aspect ratio of your video le. The default is 4:3. The other option
of 16:9 is used for anamorphic DVD. The aspect ratio determines how the picture lls the
television screen. A 16:9 (widescreen) DVD viewed on a typical 4:3 television appears in
letterbox format (black bars at the top and bottom of the screen). However, a widescreen DVD
displayed on a 16:9 (widescreen) TV lls the screen.
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Field Dominance: Choose whether the top eld or the bottom eld of your interlaced source
media le will be the dominant (rst) eld in the output MPEG-2 video le. If you choose
Automatic (the default), Compressor analyzes the source video and attempts to determine
eld dominance automatically. The bottom eld is dominant for DV source video. This setting
does not pertain to the 720p video format, because that format must be progressive.
Note: For interlaced video, the top eld is also known as the upper or odd eld, and the
bottom eld is also known as the lower or even eld.
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Choose start timecode: If you leave the checkbox unselected (the default), Compressor embeds
the source media le’s existing timecode in the output media le. Selecting this checkbox
allows you to override the source media le’s timecode and enter a new timecode value in the
timecode eld. This eld is dimmed unless the checkbox is selected, and if it’s left blank, the
output media le uses the default starting timecode value of 00:00:00:00.
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Drop Frame: If you select the “Choose start timecode” checkbox, and you want your timecode
to be drop frame (rather than non-drop frame), you must also select this checkbox.
Timecode is a numbering system for labeling the frames in a video sequence. The type of
timecode designed for 30 fps video has a frame counter that counts from 0 to 29 and then
increments the seconds counter and returns to 0. This type of timecode, also known as non-
drop frame timecode, maintains an accurate measure of elapsed time for true 30 fps video.
However, the NTSC frame rate is 29.97 fps, so drop frame timecode was dened to provide
a more accurate measure of elapsed time for NTSC. Drop frame timecode skips frame
numbers 0 and 1 once a minute on the minute, except for every 10 minutes. For example,
drop frame timecode 01:08:59;29 is followed by 01:09:00;02, skipping timecode numbers
01:09:00;00 and 01:09:00;01.
Note: Drop frame timecode applies only if you’re using interlaced NTSC video.