Selective application of speech coding techniques to input signal segments

摘要

A speech coding method and apparatus which selectively applies speech coding techniques to time segments of speech information signals, such as, e.g., pitch cycle waveforms is disclosed. A speech information signal comprising N signal segments is coded with a first speech coder to provide a first coded representation for each of the N signal segments. A second speech information signal reflecting speech information not coded by the first coder is determined for each of one or more of the N signal segments. In addition to coding the N first speech information signal segments with the first speech coder, M of the second speech information signals are coded with a second speech coder, where 1≦M≦N-1. The selective coding of M of the second speech information signals is done responsive a coding criterion. By selective use of the second speech coder, the number of bits needed to represent speech information may be reduced, or alternatively, better performance may be obtained without an increase in bit rate. The first and second speech coders may be any of those known in the art.