SOUND BAND COMPRESSION SYSTEM

PURPOSE:To attain a high compression rate by applying DSI to a PCM signal converted from an analog sound signal and converting it further into a ADPCM signal. CONSTITUTION:After an inputted n-channel analog sound signal is converted into a digital PCM signal by a sound/PCM converting section 1, the result is subject to DSI by an output section 17 of a DSI section 3 and converted into an m-channel digital PCM signal. The digital PCM signal subject to DSI is band-compressed by a PCM/ADPCM converting section 5, but a forecast error is caused in case of an ADPCM system and the effect of forecast is effected on other signal if the interval between a signal and the other signal is short, and the effect is eliminated by a buffer time. Then the m-channel output signal of the PCM/ADPCM converting section 5 is multiplexed by a multiplex circuit 7 and outputted from an output circuit 11.