Predictive coding of speech at low bit rates
Abstract
Work being done on adaptive predictive coding of speech signals is reviewed, especially that on achieving high speech quality at low bit rates (less than 10 kbits/s). Generalizations of predictive coding for minimizing subjective distortion in the reconstructed speech signal at the receiver are presented. It is noted that the quantizer in predictive coders quantizes its input on a sample-by-sample basis. Such sample-by-sample (instantaneous) quantization is seen as creating difficulties in realizing an arbitrary noise spectrum, particularly at low bit rates. A new class of speech coders is described. These coders not only make it possible to realize the precise optimum noise spectrum that is crucial to achieving very low bit rates; they also represent the important first step in bridging the gap between waveform coders and vocoders without suffering from their limitations.
- Publication:
-
IEEE Transactions on Communications
- Pub Date:
- April 1982
- Bibcode:
- 1982ITCom..30..600A
- Keywords:
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- Signal Distortion;
- Signal Encoding;
- Speech;
- Transmission Efficiency;
- Voice Communication;
- Channel Capacity;
- Coders;
- Noise Spectra;
- Vocoders;
- Communications and Radar