Patent EP0267344A1 successfully refreshed from Google Patents.
EP0267344A1
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EP
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Process for the multi-rate encoding of signals, and device for carrying out said process
Assignee: International Business Machines Corp
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Filing: 1986-10-30
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Granted: —
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Expires: 2006-10-30
Abstract
Abstract A process for multirate subband encoding voice signals. At least a portion of the original signal bandwidth is plit into p sub-bands the contents of which is to be coded using dynamic allocation of quantizing levels throughout the sub-bands. Let's assume the signal is to be coded for a set of coding rates R(1) <R(2)<..<R(k)...<E(K). First the number of quantizing levels 1(i;R(1)) for the lowest rate is determined. Then the levsl for 1(i;R(k)), k=2,...,p are determined using: Then the sub-band samples S(i,j) are quantized according to 1(i; R(K). And, finally the obtained quantized sub-band samples are embedded into a multirate frame.
Inventors
- 👤 Michèle Rosso
- 👤 Claude Galand
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 15:23
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66; H04B1/667
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
208 words
A process for digitally block encoding a signal at a predetermined set of rates R(1) < R(2) <...< R(K) and for embedding the encoded signal into a multirate frame, including K sections numbered 1, 2, ... K, said encoding involving splitting the signal bandwidth into p sub-bands to derive therefrom sub band signal samples S(i,j) where i=1,..., p is the sub band index and j=1,...,N the sample index, within a block of N samples, requantizing the S(i,j)'s through a block quantizer the quantizing levels of which are optimally and dynamically adjusted to the relative sub band energy contents E(i); and multiplexing the requantized sub band samples into said multirate frame, said process being characterized in that it includes : - computing the number of levels 1(i, R(1)) for the lowest rate R(1); - deriving the number of levels 1(i; R(k)) for the subsequent rates using : for k=2,...,K i=1,...,p - quantizing the sub-band samples S(i,j) with the quantizer step adjusted to the number of levels computed for the highest rate R(K); - multiplexing the coded sub-band samples S(i,j) into a multirate frame including K sections, wherein SR(k) for k=1,...,K contains the sample bits to be added to samples quantized at rate R(k-1) for obtaining samples quantized at R(k).
Claim 2
Dependent Claim
208 words
A process for digitally block encoding a signal at a predetermined set of rates R(1) < R(2) <...< R(K) and for embedding the encoded signal into a multirate frame, including K sections numbered 1, 2, ... K, said encoding involving splitting the signal bandwidth into p sub-bands to derive therefrom sub band signal samples S(i,j) where i=1,..., p is the sub band index and j=1,...,N the sample index, within a block of N samples, requantizing the S(i,j)'s through a block quantizer the quantizing levels of which are optimally and dynamically adjusted to the relative sub band energy contents E(i); and multiplexing the requantized sub band samples into said multirate frame, said process being characterized in that it includes : - computing the number of levels 1(i, R(1)) for the lowest rate R(1); - deriving the number of levels 1(i; R(k)) for the subsequent rates using : for k=2,...,K i=1,...,p - quantizing the sub-band samples S(i,j) with the quantizer step adjusted to the number of levels computed for the highest rate R(K); - multiplexing the coded sub-band samples S(i,j) into a multirate frame including K sections, wherein SR(k) for k=1,...,K contains the sample bits to be added to samples quantized at rate R(k-1) for obtaining samples quantized at R(k).
Claim 3
Dependent Claim
45 words
A process according to claim 1 wherein the bit rate r(k) available for a quantizing of sub-band samples for rate R(k) is r(k)=R(k)=R(O), with R(O) being the bit rate to be assigned for overhead encoding purposes and inserted into section SR(1) of said multirate frame.
Claim 4
Dependent Claim
46 words
A process according to any one of claims 1 or 2 wherein said block encoding is performed using BCPCM techniques providing sub band characteristic terms C(i) to be used as parameters representative of the sub-bands energy contents to be inserted into the multirate frame overhead section.
Claim 5
Dependent Claim
15 words
A process according to claim 3 wherein said number of levels 1(i;R(1)) is derived from
Claim 6
Dependent Claim
20 words
A process according to claim 4 wherein the number of levels 1(i;R(1)) is rounded off to integer value L(i;R(1)) with
Claim 7
Dependent Claim
46 words
A process for encoding a voice signal using predictive encoding techniques providing a low frequency bandwidth signal to be processed according to claim 5 and parameters representative of the high frequency bandwidth energy contents said parameters being to be inserted into said overhead multirate frame section.
Claim 8
Dependent Claim
144 words
A process according to claim 5 or 6 further characterized in that said L(i;R(1)) computing are performed optimally using the following operations: a computing the optimal decimal values for 1(i;R(1)) b setting to a predetermined value N1 any 1(i;R(1)) smaller or equal to N1, and setting to a predetermined value N2 any 1(i;R(1)) greater than N2; and discarding the 1(i,R(1)) set sub-bands, from the following operations; c scanning the sub bands to locate the highest i th sub band carrying the lowest energy; d allocating an integer value L(i,R(1)) to the located sub band; e setting either to N1 or to N2 the allocated L(i,R(1)) based on said L(i,R(1)) either being smaller to N1 or being strictly greater than N2; f testing for locating the remaining non L(i,R(1)) set sub bands ating the operations starting from step "c" for said non set sub bands.
