In response to application requests, sequence grabber components can use channel components in two ways: to play digitized data for the user or to save captured data in a QuickTime movie. The process of playing digitized data is called previewing ; saving captured data in a movie is called recording . Applications can use previewing to allow the user to prepare to make a recording. Applications that use previewing can move directly from the preview operation to a record operation, without stopping the process.
The next two sections provide an overview of preview and record operations. A third section discusses the callback functions that are supported by some channel components.