Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Application-Defined Functions /

MyAddFrameFunction

The sequence grabber component calls your add-frame function in order to add a frame to a movie. Your add-frame function must support the following interface:

pascal ComponentResult MyAddFrameFunction (SGChannel c, 
                                          short bufferNum,
                                          TimeValue atTime, 
                                          TimeScale scale,
                                          SGCompressInfo *ci, 
                                          long refCon);

c

Specifies the reference that identifies the channel for this operation.

bufferNum

Identifies the buffer for this operation. You can obtain information about this buffer by calling the SGGetBufferInfo function, which is described on page 5-98.

atTime

Specifies the time at which the frame was captured, in the time scale specified by the scale parameter. Your add-frame function can change this value before adding the frame to the movie or before calling the SGAddFrame function, which is described on page 5-103. You can determine the duration of a frame by subtracting its capture time from the capture time of the next frame in the sequence.

scale

Specifies the time scale of the movie. You must not change this value.

ci

Contains a pointer to a compression information structure (defined by the SGCompressInfo data type). This structure contains information describing the compression characteristics of the image to be added to the movie. See "The Compression Information Structure" beginning on page 5-20 for a description of this structure.

refCon

Contains a reference constant value. You can set this value by calling the SGSetChannelRefCon function, which is described on page 5-64.

DESCRIPTION

You can use your add-frame function to modify the contents of the frame before it is added to the movie. This can be useful if you want to place frame numbers onto frames you are recording.

RESULT CODES

cantDoThatInCurrentMode

-9402

Request invalid in current mode

Memory Manager errors

SEE ALSO

Your add-frame function can use the sequence grabber component's SGAddFrame function to support the default behavior. SGAddFrame is described on page 5-103.

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