Application and development of speech codingApplication and development of speech coding.docVIP

voice coding Speech coding (speech coding) the simulation process voice signals into digital signals. Is an important technology in digital communication. Objective in order to keep a certain algorithm complexity and communication delay, using the channel capacity as little as possible to transfer as much as possible voice quality. High quality low bit rate speech coding technology has been widely applied in all kinds of communication network. In recent years, in order to adapt to the development of digital mobile communication network, some suitable for mobile channel coding technology is presented, including the European GSM system using the regular pulse excitation-long term prediction coding (RPE-LTP) and the United States of America Vector and excitation linear predictive coding (VSELP) is proposed. Classification of speech coding technique is usually divided into 3 categories: waveform coding, parametric coding and hybrid coding, the waveform coding and parameter coding is one of 2 basic types. Waveform coding will directly transform in time domain signal into a digital code, its purpose is as far as possible to accurately reproduce the original speech waveform. The basic principle of waveform coding is on the time axis to analog voice according to certain rate sampling, then the amplitude of stratified sample quantization, and expressed in code. Decoding is the inverse process, a sequence of digital will receive recovery through the decoding and the filtered analog signal. For coding signal bit rate high (for example: from 16 to 64 kbit\/s), waveform coding techniques can provide very good voice quality. But for low bit rate speech coding signal (i.e. bit rate of less than 16 kbit\/s), waveform coding voice quality decreased significantly. Therefore, applied waveform coding communication in the requirement of signal bandwidth is not too strict. But the mobile communication is quite nervous on the frequency resource, this kind of coding method is not suitab