Inside Macintosh: QuickTime Components
The compression information structure defines the characteristics of a buffer that contains a captured image that has been compressed. Callback functions use compression information structures to exchange information about compressed images. For example, the compress-complete function must format a compression information record whenever a video frame is compressed (see "Video Channel Callback Functions," for more information about the compress-complete callback function). The SGCompressInfo data type defines a compression information structure.
struct SGCompressInfo {
Ptr buffer; /* buffer for compressed image */
unsigned long bufferSize; /* bytes of image data in buffer */
unsigned char similarity; /* relative similarity */
unsigned char reserved; /* reserved--set to 0 */
};
typedef struct SGCompressInfo SGCompressInfo;