EP0176243A2
Expired / Lapsed
EP
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Frequency domain speech coding
Assignee: British Telecommunications PLC
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Filing: 1985-08-23
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Granted: —
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Expires: 2005-08-23
Abstract
Abstract Adaptive bit allocation to the channels of a sub-band coder (or to the coefficients of a transform coder) is simplified by using a fixed set of numbers of bits, only the selection of those channels to which the available bits are assigned being varied.
Inventors
- 👤 Soo Ngee Koh
- 👤 Costas S. University Of Technology Xydeas
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 01:08
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/667; G; G10; G10L; G10L19/00; G10L19/02; G10L19/032; G10L19/0204
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
95 words
A coder for speech signals comprising separation means for receiving speech signals and generating series of values each series representing respective portions of the frequency spectrum of the input signal encoding means for digitally encoding each series, and bit allocation means for varying the number of bits used for encoding the respective series in dependence on the relative energy contents thereof, characterised in that the number of series to which any given number of bits is allocated is constant, only the selection of the series to which respective numbers of bits are allocated being varied.
Claim 2
Dependent Claim
95 words
A coder for speech signals comprising separation means for receiving speech signals and generating series of values each series representing respective portions of the frequency spectrum of the input signal encoding means for digitally encoding each series, and bit allocation means for varying the number of bits used for encoding the respective series in dependence on the relative energy contents thereof, characterised in that the number of series to which any given number of bits is allocated is constant, only the selection of the series to which respective numbers of bits are allocated being varied.
Claim 3
Dependent Claim
37 words
A coder according to claim 1 characterised in that it is a sub-band coder, the separation means comprising filter means each series being a series of samples of a respective sub frequency band of the signal spectrum.
Claim 4
Dependent Claim
28 words
A coder according to claim 1 comprising in that the separation means is a transform coder, each series being composed of the transform coefficients of a respective order.
Claim 5
Dependent Claim
54 words
A coder according to claim 1, 2 or 3 characterised in that it includes normalisation means for applying scaling factors to the respective series and the bit allocation means is arranged to effect bit allocation as a function of the scaling factors, whereby transmission of separate bit allocation information to a decoder is unnecessary.
Claim 6
Independent Claim
84 words
A method of coding a speech signal in which the signal is divided into separate channels representing respective portions of the frequency spectrum of the input signal, and the channels are each encoded using a variable number of bits dependent upon the relative energy contents of the channels, characterised in that the number of channels to each of which any given number of bits is allocated is constant, only the selection of the channels to which respective numbers of bits are allocated being varied.
Claim 7
Independent Claim
84 words
A method of coding a speech signal in which the signal is divided into separate channels representing respective portions of the frequency spectrum of the input signal, and the channels are each encoded using a variable number of bits dependent upon the relative energy contents of the channels, characterised in that the number of channels to each of which any given number of bits is allocated is constant, only the selection of the channels to which respective numbers of bits are allocated being varied.
Claim 8
Dependent Claim
15 words
A coder for speech signals substantially as herein described with reference to the accompanying drawings.
Claim 9
Dependent Claim
15 words
A coder for speech signals substantially as herein described with reference to the accompanying drawings.
Claim 10
Independent Claim
16 words
A method of coding speech signals substantially as herein described with reference to the accompanying drawings.
Claim 11
Independent Claim
16 words
A method of coding speech signals substantially as herein described with reference to the accompanying drawings.
References Cited (Backward Citations)
No citation records indexed.
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