Patent ID: 6373895
Filing Date: 2002-04-16
Classification: H04N

Abstract:
Video data compression apparatus in which successive group of images including intra-coded images and inter-coded images are encoded, said apparatus comprising:a trial encoder for encoding respective image data comprising at least a subset of image data of a current group of images to generate respective trial-encoded data for each respective image data, said respective trial-encoded data having respective quantities of data; a data quantity allocator, responsive to the quantities of trial-encoded data generated by said trial encoder, for allocating respective target quantities of output encoded data for said respective image data; and a final encoder for encoding said respective image data of said current group of images in accordance with the respective target quantities of output encoded data allocated to that respective image data by said data quantity allocator; wherein when a scene change is detected at a point within said respective image data by examining the normalized variance of at least a portion of said respective image data, said allocator sets to a default value a ratio of intra-coded image target quantity to inter-coded image target quantity; whereby the normalized variance is generated by dividing the variance of said portion of said respective image data by the mean variance for said portion and one or more similar portions.