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.
- Quality
-
The Quality control specifies the spatial compression of
the movie, which compresses the data in each frame 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.
- Key Frame Every
-
In QuickTime terminology, the term key frames is
different from the change-over-time keyframes 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.