System for predictive coding/decoding of a digital speech signal by embedded-code adaptive transform
First Claim
1. System for predictive coding of a digital signal as an embedded-code digital signal, coded by embedded-code adaptive transformation, in which the coded digital signal comprises a coded speech signal and, if appropriate, an auxiliary data signal inserted into the coded speech signal after coding said digital speech signal, said system comprising:
- a perceptual weighting filter driven by a short-term prediction loop delivering a perceptual signal;
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a long-term prediction circuit delivering an estimated perceptual signal P1n, said long-term prediction circuit forming a long-term prediction loop delivering, from said perceptual signal and from an estimated past excitation signal POn, a modelled perceptual excitation signal Pn ;
adaptive transform and quantization means for receiving said modelled perceptual excitation signal, and for generating said coded speech signal, said perceptual weighting filter including a filter, driven by a short-term prediction loop for providing short-term prediction of a speech signal to be coded, for producing a frequency distribution of quantization noise; and
means for subtracting said past excitation signal P0n, from said perceptual signal to deliver an updated modelled perceptual signal Pn,said long-term prediction circuit being formed, as a closed loop, from a dictionary updated by a modelled past excitation corresponding to the lowest throughput and delivering a waveform, and an estimated gain associated therewith, which make up the estimated perceptual signal,said adaptive transform and quantization means including an orthonormal transform module including an adaptive orthogonal transformation module and a module for progressive modelling by orthogonal vectors, said means of progressive modelling and said long-term prediction circuit making it possible to deliver indices representing the coded speech signal, said system further including means for inserting auxiliary data, coupled to a transmission channel.
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Abstract
A system for predictive coding of a digital speech signal with embedded codes used in any transmission system or for storing speech signals. The coded digital signal (Sn) is formed by a coded speech signal and, if appropriate, by auxiliary data. A perceptual weighting filter is formed by a filter for short-term prediction of the speech signal to be coded, in order to produce a frequency distribution of the quantization noise. A circuit makes it possible to perform the subtraction from the perceptual signal of the contribution of the past excitation signal P0n to deliver an updated perceptual signal Pn. A long-term prediction circuit is formed, as a closed loop, from a dictionary updated by the modelled page excitation r1 n for the lowest throughput and makes it possible to deliver an optimal waveform and an associated estimated gain which make up the estimated perceptual signal P1n. An orthonormal transform module includes an adaptive transform module and a module for progressive modelling by orthogonal vectors, thus making it possible to deliver indices representing the coded speech signal. A circuit makes it possible to insert auxiliary data by stealing bits from the coded speech signal. Decoding is performed through extraction of datasignal and transmission of indices representing coded speech signal which is modelled at the minimum throughput.
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Citations
12 Claims
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1. System for predictive coding of a digital signal as an embedded-code digital signal, coded by embedded-code adaptive transformation, in which the coded digital signal comprises a coded speech signal and, if appropriate, an auxiliary data signal inserted into the coded speech signal after coding said digital speech signal, said system comprising:
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a perceptual weighting filter driven by a short-term prediction loop delivering a perceptual signal;
;a long-term prediction circuit delivering an estimated perceptual signal P1n, said long-term prediction circuit forming a long-term prediction loop delivering, from said perceptual signal and from an estimated past excitation signal POn, a modelled perceptual excitation signal Pn ; adaptive transform and quantization means for receiving said modelled perceptual excitation signal, and for generating said coded speech signal, said perceptual weighting filter including a filter, driven by a short-term prediction loop for providing short-term prediction of a speech signal to be coded, for producing a frequency distribution of quantization noise; and means for subtracting said past excitation signal P0n, from said perceptual signal to deliver an updated modelled perceptual signal Pn, said long-term prediction circuit being formed, as a closed loop, from a dictionary updated by a modelled past excitation corresponding to the lowest throughput and delivering a waveform, and an estimated gain associated therewith, which make up the estimated perceptual signal, said adaptive transform and quantization means including an orthonormal transform module including an adaptive orthogonal transformation module and a module for progressive modelling by orthogonal vectors, said means of progressive modelling and said long-term prediction circuit making it possible to deliver indices representing the coded speech signal, said system further including means for inserting auxiliary data, coupled to a transmission channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. ε
- [ 1. L], and
θ
1 designates the gain value associated to said optimal vector;said parameters data including indices j(1) of the selected optimal vectors as well as number i(1) of the quantization ranges of their associated gain values, and transmission of said parameters data being carried out by overwriting the parts of a frame allocate to said indices and range numbers for 1 ε
[L1, L2 -1] and [L2, L], respectively, wherein L1 and L2 designate intermediate values between 1 and L, with 1≦
L1 ≦
L2 ≦
L. - View Dependent Claims (11)
- [ 1. L], and
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10. A system for predictive decoding by adaptive transform for a digital signal coded with embedded code in which the coded digital signal comprises a coded speech signal and, if appropriate, of an auxiliary data signal inserted into the coded speech signal after coding the latter, said coded speech signal being represented by parameters data modelling an estimated gain G, said estimated gain verifying the relation:
- ##EQU24## in which Ψ
kj(1) designates an optimal vector drawn from a stochastic dictionary of corresponding rank 1 with 1 ε
[1,L], andθ
1 designates the gain value associated to said optimal vector;said parameters data including indices j(1) of the selected optimal vectors as well as number i(1) of the quantization ranges of their associated gain values, said indices comprising received indices received through a transmission carried out by overwriting the parts of a frame allocated to said indices and range numbers for 1ε
[L1, L2 -1] and [L2, L], respectively, wherein L1 and L2 designate intermediate values between 1 and L, with 1≦
L1 ≦
L2 ≦
L, said system comprising;means for extracting auxiliary data from said data signal for an auxiliary use and for transmitting said received indices representing said coded speech signal to a modelling means;
said modelling means comprising means for modelling the speech signal from said received indices at a minimum throughput and for modelling the speech signal from said received indices at at least one throughput above said minimum throughput. - View Dependent Claims (12)
- ##EQU24## in which Ψ
Specification