| 摘要 |
PURPOSE:To always attain the periodic refresh while the quantization characteristic is always in the best state by providing a coding control circuit making a quantization characteristic of a quantizer dense and generating a selection signal sending forcibly an output of an in-frame prediction device as a refresh signal. CONSTITUTION:In receiving a signal representing the memory occupancy sent from a buffer memory, it is inputted to a flip-flop 31 of a coding control circuit 10. The occupancy information is inputted to a comparator 32 synchronously with a clock signal in the unit of block lines and compared with a threshold value. A ROM 34 stores the quantization characteristic (step size) corresponding to the occupied quantity, decides the quantization characteristic in response to the inputted occupied quantity and outputs the signal. A selector selects an output of the device 2 so as to quantize and to send and the quantizer 1 applies quantization according to the quantization characteristic commanded by a coding control circuit 10. |
