System and method for enhanced speech quality in voice storage and retrieval systems
First Claim
1. A method for storage and retrieval of digital voice data, comprising the steps of:
- receiving input voice waveforms;
converting said input voice waveforms into digital voice data;
encoding said digital voice data into a plurality of parameters for each of a plurality of frames of said digital voice data;
storing said plurality of parameters in a storage memory;
reading said plurality of parameters from said storage memory after a conclusion of said steps of (a) receiving input voice waveforms, (b) converting said input voice waveforms, (c) encoding said digital voice data, and (d) storing said plurality of parameters in a storage memory; and
smoothing said plurality of parameters to remove discontinuities from said plurality of parameters after said step of reading said plurality of parameters from said storage memory;
wherein, for one or more of said plurality of parameters, said step of smoothing comprises;
comparing a first parameter in a first frame with like parameters from a plurality of prior frames and a plurality of subsequent frames to determine if said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames; and
replacing said first parameter with a new value if said step of comparing indicates that said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames.
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Abstract
A digital voice data storage and retrieval system using a low bit rate encoder which provides enhanced speech signal quality while also reducing memory size requirements. The system comprises a voice coder/decoder which preferably includes a digital signal processor (DSP) and also preferably includes a local memory. During encoding of the voice data, the voice coder/decoder receives voice input waveforms and generates a parametric representation of the voice data. A storage memory is coupled to the voice coder/decoder for storing the parametric data. During decoding of the voice data, the voice coder/decoder receives the parametric data from the storage memory and reproduces the voice waveforms. According to the invention, an interframe smoothing method is performed on the parametric data after encoding of all of the speech data has completed and the parametric data has been stored in the storage memory. The interframe smoothing is performed either in the background after the coding process has completed or in real time during the decoding process immediately prior to converting the parametric data back to signal waveforms. Since all of the voice input data has already been converted to parametric data and stored in memory, parametric data from a virtually unlimited number of prior and successive frames is available for use by the smoothing algorithm. Therefore, the present invention provides more accurate smoothing and provides enhanced speech signal quality over prior systems.
45 Citations
44 Claims
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1. A method for storage and retrieval of digital voice data, comprising the steps of:
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receiving input voice waveforms; converting said input voice waveforms into digital voice data; encoding said digital voice data into a plurality of parameters for each of a plurality of frames of said digital voice data; storing said plurality of parameters in a storage memory; reading said plurality of parameters from said storage memory after a conclusion of said steps of (a) receiving input voice waveforms, (b) converting said input voice waveforms, (c) encoding said digital voice data, and (d) storing said plurality of parameters in a storage memory; and smoothing said plurality of parameters to remove discontinuities from said plurality of parameters after said step of reading said plurality of parameters from said storage memory; wherein, for one or more of said plurality of parameters, said step of smoothing comprises; comparing a first parameter in a first frame with like parameters from a plurality of prior frames and a plurality of subsequent frames to determine if said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames; and replacing said first parameter with a new value if said step of comparing indicates that said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A digital voice storage and retrieval system which provides enhanced speech quality, comprising:
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a memory store; a processor which receives input voice waveforms, generates a plurality of parameters representative of said input voice waveforms, and stores said plurality of parameters in said memory store, wherein said input voice waveforms can be partitioned into a plurality of frames and said processor generates said plurality of parameters for said plurality of frames of said input voice waveforms; a local memory coupled to said processor for storing a first plurality of said plurality of parameters, wherein said first plurality of parameters includes a first parameter in a first frame being smoothed and like parameters from a plurality of prior and subsequent frames relative to said first frame; wherein said processor reads said first plurality of parameters from said memory store and stores said first plurality of parameters in said local memory after a conclusion of (a) receiving the input voice waveforms, (b) generating the plurality of parameters, and (c) storing the plurality of parameters in said memory store; wherein said processor performs a smoothing operation on said first plurality of parameters in said local memory after reading said first plurality of parameters from said memory store and storing said first plurality of parameters in said local memory, wherein said smoothing operation removes at least one discontinuity from said first plurality of parameters; wherein said processor performs smoothing operations on said first parameter in said local memory using said like parameters from said plurality of prior and subsequent frames. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. A method for storage and retrieval of digital parametric data, comprising the steps of:
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receiving input digital data; encoding said digital data into a plurality of parameters for each of a plurality of frames of said digital data; storing said plurality of parameters in a storage memory; reading said plurality of parameters from said storage memory after a conclusion of said steps of (a) receiving input digital data, (b) encoding said digital data, and (c) storing said plurality of parameters in a storage memory; and smoothing said plurality of parameters to remove discontinuities from said plurality of parameters after said step of reading said plurality of parameters from said storage memory; wherein said smoothing comprises; comparing a first parameter in a first frame with like parameters from a plurality of prior frames and a plurality of subsequent frames to determine if said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames; and replacing said first parameter with a new value if said step of comparing indicates that said first parameter varies from said like parameters from said plurality of prior frames and said plurality of subsequent frames. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A digital data storage and retrieval system which provides enhanced speech quality, comprising:
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a processor which receives input digital data and generates a plurality of parameters representative of said input digital data, wherein said input digital data can be partitioned into a plurality of frames and said processor generates said plurality of parameters for said plurality of frames of said input digital data; a memory store coupled to said processor for storing said plurality of parameters; a local memory coupled to said processor for storing a first plurality of said plurality of parameters, wherein said first plurality of parameters includes a first parameter in a first frame being smoothed and like parameters from a plurality of prior and subsequent frames relative to said first frame; wherein said processor reads said first plurality of parameters from said memory store and stores said first plurality of parameters in said local memory; wherein said processor performs a smoothing operation on said first parameter in said local memory after reading said first plurality of parameters from said memory store and storing said first plurality of parameters in said local memory; wherein said processor performs said smoothing operation on said first parameter in said local memory using said like parameters from said plurality of prior and subsequent frames. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44)
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Specification