EP0590155A1
Expired / Lapsed
EP
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High-efficiency encoding method
Assignee: Sony Corp
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Filing: 1993-03-18
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Granted: —
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Expires: 2013-03-18
Abstract
Abstract A high-efficiency method for encoding data on the frequency axis obtained by dividing an input audio signal in a block unit and converting it to the frequency axis, wherein a band B VH having the highest center frequency among V (voiced) bands is sought when the number of change point of discrimination data of V (voiced sound)/UV (unvoiced sound) of all the bands on the on-frequency-axis data is judged greater than 1, the number N V of the V bands up to the band B VH is determined, whether or not their proportion is greater than a predetermined threshold value N th is judged, and one V/UV division position is determined. In this way, the V/UV judgement data for each band is converted to the data of one division position inside all the bands, so that the data quantity and the bit rate can be reduced. The quantity of computation of the code book search is reduced by using two-stage hierarchical vector quantitization when the on-frequency-axis data is quantitized, and the memory capacity of the code book is reduced.
Inventors
- 👤 Masayuki Sony Corporation Nishiguchi
- 👤 Jun Sony Corporation Matsumoto
- 👤 Shinobu Sony Corporation Ono
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 23:35
CPC Classifications
G; G10; G10L; G10L25/00; G10L25/90; G10L19/00; G10L19/02; G10L19/0212; G10L19/032; G10L19/038; G10L19/04; G10L19/08; G10L19/12; G10L19/16; G10L19/18; G10L25/93; G10L19/10; G10L2019/0001; G10L2019/0004; G10L2019/0005; G10L2025/937; G10L25/27
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
108 words
A high efficiency encoding method comprising the steps of: finding data on frequency axis by dividing an input audio signal on block-by-block basis and by converting the signal onto the frequency axis; dividing the data on the frequency axis into plural bands; deciding, for each of the divided bands, whether the band is voiced or unvoiced; detecting a band with the highest frequency among voiced bands; and finding information on a boundary point for demarcation between a voiced sound region and an unvoiced sound region on the frequency axis in accordance with the number of bands from a band on a low frequency side to the detected band.
Claim 2
Dependent Claim
66 words
The high efficiency encoding method as claimed in claim 1, wherein a position of the detected band is the boundary point between the voiced sound region and the unvoiced sound region when proportion of the number of voiced bands and the number of unvoiced bands from the band on the low frequency side to the detected band is equal to or higher than a predetermined threshold.
Claim 3
Dependent Claim
139 words
A high efficiency encoding method comprising the steps of: finding data on frequency axis as an M-dimensional vector on the basis of data obtained by dividing an input audio signal on block-by-block basis and by converting the signal onto the frequency axis; lowering the dimension to an S dimension, where S < M, by dividing the data on the frequency axis of the M-dimensional vector into plural groups and by finding a representative value for each group; processing data of the S-dimensional vector with first vector quantization; finding a corresponding S-dimensional code vector by inversely quantizing output data of the first vector quantization; expanding the S-dimensional code vector to the original M-dimensional vector; processing, with second vector quantization, data expressing a relation between the expanded M-dimensional vector and the data on the frequency axis of the original M-dimensional vector.
Claim 4
Dependent Claim
37 words
The high efficiency encoding method as claimed in claim 3, wherein data converted onto the frequency axis on the block-by-block basis and non-linearly compressed is used as the data on the frequency axis of the M-dimensional vector.
Claim 5
Dependent Claim
55 words
A high efficiency encoding method comprising the steps of: finding data on frequency axis as an M-dimensional vector by non-linearly compressing data obtained by dividing an input audio signal on block-by-block basis and converting the signal onto the frequency axis; and processing the data on the frequency axis of the M-dimensional vector with vector quantizaiton.
Claim 6
Dependent Claim
36 words
The high efficiency encoding method as claimed in claim 3, 4 or 5, wherein an inter-block difference of data to be vector-quantized is taken, and wherein data of the inter-block difference is processed with vector quantization.
Claim 7
Dependent Claim
54 words
A high efficiency encoding method comprising the steps of: finding inter-block difference data as an M-dimensional vector by taking an inter-block difference of data obtained by dividing an input audio signal on block-by-block basis and converting the signal onto frequency axis; and processing the inter-block difference data of the M-dimensional vector with vector quantization.
Claim 8
Dependent Claim
145 words
A high efficiency encoding method comprising the steps of: finding data on frequency axis as an M-dimensional vector by converting, into a dB region, spectral amplitude obtained by dividing an input voice signal on block-by-block basis and converting the signal onto the frequency axis; lowering the dimension to an S dimension, where S < M, by dividing the data on the frequency axis of the M-dimensional data into plural groups and finding an average value for each group; processing data of the average value of the S-dimensional vector with first vector quantization; finding a corresponding S-dimensional code vector by inversely quantizing output data of the first vector quantization; expanding the S-dimensional code vector to the original M-dimensional vector; and processing, with second vector quantization, data of a difference between the expanded M-dimensional vector and the data on the frequency axis of the original M-dimensional vector.
Claim 9
Dependent Claim
94 words
The high efficiency encoding method as claimed in claim 1 or 3, having a step of pitch extraction for taking out a waveform of the input audio signal on the block-by-block basis and for extracting a pitch on the basis of a center-clipped output signal, said pitch extraction comprising the steps of: dividing the block into plural sub-blocks and finding a level for clipping for each of the sub-blocks; and changing a clipping level in the block on the basis of the level for clipping found for each sub-block in center-clipping the input signal.
Claim 10
Dependent Claim
46 words
The high efficiency encoding method having the step of pitch extraction as claimed in claim 9, wherein the clipping level in center-clipping is changed in the block when a change of a peak level between adjacent sub-blocks among the plural sub-blocks in the block is large.
