General Data Management(IM: QC)

Inside Macintosh: QuickTime Components /

Chapter 10 - Derived Media Handler Components / Derived Media Handler Components Reference

General Data Management
While the base media handler isolates your component from the details of media data access, your derived media handler still needs to keep track of certain information in order to support movie playback and creation. This section discusses functions that help your media handler manage its information.
Your media handler may store proprietary information in its media. The Movie Toolbox calls two media handler functions in order to give you an opportunity to retrieve or store this information. The MediaPutMediaInfo function allows you to store your special information in your media. The MediaGetMediaInfo function delivers that data to your media handler.
The Movie Toolbox tells your media handler when its track has been enabled or disabled by calling your MediaSetActive function. The Movie Toolbox prepares your handler for playback by calling your MediaPreroll function. Whenever your media's playback rate changes, the Movie Toolbox calls your MediaSetRate function. Whenever the track that uses your media is edited, the Movie Toolbox calls your MediaTrackEdited function.
If the Movie Toolbox has called its SetMediaSampleDescription function on a sample description, it uses the MediaSampleDescriptionChanged function to notify your media handler of the change.
The Movie Toolbox allows tracks to be identified by various characteristics. For instance, it is possible to request that all tracks containing audio information be searched. To determine whether a track has a given characteristic, the Movie Toolbox queries the media handler for each track. The Movie Toolbox calls the MediaHasCharacteristic function with the specified characteristic.
The Movie Toolbox uses two functions to inform you about changes to your media's time environment. The MediaSetMediaTimeScale function allows the Movie Toolbox to change your media's time scale. The MediaSetMovieTimeScale function allows the Movie Toolbox to tell you when the movie's time scale has changed.

Subtopics

MediaPutMediaInfo

MediaGetMediaInfo

MediaSetActive

MediaPreroll

MediaSetRate

MediaTrackEdited

MediaSampleDescriptionChanged

MediaHasCharacteristic

MediaSetMediaTimeScale

MediaSetMovieTimeScale