An improved MPEG-4 rate control algorithm

In this paper, we present an improved rate-control algorithm based on the quadratic R-D model over a CBR channel. Key features of the present work are: 1) the bits allocated to each P-frame or B-frame are in proportion to its distance from the end of this GOP; 2) the target buffer level is changeable at the end of each GOP (5 P-frame or B-frame), the target buffer level is linearly reduced from 1/2 to 1/4 of buffer size, to other frames, the target buffer level is set to 1/2 of buffer size; 3) a selective and judicious use of the reduced resolution (RRV) mode, in addition to a modulation of the quantization scale parameter, to control the average long-term bit rate. Experimental results with different video sequences of varied complexity, encoded at low bit rates show the efficacy of the proposed algorithm than MPEG-4 Q2 rate-control scheme.