Adobe After Effects CS4 - Manual (Page 715)

709 USING AFTER EFFECTS CS4
Rendering and exporting
Last updated 12/21/2009
Limitations of exporting a composition to XFL format
When Flash Professional opens an XFL file, it must load all of the assets into memory. After Effects warns you when
you export a composition for which the assets will consume more than 580 MB. Similarly, After Effects warns you if
the amount of time that an XFL file will take to open in Flash Professional is very large because the number of frames
in a PNG sequence is greater than 1,050. You can still export a composition to XFL format if it exceeds these limits,
but you may not be able to open the XFL file with Flash Professional.
To prevent the long load times related to sequences with a large number of PNG files, consider pre-rendering layers
based on PNG sequences to FLV format.
After Effects relies on the embedded version of the Adobe Media Encoder to create FLV files. The Adobe Media
Encoder can’t create FLV files with pixel dimensions greater than 1920x1080.
When you export a composition to the XFL format from a 32-bpc project, the rendering of colors with values under 0
and over 1 does not produce results that preserve the appearance of the composition in After Effects. You should only
work in an 8-bpc or 16-bpc project when creating a composition that you intend to export to Flash Professional in XFL
format.
Audio is not exported to the XFL file.
Render and export a composition as a SWF file
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.
While 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.
The 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.