Patent ID: 7095784
Filing Date: 2006-08-22
Classification: H04N

Abstract:
1. A method for rate control in moving picture compression using bit allocation with initial quantization step size estimation at picture level, the method comprising the steps of: calculating a total activity measure for a current picture to be encoded in a set of consecutive pictures of a video sequence; estimating a complexity measure of the current picture based on the total activity measure of the current picture and an activity-to-complexity ratio of a previously encoded picture of the same type; updating an instantaneous complexity measure for the set of consecutive pictures with the estimated complexity measure of the current picture; allocating a target bit budget to the current picture depending on the estimated complexity measure and the instantaneous complexity measure; determining an initial value for an average quantization step size to be used to encode the current picture based on a function of the total activity measure of the current picture, the target bit budget for the current picture and the activity-to-complexity ratio of the previously encoded picture of the same type; encoding the current picture in the video sequence on the basis of the determined initial value for the average quantization step size; and after encoding the current picture, computing the activity-to-complexity ratio for the current picture based on the total activity measure, actual bits consumed by the current picture and the average of actual quantization step sizes used to encode the current picture; wherein the activity-to-complexity ratio of the current picture varies directly with the total activity measure of the current picture and inversely with the actual consumed bits and the average of actual quantization step sizes used to encode the current picture.