THE RCELP SPEECH-CODING ALGORITHM

At bit rates between 4 and 16 kbit/s, many state-of-the-art speech cod ing algorithms fall into the class of linear-prediction based analysis -by-synthesis (LPAS) speech coders. At the lower bit rates the wavefor m-matching, on which LPAS coders rely, constrains the speech quality. To overcome this drawback, we present a coder (RCELP) that uses a gene ralization of the analysis-by-synthesis paradigm. This generalization relaxes the waveform-matching constraints without affecting speech qua lity. We describe several implementations at bit rates between 4 and 6 kbit/s. MOS tests show that a 6 kbit/s RCELP has a quality similar or better than the 13 kbit/s GSM full-rate coder, and a 4.4 kbit/s RCELP has a speech quality significantly better than the 4.8 kbit/s FS1016 standard.