| 摘要 |
<p>A DCT coefficient outputted from a DCT circuit (21) is quantized by quantization circuits (22 to 25) with different quantization coefficients, and the code length of each quantized output is determined by each code length calculation circuit (28 to 31). The code lengths obtained from calculation circuits (28 to 31) are summed for one screen by adders (33 to 26). In this way, the respective totals of measurement bits corresponding to a plurality of quantization coefficients are obtained. A comparator (37), multipliers (38,39) and an adder (40) select two, close to the target total, from the totals obtained, and determine a scale factor for obtaining a quantization coefficient coresponding to the target total of bits. A quantization coefficient generator (27) generates an optimum quantization coefficient in the next or second scanning from this scale factor. <IMAGE></p> |
