Codebook sharing for LSF quantization
First Claim
1. A multi-rate speech coding system capable of operating in one of a first coding rate and a second coding rate, the multi-rate speech coding system comprising:
- a vector quantizer (VQ) for quantizing line spectral frequencies (LSFs), the VQ including a first VQ stage and a second VQ stage;
a processing circuitry configured to;
determine whether the multi-rate speech coding system is configured to operate in the first coding rate or the second coding rate;
quantize the LSFs using the first VQ stage and not the second VQ stage when the processing circuitry determines that the multi-rate speech coding system is configured to operate in the first coding rate; and
quantize the LSFs using both the first VQ stage and the second VQ stage when the processing circuity determines that the multi-rate speech coding system is configured to operate in the second coding rate.
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Accused Products
Abstract
In accordance with one aspect of the invention, a selector supports the selection of a first encoding scheme or the second encoding scheme based upon the detection or absence of the triggering characteristic in the interval of the input speech signal. The first encoding scheme has a pitch pre-processing procedure for processing the input speech signal to form a revised speech signal biased toward an ideal voiced and stationary characteristic. The pre-processing procedure allows the encoder to fully capture the benefits of a bandwidth-efficient, long-term predictive procedure for a greater amount of speech components of an input speech signal than would otherwise be possible. In accordance with another aspect of the invention, the second encoding scheme entails a long-term prediction mode for encoding the pitch on a sub-frame by sub-frame basis. The long-term prediction mode is tailored to where the generally periodic component of the speech is generally not stationary or less than completely periodic and requires greater frequency of updates from the adaptive codebook to achieve a desired perceptual quality of the reproduced speech under a long-term predictive procedure.
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Citations
12 Claims
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1. A multi-rate speech coding system capable of operating in one of a first coding rate and a second coding rate, the multi-rate speech coding system comprising:
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a vector quantizer (VQ) for quantizing line spectral frequencies (LSFs), the VQ including a first VQ stage and a second VQ stage; a processing circuitry configured to; determine whether the multi-rate speech coding system is configured to operate in the first coding rate or the second coding rate; quantize the LSFs using the first VQ stage and not the second VQ stage when the processing circuitry determines that the multi-rate speech coding system is configured to operate in the first coding rate; and quantize the LSFs using both the first VQ stage and the second VQ stage when the processing circuity determines that the multi-rate speech coding system is configured to operate in the second coding rate. - View Dependent Claims (2, 3, 4, 5, 11)
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6. A quantization method for use by a multi-rate speech coding system capable of operating in one of a first coding rate and a second coding rate, multi-rate speech coding system including a vector quantizer (VQ) for quantizing line spectral frequencies (LSFs), the VQ including a first VQ stage and a second VQ stage, the quantization method comprising:
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determining whether the multi-rate speech coding system is operating in the first coding rate or the second coding rate; quantizing the LSFs using the first VQ stage and not using the second VQ stage when the determining determines that the multi-rate speech coding system is configured to operate in the first coding rate; and quantizing the LSFs using both the first VQ stage and the second VQ stage when the determining determines that the multi-rate speech coding system is configured to operate in the second coding rate. - View Dependent Claims (7, 8, 9, 10, 12)
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Specification