Apple Compressor (4.0) - Manual (Page 172)

Chapter 7 Advanced functions 172
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Percent of source: Modifies the output clip’s speed by a percentage of the source clip’s
speed. Type a custom percentage value in the field, or choose a preset value from the
adjacent pop-up menu (with a downward arrow). These preset values are intended for use
in specific situations:
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24 @ 25: Use this setting when you have 24 fps video that you want to convert to 25 fps for
PAL distribution.
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23.98 @ 24: Use this setting when you have 23.98 fps video and want to convert it to 24 fps.
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23.98 @ 25: Use this setting when you have 23.98 fps video and want to convert it to 25 fps
for PAL distribution.
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30 @ 29.97: Use this setting when you have 30 fps video and want to convert it to 29.97 fps.
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29.97 @ 30: Use this setting when you have 29.97 fps video and want to convert it to 30 fps.
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24 @ 23.98: Use this setting when you have 24 fps video and want to convert it to 23.98 fps
for NTSC DVD distribution.
With each of these settings, no intermediate video frames are required—the existing
frames are just set to play back faster or slower.
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Total duration: Sets a duration for the clip. As you change the duration (by modifying the
value slider), the percentage changes accordingly in the field above. This option is most
useful when you have a source media file whose duration is a bit longer or shorter than it
needs to be, and you’d rather change its playback speed than add or remove video frames.
With this method, intermediate video frames are created as needed.
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So source frames play at [frame rate] fps: Use this option when the source media file’s frame
rate does not match the Encoder pane frame rate (shown as the frame rate for this item).
About deinterlacing
You can use the frame controls in Compressor to deinterlace your video media.
NTSC and PAL video is interlaced. This means that each frame of video consists of two fields (1/60 of
a second apart), one with the odd broadcast lines of the image and one with the even broadcast
lines of the image. The differences between these two fields create the impression of motion:
The eye combines these two images into the optical illusion of a whole frame of smooth, realistic
motion at 30 fps in standard-definition (SD) television; and because of the high field-refresh speeds
(1/60 of a second) of broadcast television, the interlacing is virtually invisible to a casual viewer.