Method and apparatus for high performance low bit-rate coding of unvoiced speech
AssigneeQUALCOMM Incorporated
InventorPengjun Huang
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Abstract
A low-bit-rate coding technique for unvoiced segments of speech, without loss of quality compared to the conventional Code Excited Linear Prediction (CELP) method operating at a much higher bit rate. A set of gains are derived from a residual signal after whitening the speech signal by a linear prediction filter. These gains are then quantized and applied to a randomly generated sparse excitation. The excitation is filtered, and its spectral characteristics are analyzed and compared to the spectral characteristics of the original residual signal. Based on this analysis, a filter is chosen to shape the spectral characteristics of the excitation to achieve optimal performance.
Claims1
A speech coder for encoding unvoiced segments of speech, comprising:
- means for performing a first filtering of the scaled random noise;
- means for comparing the filtered noise with the residual signal;
- means for performing a second filtering of the random noise based on the comparison;
- and
- means for providing multi-stage vector quantization.
Dependencies are inferred from the claim text.