Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Sequence Grabber Component Functions / Utility Functions for Video Channel Callback Functions

SGGetBufferInfo

You can use the SGGetBufferInfo function to obtain information about a buffer that has been passed to your callback function.

pascal ComponentResult SGGetBufferInfo (SGChannel c, 
                                       short bufferNum,
                                       PixMapHandle *bufferPM,
                                       Rect *bufferRect, 
                                       GWorldPtr *compressBuffer,
                                       Rect *compressBufferRect);

c

Specifies the reference that identifies the channel for this operation.

bufferNum

Identifies the buffer. The sequence grabber component provides this value to your callback function.

bufferPM

Contains a pointer to a location that is to receive a handle to the pixel map that contains the image. Note that this pixel map may be offscreen. Do not dispose of this pixel map. If you do not want this information, set this parameter to nil.

bufferRect

Contains a pointer to a rectangle structure that is to receive the dimensions of the image's boundary rectangle. If you do not want this information, set this parameter to nil.

compressBuffer

Contains a pointer to a location that is to receive a pointer to the filter buffer for the image. The sequence grabber component returns this information only if your application has assigned a filter buffer to this video channel. You assign a filter buffer by calling the SGSetCompressBuffer function, which is described on page 5-84. Do not dispose of this buffer.

If you have not assigned a filter buffer, the sequence grabber sets the returned value to nil. If you do not want this information, set this parameter to nil.

compressBufferRect

Contains a pointer to a rectangle structure that is to receive the dimensions of the filter buffer for the image. The sequence grabber component returns this information only if your application has assigned a filter buffer to this video channel. You assign a filter buffer by calling the SGSetCompressBuffer function, which is described on page 5-84. If you have not assigned a filter buffer, the sequence grabber component returns an empty rectangle. If you do not want this information, set this parameter to nil.

RESULT CODE

paramErr

-50

Invalid parameter specified

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