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Chapter 8 - Video Digitizer Components / Video Digitizer Components Reference

Video Digitizer Component Functions / Controlling Digitization

VDSetupBuffers

The VDSetupBuffers function allows applications to define output buffers for use with asynchronous grabs. Video digitizer components extract information about the spatial characteristics of the video destinations from these buffers.

pascal VideoDigitizerError VDSetupBuffers 
                           (VideoDigitizerComponent ci,
                            VdigBufferRecListHandle bufferList);

ci

Specifies the video digitizer component for the request. Applications obtain this reference from the Component Manager's OpenComponent function.

bufferList

Contains a handle to a list of output buffers. This buffer list is contained in a buffer list structure. This structure is described in "The Buffer List Structure" on page 8-22. Note that the video digitizer component makes a copy of the buffer list--you may dispose of this handle when the function returns to your application.

WARNING

If you are developing a video digitizer component, note that the matrix field in the buffer list structure contains a pointer to the matrix structure. It is your responsibility to copy that matrix structure.

SPECIAL CONSIDERATIONS

Applications must define the output buffers before starting an asynchronous grab.

RESULT CODES

noErr	0	No error
digiUnimpErr	-2201	Function not supported
qtParamErr	-2202	Invalid parameter value
badDepth	-2207	Digitizer cannot accommodate specified depth
noDMA	-2208	Digitizer cannot use DMA to this destination

SEE ALSO

Applications instruct digitizer components to grab a single frame by calling the VDGrabOneFrameAsync function, which is described on page 8-56.

Applications free these buffers by calling the VDReleaseAsyncBuffers function, which is described next.

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