| 摘要 |
PURPOSE:To improve the quantization characteristic by assuming a quantization code at sampling point of time after each sampling point of time and selecting a quantizing code minimizing error power of a reproducing signal series in the quantization signal. CONSTITUTION:Adaptive forecast coding sections 1-1-1-k are operated at each sampling point of time to an input signal by using different step size revision coefficient M1-Mk and an error power calculator 2 decides an adaptive forecast coding section having a step size revision coefficient with minimum error power in the unit of frames. Then a command signal is outputted from an optimum quantization deciding device 3, a selection section 4 selects a quantized value of the error signal from the adaptive forecast coding section commanded by the command signal and the quantized value of the error signal and the command signal are multiplexed and outputted via a multiplex section 5. In quantizing the error signal at each sample point of time in this way, the quantization code is decided while taking the effect of the quantization code on the succeeding quantization characteristic into account as well as the preceding information, then the quantization characteristic is improved. |
