Overview

This chapter introduces you to QuickTime video effects. You can use real-time video effects for a number of purposes. You can use transition effects to control the visual transition between two sources. Sources can be tracks in a QuickTime movie, or they can be graphics worlds. You can use filter effects to visually alter a single source, such as applying a blur or ripple. You can also use free-standing effects, such as a cloud or fire effect, that do not require a source (though they can be composited with other video).

QuickTime includes over a hundred different effects, and QuickTime's extensible architecture allows you to create additional effects of your own.

Because QuickTime effects are calculated and executed at runtime, they typically result in a much smaller file than a pre-rendered version of the same visual effect. In addition, QuickTime effects can be applied even if the appearance of a QuickTime movie at a given time is not known in advance. This means, for example, that you can include effects in a movie that contains sprites, which can change a movie's appearance as a result of user interactions.

Effects tracks can be created, edited, and used in essentially the same manner as other video tracks. You can "stack" effects by using one effects track as the source for another effect.

You need to read this chapter if you are writing an application that creates QuickTime movies and you want to add video effects to those movies. This is explained in the section "Adding Video Effects to a QuickTime Movie" .

You can also use an effect as the source for a sprite track, making the fire effect into a sprite, for example. Create the effect description and sample description, as described in the section "Adding Video Effects to a QuickTime Movie" , then add the effect description as a sprite media sample just as you would add a normal video sample.

In creating QuickTime movies with video effects, you will want to provide the user with ways to choose which effects to apply, when to apply them, and how to customize the effects chosen. These topics are discussed in the section "Video Effects User Interface" .

You should also read this chapter if you want to use video effects on graphics worlds without creating a QuickTime movie. You will need to read the section "Using Video Effects Outside a QuickTime Movie" , as well as the section "Adding Video Effects to a QuickTime Movie" , which discusses the structure of an effect.

If you want to create new video effects of your own, you need to read the section "Creating New Video Effects" .

This chapter also contains two reference sections:

• "Built-in QuickTime Video Effects" describes the set of video effects built into QuickTime 3, including implementations of the standard effects defined by the Society of Motion Picture and Television Engineers (SMPTE), as well as set of useful extra effects implemented by Apple Computer, Inc.
• "QuickTime Video Effects Reference" describes the constants, data types, and functions related to QuickTime video effects.