Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 620

Note: (Mac OS only) If you intend to use key frames in the movie, hold down Option and adjust the Quality slider to
control the temporal compression of the movie. Temporal compression compresses a movie by comparing successive
frames and keeping only changed data. High temporal quality maintains smoothness of motion. Low temporal quality
tends to produce jerkiness of motion because a pixel doesn't change unless the difference between frames is great.
If you want the smallest possible files, and your compressor choice allows for a key frame rate, select the box and
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type a number in the Key Frame Every box. Generally, you should type a number equal to the frame rate. For
example, if you set a frame rate of 30 fps, type 30 in the Key Frame box. This sets one key frame every 30 frames of
your movie.
Note: If you are going to use the resulting movie in another After Effects composition, type a small value (less than 5) in
the Key Frame Every box or deselect the Key Frame Every option. The presence of key frames greatly increases the
memory required to edit and render a movie.
Click OK.
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If your compressor choice supports different image color depths, choose the appropriate color depth in the Output
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Module Settings dialog box:
• Choose Millions Of Colors+ if you want 24-bit color quality and you want your composition background to be
transparent (to include an alpha channel). The composition's background color is disregarded. Only Animation
and None can support the Millions Of Colors+ color depth.
• Choose Millions Of Colors if you want 24-bit color quality but want to include your composition background
color (no alpha channel).
Note: Color depth settings of Thousands Of Colors or lower may cause banding and dithered images.
Specify other settings in the Output Module Settings dialog box, and then click OK.
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See also
"Work in the Render Queue panel" on page 585
"Work with output module settings" on page 594
QuickTime compression options
Choices you make in the Compression Settings dialog box require tradeoffs between file size and movie quality. The
higher the visual quality of your movie, the larger the file size.
The Quality control specifies the spatial compression of the movie, which compresses the data in each frame
Quality
of a composition. Higher quality produces better image quality but results in a bigger movie file. Note that this
quality is unrelated to each layer's quality setting in After Effects.
In QuickTime terminology, the term key frames is different from the change-over-time keyframes
Key Frame Every
placed in the After Effects Timeline panel. In QuickTime, key frames are frames that occur at regular intervals in the
movie. During compression they are stored as complete frames. Each intermediate frame that separates them is
compared to the previous frame, and only changed data is stored. This greatly reduces movie size. Shorter intervals
between key frames enable faster seeking and reverse playback, but can significantly increase the size of the file.
Specify Video for Windows compression options
1 In the Render Queue panel, click the underlined name of the output module.
Choose Video For Windows from the Format menu.
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3 Click Format Options in the Video Output section.
AFTER EFFECTS CS3 614
User Guide