EP0443548A2
Expired / Lapsed
EP
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Speech coder
Assignee: NEC Corp
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Filing: 1991-02-20
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Granted: —
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Expires: 2011-02-20
Abstract
Abstract A speech coder includes an LPC analyzer, a difference signal generating section, a first code book, a second code book, and a multiplexer. The LPC analyzer divides an input discrete speech signal into signal components in units of frames each having a predetermined time length, and obtains a spectrum parameter representing a spectrum envelope of the speech signal. The difference signal generating section obtains a difference signal by dividing the frame into subframes each having a predetermined time length, and predicting a pitch parameter representing a long-term correlation on the basis of a past sound source signal. The first code book stores a signal formed beforehand by learning based on the difference signal. The second code book stores a signal having predetermined characteristics or a signal formed beforehand by learning. The multiplexer represents a sound source signal of the speech signal by a linear combination of a signal selected from the first code book in accordance with each obtained difference signal and a signal selected from the second code book, and outputs the combination.
Inventors
- 👤 Kazunori C/O Nec Corporation Ozawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 10:13
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/08; G10L19/12; G10L2019/0001; G10L2019/0003; G10L2019/0004; G10L2019/0005; G10L2019/0011; G10L2019/0013; G10L2019/0014; G10L25/00; G10L25/03; G10L25/06; G10L25/18; G10L25/24
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
157 words
A speech coder characterized by comprising: means (130) for dividing an input discrete speech signal into signal components in units of frames each having a predetermined time length, and obtaining a spectrum parameter representing a spectrum envelope of the speech signal; means (150, 190, 205, 210) for obtaining a difference signal by dividing the frame into subframes each having a predetermined time length, and calculating a pitch parameter representing a long-term correlation on the basis of a past sound source signal; a first code book (235) for storing a signal formed beforehand by learning based on the difference signal; a second code book (275) for storing a signal having predetermined characteristics; and means (240) for representing a sound source signal of the speech signal by a linear combination of a signal selected from said first code book in accordance with each obtained difference signal and a signal selected from said second code book, and outputting the combination.
Claim 2
Dependent Claim
19 words
A coder according to claim 1, wherein said second code book (275) stores a signal formed beforehand by learning.
Claim 3
Dependent Claim
93 words
A coder according to claim 1 or 2, further comprising a third code book (320) for storing predetermined types of signal formed in advance by learning based on a spectrum parameter, means (310, 325) for selecting one optimal type of signal from said third code book, and obtaining a differential parameter between the spectrum parameter and the selected signal from the third code book, and means (330) for quantizing the differential parameter on the basis of a statistical distribution range obtained in advance by measuring the differential parameter, thereby representing the spectrum parameter.
Claim 4
Dependent Claim
70 words
A coder according to claim 1, 2, or 3, further comprising means (230, 270) for representing a sound source signal of the speech signal by a linear combination of a signal selected from said first code book and a signal selected from said second code book, the signals being selected while the pitch parameter and a gain of at least one of said first and second code books are adjusted.
Claim 5
Dependent Claim
53 words
A coder according to claim 1, 2, or 3, further comprising means (230, 270) for selecting the pitch parameter and signals from said first and second code books, subsequently adjusting gains of the selected signals, and representing a sound source signal of the speech signal by a linear combination of the selected signals.
Claim 6
Dependent Claim
174 words
A speech coder comprising: means (130) for dividing an input discrete speech signal into signal components in units of frames each having a predetermined time length, and obtaining a spectrum parameter representing a spectrum envelope of the speech signal; means (150, 210) for dividing the frame into subframes each having a predetermined time length, and obtaining a pitch parameter so as to approximate a signal reproduced on the basis of a past sound source signal to the speech signal; a first code book (235) for storing a signal formed by learning based on the speech signal; a second code book (275) for storing a signal having predetermined characteristics; means (291) for representing a sound source signal of the speech signal by a linear combination of signals respectively selected from said first and second code books; and means (286) for quantizing a gain of at least one of the pitch parameter and gains of said first and second code books by using a gain code book (287) formed in advance, and outputting the quantized gain.
Claim 7
Dependent Claim
18 words
A coder according to claim 6, wherein said second code book (275) stores a signal formed by learning.
Claim 8
Dependent Claim
164 words
A speech coder comprising: means (130) for dividing an input discrete speech signal into signal components in units of frames each having a predetermined time length, and obtaining a spectrum parameter representing a spectrum envelope of the speech signal; means (150, 210) for dividing the frame into subframes each having a predetermined time length, and obtaining a delay amount of a pitch parameter so as to approximate a signal reproduced on the basis of a past sound source signal to the speech signal; means (225) for quantizing a gain of the pitch parameter by using a fourth code book formed in advance; a first code book (235) for storing a signal formed by learning based on the speech signal; a second code book (275) for storing a signal having predetermined characteristics; and means (260) for representing a sound source signal of the speech signal by a linear combination of signals respectively selected from said first and second code books, and outputting the linear combination.
Claim 9
Dependent Claim
18 words
A coder according to claim 8, wherein said second code book (275) stores a signal formed by learning.
References Cited (Backward Citations)
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