Patent ID: 7295617

Claim:
An ADPCM decoder, comprising: an adaptive predictor which calculates a prediction signal from a quantization difference signal, the quantization difference signal including a mantissa part and an exponent part, the adaptive predictor including bit developing means which receives said mantissa part, and which bit-develops said mantissa part, bit shifting means which bit-shifts said bit-developed mantissa part in accordance with a value of said exponent part, overflow detecting means which is disposed as a most significant bit of said bit developing means and detects an overflow of said bit-shifted mantissa part, and prediction signal output means which, when said overflow detecting means detects the overflow of said bit-shifted mantissa part, replaces said bit-shifted mantissa part with a predetermined upper limit value and outputs said predetermined upper limit value as said prediction signal, and when the overflow of said bit-shifted mantissa part is not detected, outputs said bit-shifted mantissa part as said prediction signal; and an adder which adds said prediction signal and said quantization difference signal to provide a reproduction signal that corresponds to a decoded signal.