After Effects CS4 for Windows and Macintosh: Compositions
Without compositions, a project is nothing more than a list of footage items—a grocery list without a recipe, an ensemble without choreography, finely tuned instruments without a musical score. This is because compositions perform the essential function of describing how footage items are arranged in space and time. This chapter shows you how to create a composition and define its spatial and temporal boundaries by setting frame size, frame rate, duration, and so on.
This chapter also describes the fundamental process of layering footage in compositions—and in so doing, lays the groundwork for the rest of the book, which focuses largely on how to manipulate those layers. The footage items you add to a composition become layers, which are manipulated in the defined space and time of the composition, as represented by Composition and Timeline panels. The following pages give you an overview of these panels as well as the Preview panel.
This chapter also introduces you to the idea of nesting, using comps as layers in other comps—a concept you’ll appreciate more fully as your projects grow more complex.
Because compositions describe how layers are arranged in space and time, you must define a composition’s spatial attributes such as its frame size and pixel aspect ratio (PAR), as well as its temporal aspects such as its frame rate. Because frame size, PAR, and frame rate are defining characteristics of any output format, you might consider these comp settings to be fundamental. Other settings include the comp’s viewing resolution, starting timecode, and duration.
A project usually contains several compositions, some of which are contained as layers (or nested) in a comp destined for export—the final comp. Although you would set a final comp’s settings to match a particular output format (NTSC DV, for example), you might employ different settings (particularly for frame size and duration) for intermediate compositions.
When you create a comp, you must specify its attributes in a Composition Settings dialog, but you can change the settings whenever you want.
The Composition Settings dialog is divided into Basic and Advanced panels. With the exception of the comp anchor setting, the following sections focus on the basic settings, which are all you need to get started. Other advanced settings are addressed in later chapters, where they’ll make more sense to you. And rest assured, you’ll be reminded of the appropriate comp setting whenever a task or technique calls for it.