Apparatus for variable bit rate control in video compression and target bit allocator thereof

An apparatus for variable bit rate control in moving picture compression, comprising:

• a motion estimation unit receiving a current picture to be encoded in a set of consecutive pictures of a video sequence, for calculating a total activity measure for the current picture to be encoded;
• a complexity estimator for 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 in the set of consecutive pictures;
• a target bit allocator updating an instantaneous complexity measure for the set of consecutive pictures with the complexity measure of the current picture, and calculating an instantaneous rate of the set of consecutive pictures based on a predetermined mean rate, the instantaneous complexity measure and a statistical complexity measure of the set of consecutive pictures, for allocating a target bit budget to the current picture depending on the complexity measure of the current picture, the instantaneous rate and the instantaneous complexity measure of the set of consecutive pictures;
• and
• a parameter updater for computing the activity-to-complexity ratio for the current picture based on the total activity measure, actual bits consumed by the current picture and an average of actual quantization step sizes used to encode the current picture, and calculating the statistical complexity measure for the set of consecutive pictures based on the complexity measure of 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.