Method and apparatus for efficient multiband celp wideband speech and music coding and decoding
First Claim
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1. A method for encoding and decoding sound, comprising the steps of:
- analyzing an input waveform and computing the linear prediction coefficients for a portion of the input waveform;
classifying the input waveform as one of a group comprising speech and music;
generating a first plurality of codebooks, each having an output, where each codebook is associated with a frequency band;
generating at least one first adaptive codebook having an output;
coupling the output of the first plurality of codebooks and the output of the at least one first adaptive codebook together to create a composite waveform;
synthesis filtering the composite waveform;
perceptually weighting the input waveform;
perceptually weighting the synthesis filtered composite waveform;
differencing the perceptually weighted synthesis filtered composite waveform from the perceptually weighted input waveform to form an output waveform;
searching through the first plurality of codebooks and the adaptive codebook to minimize the errors in the output waveform; and
decoding the output waveform using a second plurality of codebooks and at least one second adaptive codebook.
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Abstract
A method of digitally compressing speech and music by use of multiple band ("multiband") fixed excitations stored in codebooks. The use of multiband fixed excitations, along with a coupling method for interconnecting the excitation codebooks and adaptive codebooks and for generating the composite excitation signal, improve the long-term and short-term prediction, and the use of voice-music classification allows the coding structure to be adapted to the statistical character of the audio signal.
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Citations
7 Claims
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1. A method for encoding and decoding sound, comprising the steps of:
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analyzing an input waveform and computing the linear prediction coefficients for a portion of the input waveform; classifying the input waveform as one of a group comprising speech and music; generating a first plurality of codebooks, each having an output, where each codebook is associated with a frequency band; generating at least one first adaptive codebook having an output; coupling the output of the first plurality of codebooks and the output of the at least one first adaptive codebook together to create a composite waveform; synthesis filtering the composite waveform; perceptually weighting the input waveform; perceptually weighting the synthesis filtered composite waveform; differencing the perceptually weighted synthesis filtered composite waveform from the perceptually weighted input waveform to form an output waveform; searching through the first plurality of codebooks and the adaptive codebook to minimize the errors in the output waveform; and decoding the output waveform using a second plurality of codebooks and at least one second adaptive codebook. - View Dependent Claims (2, 3)
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4. A system to encode and decode sound, comprising:
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an analyzer to compute linear prediction coefficients for a portion of an input waveform; a classifier for classifying the input waveform as one of a group comprising speech, speech and music, and music; a first plurality of codebooks, each having an output, where each codebook is associated with a frequency band; at least one first adaptive codebook having an output; a first coupler to couple the output of the first plurality of codebooks and the output of the at least one first adaptive codebook together to create a composite waveform; a synthesis filter for filtering the composite waveform; a first perceptual weighting filter for filtering the input waveform; a second perceptual weighting filter for filtering the synthesis filtered composite waveform; a signal combiner for differencing the perceptually weighted synthesis filtered composite waveform from the perceptually weighted input waveform to form an output waveform; selector means for searching through the first plurality of codebooks and the adaptive codebook to minimize the errors in the output waveform; and decoder means for decoding the output waveform, the decoder comprising a second plurality of codebooks and at least one second adaptive codebook. - View Dependent Claims (5, 6)
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7. A method for encoding an audio signal, comprising the steps of:
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generating a multiple band excitation codebook bank and at least one adaptive codebook; coupling the multiple band fixed excitation codebook bank and the at least one adaptive codebook for generating a composite excitation signal, providing a long-term and a short-term prediction signal; classifying as voice or music the composite excitation signal based on the long-term prediction signal and the short-term prediction signal; and adapting the classified composite excitation signal to a statistical character of the audio signal.
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Specification