ADAPTIVE FORECASTING ENCODING SYSTEM

摘要

PURPOSE:To shorten an encoding and decoding processing time and to improve an S/N ratio by detecting the periodic locality of the residual electric power from a locally decoded residual signal, and adapting the number of quantized bits of the residual signal backward on the basis of the detection result. CONSTITUTION:The difference signal (residual signal) between an input signal X(n) from an input terminal 21 and a forecasted signal X'(n) is generated by a subtracter 22 and quantized by a quantizer 23, whose output is sent as a code sequence I(n) to an output buffer 24. The code sequence I(n) is quantized reversely by a reverse quantizer 25 simultaneously, and an adder 26 adds its output e'(n) and the forecasted signal X'(n) together to input a locally decoded signal X''(n) to a forecasting device 27. The quantization width and number of quantized bits of the quantizer 23 and the coefficient of the forecasting device 27 are adapted on the basis of the decoded residual signal e'(n).