TRANSCODING METHOD AND TRANSCODING APPARATUS

An apparatus comprises an input coded data buffer (2) for temporarily storing first coded data, an inverse quantization portion (4) for performing inverse quantization, a quantization portion (5) for requantising the inverse-quantized data by using new quantizer scale (NEW Q-scale), a DCT DC difference detector (8) for detecting a DC-component difference value of DCT coefficients of an I-picture from the first coded data, a DC difference mapping portion (9) for extracting a noticed region, which a person easily notices, according to the difference value, an edge MBA calculator (10), and a rate controller (1) for determining a new quantizer scale (NEW Q-scale) according to a result of the extraction of the noticed region and to the position of a slice, to which the data belongs, on a screen.