Method for synthesizing a frame of a speech signal with a computed stochastic excitation part
First Claim
1. Method for synthesizing a frame of a speech signal in a speech codec, in which a synthesis filter of a speech coder of the speech codec is supplied with an excitation vector consisting of an adaptive excitation part and a stochastic excitation part, which is taken from a previously calculated ideal Regular Pulse Excitation (RPE) sequence, comprising steps of:
- a) determining a position of a first non-zero pulse in the ideal RPE sequence,b) determining positions of a preselected number of strongest pulses in the ideal RPE sequence,c) determining amplitudes of the preselected number of strongest pulses, andd) determining signs of the preselected number of strongest pulses,wherein the positions, amplitudes, and signs furthermore being transmitted to a speech decoder of the speech codec in order to produce the stochastic excitation part there as well.
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Abstract
The invention describes one way of coding a speech signal without the elaborate searhing of a stochastic codebook. An "ideal" Regular Pulse Excitation (RPE) is used as the starting point for the method. The five strongest RPE pulses are quantized with equal amplitude and differ by their sign. The other RPE pulses are set to zero. This method, which is simple and can be carried out quickly, provides the same speech quality as with considerably more elaborate closed-loop methods.
19 Citations
4 Claims
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1. Method for synthesizing a frame of a speech signal in a speech codec, in which a synthesis filter of a speech coder of the speech codec is supplied with an excitation vector consisting of an adaptive excitation part and a stochastic excitation part, which is taken from a previously calculated ideal Regular Pulse Excitation (RPE) sequence, comprising steps of:
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a) determining a position of a first non-zero pulse in the ideal RPE sequence, b) determining positions of a preselected number of strongest pulses in the ideal RPE sequence, c) determining amplitudes of the preselected number of strongest pulses, and d) determining signs of the preselected number of strongest pulses, wherein the positions, amplitudes, and signs furthermore being transmitted to a speech decoder of the speech codec in order to produce the stochastic excitation part there as well. - View Dependent Claims (2, 3, 4)
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Specification
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Current AssigneeQualcomm, Inc.
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Original AssigneeNokia Mobile Phones UK Limited (Nokia Corporation)
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InventorsGortz, Udo
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Primary Examiner(s)Dorvil, Richemond
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Application NumberUS08/947,419Time in Patent Office895 DaysField of Search704/213, 704/219, 704/221, 704/222, 704/223, 704/264, 704/200, 704/266, 704/224, 704/225US Class Current704/223CPC Class CodesG10L 19/113 Regular pulse excitation
