Method and apparatus for variable length encoding of separated tone and noise characteristic components of an acoustic signal
First Claim
1. A signal encoding apparatus adapted for encoding an input signal, comprising:
- transforming means for transforming an input signal into a block of frequency components, each frequency component characterized by an energy distribution;
separating means for separating an output of the transforming means into a first signal consisting of tone characteristic components each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block and a second signal consisting of components other than the tone characteristic components;
first encoding means for encoding the first signal; and
second encoding means for encoding the second signal, the first encoding means including variable length encoding means for implementing variable length encoding to respective signal components of only the first signal.
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Abstract
A signal encoding apparatus for encoding an acoustic signal. This signal encoding apparatus includes a transform circuit for transforming an inputted acoustic signal into frequency components, a signal component separating circuit for separating an output of the transform circuit into tone characteristic components and noise characteristic components, a tone characteristic encoding circuit for encoding a signal of tone characteristic components, and a noise characteristic component encoding circuit for encoding a signal of noise characteristic components, wherein the tone characteristic component encoding circuit encodes respective signal components of the signal of tone characteristic components so that they respectively have different code lengths to thereby improve efficiency of encoding without degrading sound quality with respect to acoustic signal of tone characteristic.
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Citations
35 Claims
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1. A signal encoding apparatus adapted for encoding an input signal, comprising:
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transforming means for transforming an input signal into a block of frequency components, each frequency component characterized by an energy distribution; separating means for separating an output of the transforming means into a first signal consisting of tone characteristic components each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block and a second signal consisting of components other than the tone characteristic components; first encoding means for encoding the first signal; and second encoding means for encoding the second signal, the first encoding means including variable length encoding means for implementing variable length encoding to respective signal components of only the first signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A signal encoding apparatus adapted for encoding an input signal, comprising:
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transforming means for transforming an input signal into a block of frequency components; separating means for separating an output of the transforming means into a first signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block, and a second signal consisting of components other than the tone characteristic components; first encoding means for normalizing amplitude information of respective tone characteristic components of only the first signal by using normalization coefficients, and quantizing the normalized amplitude information to generate an encoded signal; and second encoding means for encoding the second signal, the first encoding means being operative to output, as the encoded signal, an encoded signal relating to frequency components except for a maximum frequency component of the respective tone characteristic components. - View Dependent Claims (9, 10, 11)
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12. A signal decoding apparatus adapted for decoding an encoded signal, comprising:
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first decoding means for decoding a first signal consisting of tone characteristic components caused to undergo variable length encoding, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in a block; second decoding means for decoding a second signal consisting of components other than tone characteristic components; and synthetic inverse transforming means for synthesizing respective signals to inversely transform them, or inversely transforming respective signals to synthesize them. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A signal decoding apparatus adapted for decoding an encoded signal, comprising:
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first decoding means for decoding a normalized and encoded first signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distributions of frequency components in a block; second decoding means for decoding a second signal consisting of components other than the tone characteristic components; and synthetic inverse transforming means for synthesizing respective signals to inversely transform them, or inversely transforming respective signals to synthesize them, the first decoding means being operative to reproduce a maximum frequency component of the tone characteristic component on the basis of transmitted normalization coefficient. - View Dependent Claims (20, 21, 22)
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23. A signal encoding method for encoding an input signal, comprising the steps of:
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transforming an input signal into a block of frequency components, each frequency component characterized by an energy distribution; separating the frequency components into a signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block, and a second signal consisting of components other than the tone characteristic components; implementing variable length encoding to only the first signal; and encoding the second signal. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A signal encoding method for encoding an input signal, comprising the steps of:
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transforming an input signal into a block of frequency components each frequency component characterized by an energy distribution; separating the frequency components of the transformed input signal into a first signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block, and a second signal consisting of components other than the tone characteristic components; normalizing amplitude information of respective tone characteristic components of the first signal by using normalization coefficients, and quantizing the normalized amplitude information to encode them; and encoding the second signal; the step of encoding the first signal includes a step of outputting, as the encoded signal, an encoded signal relating to frequency components except for a maximum frequency component of the respective tone characteristic components. - View Dependent Claims (30, 31)
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32. A signal decoding method for decoding an encoded signal, comprising the steps of:
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decoding a normalized and encoded first signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in a block; and decoding a second signal consisting of components other than the tone characteristic components; synthesizing respective signals to inversely transform them, or inversely transforming respective signals to synthesize them, thus to reproduce an original signal, the step of decoding the first signal including a step of reproducing a maximum frequency component of the tone characteristic components on the basis of transmitted normalization coefficients. - View Dependent Claims (33, 34)
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35. A signal encoding apparatus adapted for encoding an input signal, comprising:
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transforming means for transforming an input signal into a block of frequency components, each frequency component characterized by an energy distribution; separating means for separating an output of the transforming means into a first signal consisting of tone characteristic components, each tone characteristic component having a sharp energy distribution relative to energy distributions of frequency components in a local neighborhood of the tone characteristic component and to energy distribution of frequency components in the block, and a second signal consisting of components other than the tone characteristic components; first encoding means for encoding only the first signal and alternatively only the second signal, the first encoding means including variable length encoding means for implementing variable length encoding to respective signal components of the first signal and alternatively the second signal; and second encoding means for encoding the second signal when the first encoding means encodes the first signal and alternatively encoding the first signal when the first encoding means encodes the second signal.
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Specification