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Inside Macintosh: QuickTime Components

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Recording

During a record operation, a sequence grabber component collects the data it captures and formats that data into a QuickTime movie. During a record operation, the sequence grabber component can also play the captured data for the user.

The following paragraphs discuss the steps the sequence grabber component follows to record captured data.

1. As with a preview operation, the sequence grabber component establishes a connection to your channel component by calling the Component Manager's OpenComponent function. It then initializes your component by calling your SGInitChannel function (described on SGInitChannel ).
2. The sequence grabber component then configures your component for the record operation. The SGSetGWorld function (described on SGSetGWorld ) sets the graphics world in which the data is to be displayed. The SGSetChannelUsage function (described on SGSetChannelUsage ) specifies each channel that is to be used for recording. At this time, the sequence grabber component can also specify whether your component is to play its data while recording. The application can then use the appropriate channel configuration functions to prepare your channel for the record operation. For video channels, it uses the functions discussed in "Configuration Functions for Video Channel Components," . For sound channels, the sequence grabber uses the functions discussed in "Configuration Functions for Sound Channel Components," .
3. The sequence grabber component starts the record operation by calling your SGStartRecord function (described on SGStartRecord ). The sequence grabber component then begins collecting data from the channels it has assigned, stores the data in a QuickTime movie, and, optionally, plays that data appropriately. The sequence grabber can pause and restart the record process by calling the SGPause function (described on SGPause ). During the record operation, the sequence grabber component calls your SGIdle function (described on SGIdle ) frequently, so that your channel can perform its operation. The sequence grabber component uses the SGStop function (described on SGStop ) to stop the record operation. At this time, your component saves the movie in the appropriate movie file if the sequence grabber component instructs your component to do so by calling your SGWriteSamples function (described on SGWriteSamples ).
4. When the application is done recording, it either returns to previewing or closes its connection to your component.

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