US5909663A
Expired / Lapsed
US
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Speech decoding method and apparatus for selecting random noise codevectors as excitation signals for an unvoiced speech frame
Assignee: Sony Corp
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Filing: 1997-09-05
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Granted: 1999-06-01
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Expires: 2017-09-05
Abstract
Abstract If the same parameter is repeatedly used in an unvoiced frame inherently devoid of pitch, there is produced a pitch of the frame length period, thus producing an extraneous feeling. This can be prevented from occurring by evading repeated use of excitation vectors having the same waveform shape. To this end, when decoding an encoded speech signal obtained on waveform encoding an encoding-unit-based time-axis speech signal obtained on splitting an input speech signal in terms of a pre-set encoding unit on the time axis, input data is checked by CRC by a CRC and bad frame masking circuit 281, which processes a frame corrupted with an error with bad frame masking of repeatedly using parameters of a directly previous frame. If the error-corrupted frame is unvoiced, an unvoiced speech synthesis unit 220 adds the noise to an excitation vector from a noise codebook or randomly selects the excitation vector of the noise codebook.
Inventors
- 👤 Kazuyuki Iijima
- 👤 Masayuki Nishiguchi
- 👤 Jun Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:39
CPC Classifications
H; H03; H03M; H03M7/00; H03M7/30; G; G10; G10L; G10L19/00; G10L19/005
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
123 words
A speech decoding method for decoding an encoded speech signal produced by dividing an input speech signal on a time axis using a pre-set encoding unit and by waveform-encoding a resulting encoding-unit-based time-axis waveform signal, said method comprising: a waveform-decoding step for producing an encoding-unit-based time-axis waveform signal, wherein said time-axis waveform signal is an excitation signal for synthesis of an unvoiced speech signal; an error detecting step for detecting an error using an error checking code appended to said encoded speech signal; and an evading step for evading repeated use of a same waveform as a waveform used in said waveform-decoding step by using a waveform different from a directly preceding waveform when an error is detected in said error detecting step.
Claim 2
Dependent Claim
123 words
A speech decoding method for decoding an encoded speech signal produced by dividing an input speech signal on a time axis using a pre-set encoding unit and by waveform-encoding a resulting encoding-unit-based time-axis waveform signal, said method comprising: a waveform-decoding step for producing an encoding-unit-based time-axis waveform signal, wherein said time-axis waveform signal is an excitation signal for synthesis of an unvoiced speech signal; an error detecting step for detecting an error using an error checking code appended to said encoded speech signal; and an evading step for evading repeated use of a same waveform as a waveform used in said waveform-decoding step by using a waveform different from a directly preceding waveform when an error is detected in said error detecting step.
Claim 3
Dependent Claim
32 words
The speech decoding method as claimed in claim 1, wherein said encoded speech signal is obtained by vector quantization of said time-axis waveform signal by a closed-loop search employing an analysis-by-synthesis method.
Claim 4
Dependent Claim
30 words
The speech decoding method as claimed in claim 1, wherein noise components are added to said excitation signal in said evading step for evading repeated use of said same waveform.
Claim 5
Dependent Claim
30 words
The speech decoding method as claimed in claim 1, wherein noise components are substituted for said excitation signal in said evading step for evading repeated use of said same waveform.
Claim 6
Dependent Claim
48 words
The speech decoding method as claimed in claim 1, wherein said excitation signal is from a noise codebook for synthesis of said unvoiced sound, and said excitation signal is selected at random from said noise codebook in said evading step for evading repeated use of said same waveform.
Claim 7
Dependent Claim
33 words
The speech decoding method as claimed in claim 1, wherein said encoded speech signal is decoded in terms of an encoding unit having a duration longer than that of said pre-set encoding unit.
Claim 8
Dependent Claim
126 words
A speech decoding apparatus for decoding an encoded speech signal produced by dividing an input speech signal on a time axis using a pre-set encoding unit and by waveform-encoding a resulting encoding-unit-based time-axis waveform signal, said apparatus comprising: waveform-decoding means for waveform-decoding said encoded speech signal and for producing an encoding-unit-based time-axis waveform signal, wherein said time-axis waveform signal is an excitation signal for synthesis of an unvoiced speech signal; error detection means for detecting an error using an error checking code appended to said encoded speech signal; and evading means for evading repeated use of a same waveform as a waveform used by said waveform-decoding means by using a waveform different from a directly-preceding waveform when an error is detected by said error detection means.
Claim 9
Dependent Claim
126 words
A speech decoding apparatus for decoding an encoded speech signal produced by dividing an input speech signal on a time axis using a pre-set encoding unit and by waveform-encoding a resulting encoding-unit-based time-axis waveform signal, said apparatus comprising: waveform-decoding means for waveform-decoding said encoded speech signal and for producing an encoding-unit-based time-axis waveform signal, wherein said time-axis waveform signal is an excitation signal for synthesis of an unvoiced speech signal; error detection means for detecting an error using an error checking code appended to said encoded speech signal; and evading means for evading repeated use of a same waveform as a waveform used by said waveform-decoding means by using a waveform different from a directly-preceding waveform when an error is detected by said error detection means.
Claim 10
Dependent Claim
32 words
The speech decoding apparatus as claimed in claim 7, wherein said encoded speech signal is obtained by vector quantization of said time-axis waveform signal by a closed-loop search employing an analysis-by-synthesis method.
Claim 11
Dependent Claim
25 words
The speech decoding apparatus as claimed in claim 7, wherein said evading means includes noise addition means for adding noise components to said excitation signal.
Claim 12
Dependent Claim
23 words
The speech decoding apparatus as claimed in claim 7, wherein said evading means includes means for substituting noise components for said excitation signal.
Claim 13
Dependent Claim
33 words
The speech decoding apparatus as claimed in claim 7, wherein said encoded speech signal is decoded in terms of an encoding unit having a duration longer than that of said pre-set encoding unit.
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| 3.5 Years (Year 4) | 2002-05-31 | 2002-11-30 | 2003-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-05-31 | 2006-11-30 | 2007-06-01 | $3760.00 | Window Closed / Lapsed |
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