SWF files are small files that play in Flash
Player. They are often used to deliver animated vector graphics
(such as cartoons), audio, and other data types over the Internet.
SWF files also allow viewer interaction, such as clicking to follow
a web link, control animation, or provide input to a rich internet
application (RIA). SWF files are the output created from FLA files.
rendering and exporting a movie to a SWF file, After Effects maintains vector
graphics as vector objects as much as possible. However, raster
images, blending modes, motion blur, some effects, and the contents
of nested compositions cannot be represented as vectors in the SWF
file and are rasterized.
You can choose to ignore these unsupported
items so that the SWF file includes only the After Effects features
that can be converted into native SWF elements, or you can choose
to rasterize frames that contain unsupported features and add them
to the SWF file as JPEG-compressed bitmap images, which may reduce
the efficiency of the SWF file.
Audio is encoded in MP3 format
and added to the SWF file as an audio stream.
When After Effects
creates a SWF file, it also saves a report ([SWFfile_name]R.htm) to
the same folder as the SWF file. The report also contains a link
to the SWF file so that you can preview the output using the Flash
Player plug-in. Open the report in a browser to view the SWF file
and see which items in the composition are unsupported.
exported SWF file includes each unchanged item in the After Effects
composition once, and then references it for each use. If a layer
is used in multiple frames, each use refers to the same object,
even if the layer’s transform properties (such as Position) are
animated. However, if the content of the layer changes—for example,
if a mask on the layer is animated or if the source footage item
for the layer is video—a new object is created for each frame in
which the layer is visible. If multiple layers in the composition
share the same source footage item, the source is added once and
is then referenced for every additional layer that shares the source.
If the source is an Illustrator file, a SWF movie clip is created
and referenced. Text characters are added as vectors once and then
referenced on all subsequent frames, unless you choose Fill Over
Stroke from the Fill And Stroke options menu; in that case, the
characters are added as vectors on every frame.