Claim 9
Dependent Claim
18 words
A process according to claim 7 wherein said integer values L(i;R(k)) are derived from L(i.R(1)), for k=2,...,K, using:
Claim 10
Dependent Claim
39 words
A process according to claim 8 for processing bit rates differing from each other by a multiple of the number p of sub bands and wherein L(i;R(k)) is derived by simply adding an integer number of bits to L(i;R(k-1).
Claim 11
Dependent Claim
18 words
A process according to claim 8 wherein L(i;R(k)) is derived from L(i;R(k-1) using : L(i;R(k))=L(i;R(k-1)).2 b(k) with b(k)=(R(k)-R(k-1))/p
Claim 12
Dependent Claim
166 words
A process according to any one of claims 5 through 10 characterized in that said sub band samples S(i,j) quantizing operations involve: - setting a quantizer step size QK(i) for the ith sub band to: QK(i)=2.C(i)/L(i;R(K)) i=1...,p - quantizing each sample to a new S K (i,j) value with: S K (i,j)=Int(S(i,j)/QK(i) for i=1,...,p and j=1,...,N where Int(A) denotes the integer part of A; - rate reducing the quantized SK(i,j) samples to sequentially derive therefrom data S k-1 (i,j) for k=K-1,..,1 and T k for k=K,...,2 using S k-1 (i,j) =Int(S k (i,j)/DELT(i;k)) if L(i;R(k-1)) is even or S k-1 (i,j) = Int(.5+S k (i,j)/DELT(i;k)) if L(i;R(k-1)) is odd and T k (i,j) = S k (i,j) - S (k-1) (i,j) . DELT(i,k) with DELT (i;k) = 2 to derive therefrom data S1(i,j) and T₂ (i,j),.....,TK(i,j); - packing the derived data into a macro-sample frame made to include the S1(i,j) for the p sub-bands into a first section SR1, and the T2(i,j),..., TK(i,j) into subsequent sections.
Claim 13
Dependent Claim
40 words
A process according to claim 11, wherein the macro sample SR1 section packing includes: - packing the S1(i,j) for i=1,...p into r(1) - bit words MS (j), according to : - multiplexing the N words MS(j) into same section SR1.
Claim 14
Dependent Claim
175 words
A sub-band coding system for digitally BCPCM encoding a speech signal S(n) at a predetermined rate R(K) selected among a set of rates R(1)<R(2)<...<R(K), said system including a QMF filter bank splitting at least a portion of the speech bandwidth into p sub bands and providing S(i,j) signal samples, i=1,2,..,p and j being the sample index within a BCPCM block; means for deriving C(i) characteristics terms therefrom; level means connected to said filter bank to derive number of quantizing levels by using said C(i)'s for the lowest rate R(1) and derive therefrom the levels for the other rates R(2),...,R(K); quantizing means connected to said level means and to said bank of filters to requantize said S(i,j) samples based on the number of quantizing levels for the highest route R(K); said system being characterized in that it includes means for multiplexing said quantized S(i,j) and said C(i) into said multirate frame, said multirate frame including a section for inserting therein the C(i)'s and sections for inserting the requantized S(i,j) bits for each one of said rates.
Claim 15
Dependent Claim
175 words
A sub-band coding system for digitally BCPCM encoding a speech signal S(n) at a predetermined rate R(K) selected among a set of rates R(1)<R(2)<...<R(K), said system including a QMF filter bank splitting at least a portion of the speech bandwidth into p sub bands and providing S(i,j) signal samples, i=1,2,..,p and j being the sample index within a BCPCM block; means for deriving C(i) characteristics terms therefrom; level means connected to said filter bank to derive number of quantizing levels by using said C(i)'s for the lowest rate R(1) and derive therefrom the levels for the other rates R(2),...,R(K); quantizing means connected to said level means and to said bank of filters to requantize said S(i,j) samples based on the number of quantizing levels for the highest route R(K); said system being characterized in that it includes means for multiplexing said quantized S(i,j) and said C(i) into said multirate frame, said multirate frame including a section for inserting therein the C(i)'s and sections for inserting the requantized S(i,j) bits for each one of said rates.
Claim 16
Dependent Claim
102 words
A multiport speech encoding system for concentrating encoded speech onto a wide band link, said multiport systems including: - for each port a sub-band coder according to claim 13 for coding the input speech S(n) by implementing the process of any one of claims 1 through 12; - a port activity controller connected to the individual port coders for measuring the relative ports activity and for adjusting each port multirate frame length by truncating the frame by dropping, as required, sections of each individual port multirate frame; and, - multiplexing means for multiplexing the adjusted port frames over said wide band link.
References Cited (Backward Citations)
EP0085820A1
Cited
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