Method and apparatus for performing speech frame encoding mode selection in a variable rate encoding system
First Claim
1. An apparatus for selecting an encoding rate from a predetermined set of encoding rates for encoding a frame of speech including a plurality of speech samples, comprising:
- mode measurement means, responsive to said speech samples and to at least one signal derived from said speech samples, for generating a set of parameters indicative of characteristics of said frame of speech; and
rate determination logic means for receiving said set of parameters, for determining the psychoacoustic significance of said speech samples in accordance with said set of parameters and for selecting an encoding rate from said predetermined set of encoding rates using predetermined rate selection rules, wherein said rate selection rules select said encoding rate which allocates a first number of bits for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein said rate selection rules select said encoding rate which allocates a second number of bits for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits.
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Abstract
A method and apparatus for the selection of an encoding mode for speech frames in a variable rate encoding system. For each speech frame, the method and apparatus selects the encoding mode which provides for rate efficient coding. A mode measurement element receives a speech signal and a signal derived from the same speech signal, and generates a set of parameters which are ideally suited for operational mode selection. Rate determination logic receives the set of parameters and selects an encoding rate using predetermined selection rules. The selection rules further distinguish between unvoiced speech and temporally masked speech, which are encoded at the same rate but with different encoding strategies.
185 Citations
33 Claims
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1. An apparatus for selecting an encoding rate from a predetermined set of encoding rates for encoding a frame of speech including a plurality of speech samples, comprising:
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mode measurement means, responsive to said speech samples and to at least one signal derived from said speech samples, for generating a set of parameters indicative of characteristics of said frame of speech; and rate determination logic means for receiving said set of parameters, for determining the psychoacoustic significance of said speech samples in accordance with said set of parameters and for selecting an encoding rate from said predetermined set of encoding rates using predetermined rate selection rules, wherein said rate selection rules select said encoding rate which allocates a first number of bits for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein said rate selection rules select said encoding rate which allocates a second number of bits for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a communication system wherein a remote station communicates with a central communication center, a sub-system for dynamically changing the transmission rate of a frame of speech transmitting from said remote station, comprising:
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mode measurement means, responsive to said speech frame and to a signal derived from said speech frame, for generating a set of parameters indicative of characteristics of said speech frame; and rate determination logic means for receiving said set of parameters for determining the psychoacoustic significance of said speech samples in accordance with said set of parameters, and for receiving a rate command signal for generating at least one threshold value in accordance with said rate command signal, comparing at least one parameter of said set of parameters with said at least one threshold value and selecting an encoding rate in accordance with said comparison, wherein said encoding rate which allocates a first number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein said encoding rate which allocates a second number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits.
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12. An apparatus for selecting an encoding rate from a predetermined set of encoding rates for encoding a frame of speech including a plurality of speech samples, comprising:
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a mode measurement calculator that generates a set of parameters indicative of characteristics of said frame of speech in accordance with said speech samples and a signal derived from said speech samples; and a rate determination logic for receiving said set of parameters, for determining the psychoacoustic significance of said speech samples in accordance with said set of parameters, and selecting an encoding rate from said predetermined set of encoding rates, wherein said encoding rate which allocates a first number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein said encoding rate which allocates a second number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. In a communication system wherein a remote station communicates with a central communication center, a sub-system for dynamically changing the transmission rate of a frame of speech transmitting from said remote station, comprising:
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a mode measurement calculator that generates a set of parameters indicative of characteristics of said frame of speech in accordance with said speech samples and a signal derived from said speech samples; and a rate determination logic that receives said set of parameters for determining the psychoacoustic significance of said speech samples in accordance with said set of parameters, and for receiving a rate command signal for generating at least one threshold value in accordance with said rate command signal, comparing at least one parameter of said set of parameters with said at least one threshold value and selecting an encoding rate in accordance with said comparison, wherein said encoding rate which allocates a first number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein said encoding rate which allocates a second number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits.
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23. A method for selecting an encoding rate of a predetermined set of encoding rates for encoding a frame of speech including a plurality of speech samples, comprising the steps of:
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generating a set of parameters indicative of characteristics of said frame of speech in accordance with said speech samples and with a signal derived from said speech samples; and selecting an encoding rate from said predetermined set of encoding rates in accordance with said set of parameters, said set of parameters for determining the psychoacoustic significance of said speech samples, wherein said encoding rate which allocates a first number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein select said encoding rate which allocates a second number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. In a communication system wherein a remote station communicates with a central communication center, a method for dynamically changing the transmission rate of said remote station comprising the steps of:
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generating a set of parameters indicative of characteristics of said frame of speech in accordance with said speech frame and a signal derived from said speech frame, said set of parameters for determining the psychoacoustic significance of said speech samples; receiving a rate command signal; generating at least one threshold value in accordance with said rate command signal; comparing at least one parameter of said set of parameters with said at least one threshold value; and selecting an encoding rate in accordance with said comparison, wherein said encoding rate which allocates a first number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of greater psychoacoustic significance and wherein select said encoding rate which allocates a second number of bits is selected for the encoding of said speech samples when said speech samples are determined to be of a lesser psychoacoustic significance and wherein said first number of bits is greater than said second number of bits.
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Specification