Creating an Effect Description

An effect description tells QuickTime which effect to execute and contains the parameters that control how the effect behaves at runtime. You create an effect description by creating an atom container, inserting a QT atom that specifies the effect, and inserting a set of QT atoms that set its parameters.

There are support functions you can call to assist you in this process. QTCreateStandardParameterDialog returns a complete effect description that you can use, including user-selected settings; you only need to add kEffectSourceName atoms to the description for effects that require sources. At a lower level, QTGetEffectsList returns a list of the available effects and ImageCodecGetParameterList will return a description of the parameters for an effect, including the default value for each parameter in the form of a QT atom that can be inserted directly into an effect description.

Structure of an Effect Description

Required Atoms of an Effects Description

Parameter Atoms of an Effects Description

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© 1999 Apple Computer, Inc.

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