Speech coding system and method including spectral quantizer
First Claim
1. A method for quantizing line spectral frequencies representing the spectral envelope of frames of a speech signal, said method comprising the steps of:
- vector quantizing the LSFs for even numbered frames using a particular number of those bits which are available for LSF quantization;
quantizing the LSFs for odd numbered frames by interpolation, said interpolation comprising the steps of(a) determining the spectral sensitivity for each LSF in said odd numbered frame;
(b) allocating, among the LSFs in said odd numbered frames, the remainder of said number of bits available, said allocation being such as to provide more bits to those of said LSFs in said odd numbered frames which have a large amount of spectral sensitivity than are provided to those LSFs having a lesser amount of spectral sensitivity; and
(c) quantizing said LSFs in said odd numbered frames using the allocated number of bits.
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Abstract
A speech coding system and associated method relies on a speech encoder and a speech decoder. The encoder includes a spectral quantizer for computing line spectral frequencies (LSFs) for respective frames of speech and for quantizing the LSFs to obtain a minimum bit representation of a spectral envelope of each respective frame of speech. For even numbered frames of speech the LSFs are quantized using a vector quantization technique. For odd numbered frames of speech samples the LSFs are quantized using a dynamic bit allocation (DBA) method. The dynamic bit allocation method determines an interpolation factor for interpolating between the LSFs of the previous and next frames. According to the dynamic bit allocation method the most perceptually important LSFs are represented by relatively more bits, while the least perceptually important LSFs are represented by relatively fewer bits. The system and associated method thereby reduces an overall bit rate required to represent, transmit or store the speech samples.
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Citations
1 Claim
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1. A method for quantizing line spectral frequencies representing the spectral envelope of frames of a speech signal, said method comprising the steps of:
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vector quantizing the LSFs for even numbered frames using a particular number of those bits which are available for LSF quantization; quantizing the LSFs for odd numbered frames by interpolation, said interpolation comprising the steps of (a) determining the spectral sensitivity for each LSF in said odd numbered frame; (b) allocating, among the LSFs in said odd numbered frames, the remainder of said number of bits available, said allocation being such as to provide more bits to those of said LSFs in said odd numbered frames which have a large amount of spectral sensitivity than are provided to those LSFs having a lesser amount of spectral sensitivity; and (c) quantizing said LSFs in said odd numbered frames using the allocated number of bits.
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Specification
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- Resources
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Current AssigneeLockheed Martin Corporation (Martin Marietta Corporation)
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Original AssigneeLockheed Martin Corporation (Martin Marietta Corporation)
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InventorsGrabb, Mark Lewis, Zinser, Richard Louis Jr., Koch, Steven Robert, Brooksby, Glen William
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Primary Examiner(s)Hudspeth, David R.
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Assistant Examiner(s)Smits, Talivaldis Ivars
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Application NumberUS09/114,659Time in Patent Office743 DaysField of Search704/206, 704/219, 704/222, 704/229US Class Current704/219CPC Class CodesG10L 19/07 Line spectrum pair [LSP] vo...
