Encoding and decoding apparatus causing no deterioration of sound quality even when sine-wave signal is encoded
First Claim
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1. An encoding and decoding apparatus having an encoding section for encoding a digital input signal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, whereinthe encoding section comprises:
- a block length determining section which time-sharingly divides the input signal into blocks each having a specified block length according to a degree of change of the input signal;
a frequency band dividing section which divides a signal of each of the blocks into a plurality of frequency bands to generate, for each, a respective frequency band signal;
a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, and determines an amount of quantization bits to be allocated to each of the frequency bands based on a magnitude of the masking threshold value-to-noise ratio; and
a quantizing section which receives information representing the quantization bit amount from the bit allocating section, and quantizes the frequency band signalthe bit allocating section comprises means for adopting a varied psychoacoustic characteristic according to the block length by receiving information representing the block length from the block length determining section.
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Abstract
There is provided an encoding and decoding apparatus which can provide a high quality of reproduction of sound. There are provided an encoding section and a decoding section. A block length determining section of the encoding section time-sharingly divides an input signal into blocks having a block length corresponding to the degree of change of the input signal. A frequency band dividing section divides the signal of each block into a plurality of frequency bands. A bit allocating section obtains a masking threshold value-to-noise ratio of each frequency band from the magnitude of the power of each frequency band reflecting a psychoacoustic characteristic, and determines the number of quantization bits to be allocated to each frequency band based on the magnitude of the masking threshold value-to-noise ratio. A quantizing section generates a code string by quantizing the signal while allocating a specified amount of bits to each frequency band based on information from the bit allocating section. The bit allocating section receives information representing the block length from the block length determining section, and adopts a different psychoacoustic characteristic depending upon the block length.
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Citations
11 Claims
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1. An encoding and decoding apparatus having an encoding section for encoding a digital input signal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, wherein
the encoding section comprises: -
a block length determining section which time-sharingly divides the input signal into blocks each having a specified block length according to a degree of change of the input signal; a frequency band dividing section which divides a signal of each of the blocks into a plurality of frequency bands to generate, for each, a respective frequency band signal; a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, and determines an amount of quantization bits to be allocated to each of the frequency bands based on a magnitude of the masking threshold value-to-noise ratio; and a quantizing section which receives information representing the quantization bit amount from the bit allocating section, and quantizes the frequency band signal the bit allocating section comprises means for adopting a varied psychoacoustic characteristic according to the block length by receiving information representing the block length from the block length determining section.
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2. An encoding and decoding apparatus having
an encoding section for encoding a digital input signal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, wherein the encoding section comprises: -
a frequency band dividing section which divides the input signal into a plurality of frequency bands every specified time division unit to generate a frequency band signal; a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, determines a number of quantization bits to be allocated to each of the frequency bands based on a magnitude of the masking threshold value-to-noise, and determines respective maximum numbers of bits to be respectively allocated to the frequency bands by the time division unit; and a quantizing section which receives information representing the quantization bit number from the bit allocating section, and quantizes the frequency band signal. - View Dependent Claims (3, 4, 5, 6, 7)
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8. An encoding and decoding apparatus having
a encoding section for encoding a digital input sisal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, wherein the encoding section comprises: -
a frequency band dividing section which divides the input signal into a plurality of frequency bands every specified time division unit to generate a frequency band signal; a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, and determines a number of quantization bits to be allocated to each of the frequency bands, based on a magnitude of the masking threshold value-to-noise ratio; and a quantizing section which receives information representing the quantization bit number from the bit allocating section, and quantizes the frequency band signal, and wherein the bit allocating section includes an initial bit allocating part for deciding whether a ratio of a power of one frequency and to a power of all the frequency bands is not smaller than a specified ratio, and allocating at least a minimum number of quantization bits to the one frequency band having a power not smaller in ratio than the specified ratio, before allocating the quantization bits to each frequency band.
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9. An encoding and decoding apparatus having an encoding section for encoding a digital input signal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, wherein
the encoding section comprises: -
a frequency band dividing section which divides the input signal into a plurality of frequency bands every specified time division unit to generate a frequency band signal; a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, and determines a number of quantization bits to be allocated to each of the frequency bands, based on a magnitude of the masking threshold value-to-noise ratio; and a quantizing section which receives information representing the quantization bit number from the bit allocating section, and quantizes the frequency band signal, and wherein the bit allocating section comprises means for allocating to the frequency bands a number of bits obtained by subtracting a number of extra bits to be allocated to the predetermined frequency band from a total number of quantization bits allocatable to all the frequency bands, and subsequently adding to a number of bits allocated to the predetermined frequency band the number of extra bits to be allocated. - View Dependent Claims (10)
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11. An encoding and decoding apparatus having an encoding section for encoding a digital input signal composed of a musical sound, a vocal sound, or a combination of the sounds, and a decoding section for decoding a signal encoded by the encoding section, wherein
the encoding section comprises: -
a block length determining section which time-sharingly divides the input signal into blocks each having a specified block length according to a degree of change of the input signal; a frequency band dividing section which divides a signal of each of the blocks into a plurality of frequency bands to generate a frequency band signal; a bit allocating section which obtains a masking threshold value-to-noise ratio from a magnitude of a power of each of the frequency bands reflecting a psychoacoustic characteristic, and determines an amount of quantization bits to be allocated to each of the frequency bands based on a magnitude of the masking threshold value-to-noise ratio; and a quantizing section which receives information representing the quantization bit amount from the bit allocating section, and quantizes the frequency band signal, and wherein the bit allocating section consists of two means selected from the group consisting of;
means for adopting a varied psychoacoustic characteristic according to the block length by receiving information representing the block length from the block length determining section;
means for limiting a maximum amount of bits to be allocated to each of the frequency bands every frequency band;
means for deciding whether a ratio of a power of one frequency band to a power of all the frequency bands is not smaller than a specified ratio, and allocating at least a minimum amount of quantization bits to the one frequency band having a power not smaller in ratio than the specified ratio regardless of a magnitude of the masking threshold value-to-noise ratio; and
means for allocating a predetermined amount of extra bits to a predetermined frequency band.
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Specification
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Current AssigneeSharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
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Original AssigneeSharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
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InventorsMiyakawa, Harumitsu, Kawama, Shuichi
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Primary Examiner(s)Safourek, Benedict V.
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Application NumberUS08/344,166Time in Patent Office1,077 DaysField of Search395/2, 395/2.1, 395/2.14, 395/2.38, 395/2.39, 375/240, 375/241, 370/83, 370/118US Class Current704/229CPC Class CodesG10L 19/002 Dynamic bit allocation for ...G10L 19/0212 using orthogonal transforma...G10L 19/10 the excitation function bei...H04B 1/665 using psychoacoustic proper...
