			err = CompressImage(GetPortPixMap(theGWorld), /* source image to compress */
								trackFrame, 			  /* bounds */
								codecNormalQuality,		  /* desired image quality */
								kAnimationCodecType,	  /* compressor identifier */
								imageDesc, 				  /* handle to Image Description Structure; will be resized by call */
								compressedDataPtr);		  /* pointer to a location to recieve the compressed image data */