Required atoms of an effects description

Overview

There are several required atoms that an effect description must contain. The first is the kParameterWhatName atom. The kParameterWhatName atom contains the name of the effect. This specifies which of the available effects to use.

The code snippet shown in the following listing adds a kParameterWhatName atom to the atom container effectDescription. The constant kCrossFadeTransitionType contains the name of the cross-fade effect.

effectCode = kCrossFadeTransitionType;
QTInsertChild(effectDescription, kParentAtomIsContainer,
                kParameterWhatName, kParameterWhatID, 0,
                sizeof(effectCode), &effectCode, nil);

In addition to the kParameterWhatName atom, the effect description for an effect that uses sources must contain one or more kEffectSourceName atoms. Each of these atoms contains the name of one of the effect’s sources. An input map is used to map these names to the actual tracks of the movie that are the sources. Creating an input map describes how to create the input map.

See Also

Effect descriptions

• Structure of an effect description
• Parameter atoms of an effects description
• Creating an input map