VORRICHTUNG UND VERFAHREN ZUR AUSWAHL DES CODIERUNGSMODUS IN EINEM BLOCKBASIERTEN CODIERUNGSSYSTEM

摘要

An apparatus and concomitant method for selecting a macroblock coding mode based upon the quantization scale selected for the macroblock. The total number of bits needed to code each macroblock consists of two parts, bits needed for coding motion vectors (320) and bits for coding the predictive residual (330). The number of bits for coding the motion vectors is generally obtained from a look-up table. The number of bits for coding the predictive residual is obtained by an estimation which assumes that the number of bits for encoding the predictive residuals is directly proportional to the value of its variance and inversely proportional to the value of quantizer steps (quantizer scale). Using this estimation, the total number of bits necessary to code a macroblock is calculated (340) and compared for each coding mode (350). By selecting the coding mode with the least number of bits, a near-optimal solution of low complexity for practical implementation is acquired.