Method for speech coding, method for speech decoding and their apparatuses Method for speech coding, method for speech decoding and their apparatuses
A high quality speech is reproduced with a small data amount in speech coding and decoding for performing compression coding and decoding of a speech signal to a digital signal. In speech coding method according to a code-excited linear prediction (CELP) speech coding, a noise level of a speech in a concerning coding period is evaluated by using a code or coding result of at least one of spectrum information, power information, and pitch information, and various excitation codebooks are used based on an evaluation result
1 . A speech encoding method for encoding a speech according to code-excited linear prediction (CELP) comprising:
evaluating a noise level of the speech in an encoding period based on an encoded result of analyzing power information; and
generating an excitation signal by using a time series vector obtained by adding a plurality of time series vectors which are weighted based on a result of the evaluating.
2 . A speech encoding apparatus for encoding a speech according to code-excited linear prediction (CELP) comprising:
an evaluating unit for evaluating a noise level of the speech in an encoding period based on an encoded result of analyzing power information; and
a generating unit for generating an excitation signal by using a time series vector obtained by adding a plurality of time series vectors which are weighted based on a result of the evaluating.