System for speech encoding having an adaptive encoding arrangement
First Claim
1. A speech encoding system comprising:
- a detector for detecting whether an input speech signal generally has a triggering characteristic during an interval;
an encoder supporting at least one of a first encoding scheme and a first encoding scheme applicable to the speech signal for a frame associated with the interval, the first encoding scheme having a pre-processing procedure for processing the inputted speech signal to form a revised speech signal biased toward a generally ideal voiced and stationary characteristic; and
a selector for selecting one of the first encoding scheme and the second encoding scheme based upon the detection or absence of the triggering characteristic in the interval of the input speech signal.
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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
20 Claims
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1. A speech encoding system comprising:
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a detector for detecting whether an input speech signal generally has a triggering characteristic during an interval;
an encoder supporting at least one of a first encoding scheme and a first encoding scheme applicable to the speech signal for a frame associated with the interval, the first encoding scheme having a pre-processing procedure for processing the inputted speech signal to form a revised speech signal biased toward a generally ideal voiced and stationary characteristic; and
a selector for selecting one of the first encoding scheme and the second encoding scheme based upon the detection or absence of the triggering characteristic in the interval of the input speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A speech encoding system comprising:
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a detector for detecting whether an input speech signal generally has a generally voiced and generally stationary characteristic during an interval;
an encoder supporting at least one of a first encoding scheme and a second encoding scheme applicable to the speech signal for a frame associated with the interval, the second encoding scheme having long-term prediction procedure for processing the inputted speech signal on a sub-frame-by-subframe basis;
a selector for selecting one of the first encoding scheme and the second encoding scheme based upon said detection or absence of the generally voiced and generally stationary characteristic in the interval of the input speech signal. - View Dependent Claims (14, 15, 16)
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17. A speech encoding method comprising the steps of:
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detecting whether an input speech signal has a triggering characteristic during an interval;
selecting one of a first encoding scheme and a second encoding scheme, for application to the input speech signal for a frame associated with the interval, based upon said detection of the triggering characteristic; and
processing the inputted speech signal in accordance with the first encoding scheme to form a revised speech signal biased toward a generally ideal voiced and stationary characteristic if the triggering characteristic is detected in the input speech signal. - View Dependent Claims (18, 19, 20)
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Specification