Claim 11
Dependent Claim
101 words
The high efficiency encoding method as claimed in claim 1 or 3, having a step of pitch extraction comprising: taking out the input audio signal on frame-by-frame basis with a block proceeding in a direction of time axis as a unit; detecting plural peaks from auto-correlation data of a current frame; finding a peak in a pitch range satisfying a predetermined relation with a pitch found in a frame other than the current frame, among the detected plural peaks of the current frame; and deciding a pitch of the current frame on the basis of a position of the found peak.
Claim 12
Dependent Claim
26 words
The high efficiency encoding method as claimed in claim 11, wherein all peaks are detected from the auto-correlation data of the current frame, in peak detection.
Claim 13
Dependent Claim
132 words
The high efficiency encoding method as claimed in claim 3 or 5, having a step of pitch extraction comprising: taking out an input audio signal on frame-by-frame basis with a block proceeding in a direction of time axis as a unit; detecting plural peaks from auto-correlation data of a current frame; and deciding a pitch of the current frame by a position of a maximum peak among the detected plural peaks of the current frame when the maximum peak is equal to or larger than a predetermined threshold, and deciding the pitch of the current frame by a position of a peak in a pitch range satisfying a predetermined relation with a pitch found in a frame other than the current frame when the maximum peak is smaller than the predetermined threshold.
Claim 14
Dependent Claim
86 words
The high efficiency encoding method as claimed in claim 1 or 3, for finding a spectral envelope of the input audio signal, dividing the spectral envelope into plural bands and performing quantization in accordance with power for each band, wherein a pitch of the input audio signal is detected, for dividing the spectral envelope with a bandwidth according to a detected pitch when the pitch is securely detected, and for dividing the spectral envelope with a predetermined narrower bandwidth when the pitch is not detected securely.
Claim 15
Dependent Claim
34 words
The high efficiency encoding method as claimed in claim 14, wherein all bands of the spectral envelope are unvoiced when no pitch is detected in detecting the pitch of the input signal audio signal.
Claim 16
Dependent Claim
68 words
The high efficiency encoding method as claimed in claim 1 or 3, comprising the steps of: non-linearly compressing data having a variable number of parameter data expressing waveform data or waveform in the block; and converting non-linearly compressed data of the variable number into a fixed number of data for comparing the variable number of non-linearly compressed data and the fixed number of reference data for each block.
Claim 17
Dependent Claim
56 words
The high efficiency encoding method as claimed in claim 16, wherein after dummy data such as to interpolate a value from the last data in the block to the first data in the block is added to the variable number of non-linearly compressed data, band limiting type oversampling is carried out on the non-linearly compressed data.
Claim 18
Dependent Claim
97 words
A high efficiency encoding method comprising the steps of: finding data on frequency axis as an M-dimensional vector on the basis of data obtained by dividing an input audio signal on block-by-block basis and converting the signal onto the frequency axis; and performing quantization, by using a vector quantizer having plural codebooks according to a state of the audio signal for processing the data on the frequency axis of the M-dimensional vector with vector quantization, and by changing over the plural codebooks in accordance with a parameter indicating characteristics of each block of the input audio signal.
Claim 19
Dependent Claim
61 words
The high efficiency encoding method as claimed in claim 18, wherein a voice signal is used as the audio signal and wherein plural codebooks according to whether the voice signal is voiced or unvoiced are used as the codebooks, while a parameter indicating whether the input voice signal for each block is voiced or unvoiced is used as the characteristics parameter.
Claim 20
Dependent Claim
59 words
The high efficiency encoding method as claimed in claim 3, having a step of quantization by using a second vector quantizer having plural codebooks according to a state of the audio signal for performing second vector quantization, and by changing over the plural codebooks in accordance with a parameter indicating characteristics for each block of the input audio signal.
Claim 21
Dependent Claim
78 words
The high efficiency encoding method as claimed in claim 1 or 3, wherein in searching a codebook consisting of plural code vectors using, as vectors, data obtained by converting the input signal onto frequency axis and in vector quantization for outputting an index of a searched code vector, a distance between code vectors in the codebook and a hamming distance at the time of expressing the index in a binary manner are coincident with each other in size.
Claim 22
Dependent Claim
87 words
The high efficiency encoding method as claimed in claim 1 or 3, wherein in searching a codebook consisting of plural code vectors using, as vectors, data obtained by converting the input signal onto frequency axis and in vector quantization for outputting an index of a searched code vector, part of bits of binary data indicating the index are protected with a error correction code, while a hamming distance of remaining bits and a distance between code vectors in the codebook are coincident with each other in size.
Claim 23
Dependent Claim
37 words
The high efficiency encoding method as claimed in claim 21 or 22, wherein a distance found by weighing due to a weighted matrix used for defining distortion measure is used as the distance between the code vectors.
Claim 24
Dependent Claim
132 words
A voice analysis-synthesis method comprising the steps of: dividing an input voice signal on block-by-block basis and finding pitch data in the block; converting the voice signal on the block-by-block basis onto frequency axis and finding data on the frequency axis; dividing the data on the frequency axis into plural bands on the basis of the pitch data; finding power information for each of the divided bands and voiced/unvoiced decision information; transmitting the pitch data, the power information for each band and the voiced/unvoiced decision information found in foregoing processes; predicting a block terminal edge phase on the basis of the pitch data for each block obtained by transmission and a block initial phase; and modifying the predicted terminal edge phase, using a noise having diffusion according to each of the bands.
Claim 25
Dependent Claim
16 words
The voice analysis-synthesis method as claimed in claim 24, wherein the noise is a Gaussian noise.
References Cited (Backward Citations)
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