Road Map to QuickTime 3

Media Handlers: Creating Media Handler Components

Media handler components (also called media handlers, or just handlers) allow the Movie Toolbox to manipulate the data in a media. These media handlers isolate the Movie Toolbox (and the applications programmer) from the details of how and where a media is stored. They are also called "derived" media handlers, because they are derived from a base media handler, provided by Apple.

The base media handler component handles most of the duties that are common to all media handlers, freeing the component developer to focus on the task of reading and writing a particular media type.

In general, only developers who are creating a new media handler need to read this chapter. Applications do not normally interact with media handlers directly; applications make calls to the Movie Toolbox, which calls media handlers as needed. Applications programmers may want to read the section "About Derived Media Handler Components," to gain a better understanding of QuickTime architecture.

In addition, there are two functions of derived media handlers that applications may call directly: MediaGetGraphicsMode and MediaSetGraphicsMode . Interested programmers should refer to the definitions of these functions.

About Derived Media Handler Components

Inside Macintosh describes what media handler components are, and how they are used. It also explains the difference between media handler components and derived media handler components.

• Media Handler Components
• Derived Media Handler Components

Creating a Derived Media Handler Component

Inside Macintosh describes the process of creating a derived media handler component. The component and request flags are defined, and a listing of a sample component is provided.

• Component Flags for Derived Media Handlers
• Request Processing
• A Sample Derived Media Handler Component
•    Implementing the Required Component Functions
•    Initializing a Derived Media Handler Component
•    Drawing the Media Sample

Functions

Inside Macintosh defines the functions you must support if you are creating a derived media handler, as well as functions which you may optionally support, and utility functions available to your component from the base media handler. QuickTime 3 Reference adds several new functions, and documents minor changes to existing functions.

New:

• General Data Management
• MediaGSetActiveSegment
• MediaInvalidateRegion
• MediaGetNextStepTime
• MediaTrackReferencesChanged
• MediaTrackPropertyAtomChanged
• MediaSetTrackInputMapReference
• MediaGetSampleDataPointer
• MediaReleaseSampleDataPointer
• MediaCompare
• MediaSetVideoParam
• MediaGetVideoParam
• MediaSetNonPrimarySourceData
• MediaGetOffscreenBufferSize
• MediaSetHints
• MediaGetName
• Graphics Data Management
• MediaGetDrawingRgn
• MediaGetGraphicsMode
• MediaSetGraphicsMode
• Sound Data Management
• MediaSetSoundLocalizationData
• Management of Progressive Downloads
• MediaMakeMediaTimeTable

Changed:

• MediaIdle
• MediaIdle(changes)

Original:

• Managing Your Media Handler Component
• MediaInitialize
• MediaGGetStatus
• General Data Management
• MediaPutMediaInfo
• MediaGetMediaInfo
• MediaSetActive
• MediaPreroll
• MediaSetRate
• MediaTrackEdited
• MediaSampleDescriptionChanged
• MediaHasCharacteristic
• MediaSetMediaTimeScale
• MediaSetMovieTimeScale
• Graphics Data Management
• MediaSetGWorld
• MediaSetDimensions
• MediaSetMatrix
• MediaSetClip
• MediaGetTrackOpaque
• MediaGetNextBoundsChange
• MediaGetSrcRgn
• Sound Data Management
• MediaGSetVolume
• Base Media Handler Utility Function
• MediaSetHandlerCapabilities

Data Type

Inside Macintosh defines the GetMovieCompleteParams data type, used by the MediaInitialize function. QuickTime 3 Reference documents a new parameter for this structure, and a change in the version parameter.

Constants

Inside Macintosh defines the constants used to communicate with derived media handler components. QuickTime 3 Reference defines several new constants, which allow you to select the video parameters you wish to adjust.