Configuration Functions for All Channel Components
Sequence grabber components use channel components to obtain digitized data from external media. Your channel is assigned to a sequence grabber component when the application calls the sequence grabber component'sSGNewChannelfunction, described in the chapter "Sequence Grabber Components" in this book. The sequence grabber component must configure your channel before a preview or record operation. Your channel component must provide a number of functions that allow the sequence grabber to configure the characteristics of your channel. Several of these functions work on any channel component. This section discusses these general channel configuration functions.In addition, channel components provide functions that are specific to the channel type. The sequence grabber component supplied by Apple uses two types of channel components: video channel components and sound channel components. See "Configuration Functions for Video Channel Components," which begins on page 6-59, for information about the configuration functions that work only with video channels. See "Configuration Functions for Sound Channel Components," which begins on page 6-74, for information about the configuration functions that work only with sound channels.
The
SGSetChannelUsagefunction specifies how your channel is to be used. The sequence grabber component can restrict a channel to use during record or preview operations. In addition, this function allows the sequence grabber component to specify whether your channel plays during a record operation. TheSGGetChannelUsagefunction allows the sequence grabber component to determine a channel's usage.The
SGGetChannelInfofunction allows the sequence grabber component to determine some of the characteristics of your channel. For example, this function returns information indicating whether your channel has a visual or an audio representation.The
SGSetChannelPlayFlagsfunction lets the sequence grabber component influence the speed and quality with which your channel plays captured data. TheSGGetChannelPlayFlagsfunction allows the sequence grabber component to determine these flag settings.The
SGSetChannelMaxFramesfunction establishes a limit on the number of frames that your channel component will capture from a channel.The
SGGetChannelMaxFramesfunction enables the sequence grabber component to determine that limit.The
SGSetChannelRefConfunction allows the sequence grabber component to set the value of a reference constant that your component passes to its callback functions (see "Using Callback Functions for Video Channel Components," which begins on page 6-33, for information about the callback functions that are supported by video channels).The
SGGetDataRatefunction allows the sequence grabber component to determine how many bytes of captured data your channel is collecting each second.The
SGGetChannelSampleDescriptionfunction allows the sequence grabber to retrieve your channel's sample description. TheSGGetChannelTimeScalefunction allows it to obtain your channel's time scale.The sequence grabber can modify or retrieve your channel's clipping region by calling the
SGSetChannelCliporSGGetChannelClipfunction, respectively. The sequence grabber can work with your channel's transformation matrix by calling theSGSetChannelMatrixandSGGetChannelMatrixfunctions.
Subtopics
- SGSetChannelUsage
- SGGetChannelUsage
- SGGetChannelInfo
- SGSetChannelPlayFlags
- SGGetChannelPlayFlags
- SGSetChannelMaxFrames
- SGGetChannelMaxFrames
- SGSetChannelRefCon
- SGGetDataRate
- SGGetChannelSampleDescription
- SGGetChannelTimeScale
- SGSetChannelClip
- SGGetChannelClip
- SGSetChannelMatrix
- SGGetChannelMatrix
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