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Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Image Compression Manager Functions / Changing Sequence-Decompression Parameters

GetDSequenceImageBuffer

The GetDSequenceImageBuffer function helps you determine the location of the offscreen image buffer allocated by the decompressor.

pascal OSErr GetDSequenceImageBuffer (ImageSequence seqID,
                                        GWorldPtr *gworld);

seqID

Contains the unique sequence identifier that was returned by the DecompressSequenceBegin function (described on page 3-107).

gworld

Contains a pointer to a field to receive a pointer to the structure of type GWorld describing the graphics world for the image buffer. If the decompressor has allocated an offscreen image buffer, the decompressor returns an appropriate GWorldPtr in the field referred to by this parameter. If the decompressor has not allocated a buffer, the function returns an error result code.

You should not dispose of this graphics world--the returned pointer refers to a buffer that the Image Compression Manager is using. It is disposed of for you when the CDSequenceEnd function is called. For details on CDSequenceEnd, see page 3-113.

DESCRIPTION

The decompressor uses this buffer when decompressing a sequence that was temporally compressed. You cause the decompressor to use an image buffer by setting the codecFlagUseImageBuffer flag to 1 in the flags parameter to the DecompressSequenceBegin function.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified