Datasheet

■ Setting Up a Composite 21
alpha channel, change the menu to RGB+Alpha. You can also choose to render straight or
premultiplied alpha through the Color menu. (For information on alpha and premultiplica-
tion, see Chapter 3). Finally, the Output Module Settings dialog box offers a means to res-
cale or crop an output through the Stretch and Crop check boxes. Note that the dialog box
carries a Color Management tab, which allows you to render a composite to a specific color
space. This process is discussed in Chapter 2.
The Log section sets the style of an
error log text file that’s written to disk.
Output To sets the name and location
of file(s) to be written. To select a name
and location, click the current filename
(for example,
Comp1.avi). The Output
Movie To dialog box opens. Enter the
name into the file name cell using the
format
name.[#].extension for an
image sequence and
name.extension
for QuickTime or AVI movies. For
example,
test.[##].tga is suitable for
a Targa image sequence with 10 to 99
frames because it includes two numeric
placeholders.
Once the various render settings
are selected, you can launch the render by clicking the Render button at the top right of the
Render Queue tab. When the render finishes, the queued item remains listed. If you queue
an additional composition, it’s added to the queue list. You can delete an old queue by
selecting the item name in the list and pressing the Delete key.
Interlacing in AE
If you import interlaced video footage, the interlacing is recognized and is indicated by the
footage statistics provided at the top of the Project panel. The word separating is included
with an indication of which field is dominant (upper or lower, see Figure 1.19). An upper
field contains the odd lines of a frame, while the lower field contains the even lines of a
frame. Different video formats carry different field dominances, which affect the way edits
are made and how de-interlacing is carried out. When After Effects identifies interlacing,
it separates the fields and converts them to individual frames. In essence, this doubles the
frame rate. If you open the footage in the Footage panel, you can examine each separated
field by stepping through the Footage panel timeline with the Page Down and Page Up keys.
For example, if the footage has lower dominance and the timeline is at frame 1, the lower
field of frame 1 is displayed. Pressing the Page Down key once
displays the upper field of frame 1. Pressing the Page Down key a
second time displays the lower field of frame 2. The frame num-
ber is indicated by the Footage panel’s Current Time button.
If footage is field-separated and dropped into a composi-
tion, only the dominant field of each frame is displayed by the
Composition panel as you play the timeline (see Figure 1.20).
Both fields continue to exist and are used if the composition is
rendered with interlacing. You can force interlacing on the render
by changing the Field Render menu in the Render Settings dialog
Figure 1.18 The top of the Output Module Settings dialog box
Figure 1.19 Interlaced footage identified by
the word Separating in the Project panel
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