The method comprises the following steps: during the first pass, a memorization of the M best coding modes and their coding parameters per image macroblock, during the second pass, a calculation, according to the new quantization step determined by the regulating algorithm according to the parameters memorized, among the M coding modes memorized, of the coding mode minimising the bitrate-distortion criterion, to select it, a coding according to the selected coding mode. The applications relate to the compression of data.