RATE CONTROLLER FOR HIGH EFFICIENCY CODING OF MOVING IMAGE SIGNAL

摘要

PURPOSE: To maximize the picture quality improvement effect of forward prediction by dividing a picture into N segments and predicting the degree of complexity of each segment in accordance with a preceding picture and controlling bit assignment of a quantizer by the operated result. CONSTITUTION: A segment complexity degree prediction part 33 predicts degrees αn of segments of a current picture in accordance with outputs of a quantizer 40 and a variable length encoder VLC 50. A rate control adjustment coefficient calculation part 34 takes degrees αn of segments as the input to calculate a rate control adjustment coefficient Kn and stores it in a memory 35. A reference quantization coefficient calculation part 31' takes the output state (degree dj of buffer filling) of an encoder buffer 2 and the coefficient Kn as the input to calculate a reference quantization coefficient Qj . An activity degree calculation part 32 takes the output of a data former 10 as the input to calculate a degree of activity of each macro block and operates degrees of activities and the reference quantization coefficient Qj to output a quantization coefficient Qj ' of a new frame, thus executing the rate control to maintain a certain transmission speed.