Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Sequence Grabber Component Functions / Working With Channel Characteristics

SGSetChannelUsage

The SGSetChannelUsage function specifies how a channel is to be used by the sequence grabber component. The sequence grabber component does not use a channel until you specify how it is to be used. You can specify that a channel is to be used for recording or previewing, or both. In addition, you can control whether the data captured by a channel is displayed during the record or preview operation.

pascal ComponentResult SGSetChannelUsage (SGChannel c, 
                                          long usage);

c

Specifies the reference that identifies the channel for this operation. You obtain this reference from the SGNewChannel function, described on page 5-29.

usage

Contains flags (defined by the SeqGrabUsageEnum data type) specifying how the channel is to be used. You may set more than one of these flags
to 1. Set unused flags to 0. The following flags are defined:

seqGrabRecord

Indicates that the channel is to be used during record operations. Set this flag to 1 to use a channel for recording.

seqGrabPreview

Indicates that the channel is to be used during preview operations. Set this flag to 1 to use a channel for previewing.

seqGrabPlayDuringRecord

Indicates that the sequence grabber may play the data captured by this channel during a record operation. If you set this flag to 1, the data from the channel may be played during the record operation, if the destination buffer is onscreen. Video data is displayed; sound data is played through the computer's speaker. However, playing the data may affect the quality of the recorded sequence by causing frames to be dropped. Set this flag to 0 to prevent the channel's data from being played during a record operation.

DESCRIPTION

You cannot call the SGSetChannelUsage function during a record or preview operation.

RESULT CODES

notEnoughMemoryToGrab	-9403	Insufficient memory for record operation
notEnoughDiskSpaceToGrab	-9404	Insufficient disk space for record operation
deviceCantMeetRequest	-9408	Device cannot support grabber

Main | Top of Section | What's New | Apple Computer, Inc. | Find It | Feedback | Help