QuickTime 4 Reference

Data Handler Components

QuickTime 2.0 introduced a memory-based data handler. This data handler component works with movie data that is stored in memory (referenced by a handle) instead of in a file. This data handler has a component subtype value of



 
HandleDataHandlerSubType ('hndl')

To create a movie that uses the handle data handler, set the data reference type to HandleDataHandlerSubType when you call the NewTrackMedia function. Note that the movie data in memory is not automatically saved with the movie. If you want to save the data that is in memory, use the FlattenMovie or InsertTrackSegment functions to copy the data from memory to a file. Note that there is a special flag for FlattenMovie and data handlers. For more information, see "Flattening Flags" .

The handle data handler does not use aliases as its data reference, and therefore does not use alias handles. Rather, it uses 4-byte memory handles as its data reference. The data reference contains the actual handle that stores the needed data. If you pass a handle value of nil , the data handler allocates and manages the handle for you. If you pass a handle value other than nil , the data handler uses your handle. It is then your responsibility to manage the handle and dispose of it when appropriate. Note that a single handle may be shared by several data handler components. Whenever new data is added, the data handler resizes the handle to accommodate new data.

Although data handler components have existed since QuickTime 1.0, their interface was publicly defined for the first time in QuickTime 2.0. If you are interested in developing a data handler, refer to "Data Handler Components."