Patent ID: 8300711

Claim:
An adaptive differential pulse-code modulation-demodulation (ADPCM) system, comprising: a modulation module, coupled to a communication network, for modulating an analog audio input signal into a data packet to be transmitted to the communication network, wherein the data packet comprises a plurality of ADPCM digital data, and an initial value and a scale factor associated with the ADPCM digital data, the modulation module comprising: a quantizer, for sampling the analog audio input signal with a fixed sampling frequency into a plurality of uncompressed digital sampled values; a differential calculation unit, coupled to the quantizer, for generating a plurality of digital differences by respectively subtracting an initial value from the plurality of digital sampled values; a scale factor generator, coupled to the differential calculation unit, for estimating the scale factor associated with the data packet according to a difference between the initial value and a greatest sampled value of the digital sampled values within a predetermined period; a modulator, coupled to the differential calculation unit, for modulating the plurality of digital values into the ADPCM digital data; a packet generator, coupled to the modulator and the scale factor generator, for packing the ADPCM digital data within the predetermined period, the initial value and the scale factor into the data packet; and a transmitter, coupled to the packet generator, for transmitting the data packet to the communication network; and a demodulation module, coupled to the communication network, for receiving the data packet and demodulating the ADPCM digital data of the data packet according to the initial value and the scale factor to reconstruct an analog audio output signal.