LOW DELAY CODE DRIVING TYPE LINEAR ENCODING METHOD

摘要

PURPOSE:To obtain the encoding method which is hardly affected on a decoding side by a bit error on a transmission line. CONSTITUTION:A filter coefficient which is linearly predicted from the decoded speech waveform of a past frame is set in a synthesizing filter and two kind of exciting sources for a pitch period component and a noise component are used in addition to the synthesizing filter to perform predictive encoding. The decoded speech of the past frame is passed through a reverse filter to find a residue waveform, whose autocorrelation is found to obtain plural pitch period candidates Ti (i=1-m) in decreasing order; and waveforms of one frame from points traced back by Ti, 2Ti, and 3Ti are extracted from the residue waveform respectively and those three waveforms are added to obtain a pitch period candidate. Then the pitch period component having minimum distortion is selected among (mn) pitch period candidates for a current frame.