摘要 |
PURPOSE:To save memory capacity by extracting a difference signal of at least two channels among plural channels, decreasing the sampling frequency to quantize the signal and compressing the signal. CONSTITUTION:A signal s1 of L channel and a signal s2 of R channel are inputted to a subtraction circuit 1 and the signal s1 of L channel is inputted to an 8-bit A/D converter 2 whose sampling frequency is f1. The subtraction circuit 1 subtracts the signal s2 of R channel from the signal s1 of L channel and outputs its difference signal to an 8-bit A/D converter 3 whose sampling frequency is f2. The relation of f1>f2 exists between the sampling frequencies f1 and f2. Then a digital signal subjected to compression is stored in memories 4, 5 as PCM data. Thus, the quantity of information is reduced in comparison with that of the case sampling the channels L, R singly and when the signal is converted into a digital signal and stored in the memory, the memory capacity is reduced. |