Apparatus and method for coding a moving picture

摘要

A moving picture coding apparatus is provided which is capable of controlling a bit rate of output codes so as not to exceed a target bit rate and reducing noises in a decoded image. The apparatus comprises: a converter 13 for converting prediction errors of a plurality of pixel data into frequency components on a block basis; a quantizer 14 for quantizing converted prediction errors with reference to a quantization table; a dequantizer 15 for dequantizing quantized prediction errors with reference to a quantization table; a coder 18 for coding the quantized prediction errors to generate codes; an output buffer 19 for buffering the codes; a buffer checker 20 for checking a code occupied ratio in the output buffer; a plurality of quantization tables; and a quantization table selector 21 for selecting on quantization table from the plurality of quantization tables in accordance with the code occupied ratio. The quantizer employs the selected on quantization table, and the dequantizer employs a quantization table determined for a group of pictures.