APPARATUS AND METHOD FOR IMPROVED CONCEALMENT OF THE ADAPTIVE CODEBOOK IN A CELP-LIKE CONCEALMENT EMPLOYING IMPROVED PULSE RESYNCHRONIZATION

• US 20160111094A1
• Filed: 12/21/2015
• Published: 04/21/2016
• Est. Priority Date: 06/21/2013
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Lecomte, Jeremie, Markovic, Goran, Dietz, Martin, Neugebauer, Bernhard, Schnabel, Michael
• Granted Patent: US 10,013,988 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/08 Determination or coding of the excitation function; Determination or coding of the long-term prediction parameters
• CPC Class Codes: G10L 19/107 Sparse pulse excitation, e.g. by using algebraic codebook
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 2019/0002 Codebook adaptations
• CPC Class Codes: G10L 2019/0008 Algebraic codebooks

Abstract

An apparatus for reconstructing a frame including a speech signal as a reconstructed frame is provided, the apparatus including a determination unit and a frame reconstructor being configured to reconstruct the reconstructed frame, such that the reconstructed frame completely or partially includes the first reconstructed pitch cycle, such that the reconstructed frame completely or partially includes a second reconstructed pitch cycle, and such that the number of samples of the first reconstructed pitch cycle differs from a number of samples of the second reconstructed pitch cycle.

Claims

1. An apparatus for reconstructing a frame comprising a speech signal as a reconstructed frame, said reconstructed frame being associated with at least one available frame, said at least one available frame being at least one of preceding frames of the reconstructed frame and at least one succeeding frame of the reconstructed frame, wherein the at least one available frame comprises at least one pitch cycle as at least one available pitch cycle, wherein the apparatus comprises:

a determination unit for determining a sample number difference indicating a difference between a number of samples of one of the at least one available pitch cycle and a number of samples of a first pitch cycle to be reconstructed, and

a frame reconstructor for reconstructing the reconstructed frame by reconstructing, depending on the sample number difference and depending on the samples of said one of the at least one available pitch cycle, the first pitch cycle to be reconstructed as a first reconstructed pitch cycle,

wherein the frame reconstructor is configured to reconstruct the reconstructed frame, such that the reconstructed frame comprises the first reconstructed pitch cycle, such that the reconstructed frame comprises a second reconstructed pitch cycle, and such that the number of samples of the first reconstructed pitch cycle differs from a number of samples of the second reconstructed pitch cycle,

wherein the frame reconstructor is adapted to generate an intermediate frame depending on said one of the at least one available pitch cycle,

wherein the frame reconstructor is adapted to generate the intermediate frame so that the intermediate frame comprises a first partial intermediate pitch cycle, at least one further intermediate pitch cycle, and a second partial intermediate pitch cycle,

wherein the first partial intermediate pitch cycle depends on at least one of the samples of said one of the at least one available pitch cycle, wherein each of the at least one further intermediate pitch cycle depends on all of the samples of said one of the at least one available pitch cycle, and wherein the second partial intermediate pitch cycle depends on at least one of the samples of said one of the at least one available pitch cycle,

wherein the determination unit is configured to determine a start portion difference number indicating how many samples are to be removed or added from the first partial intermediate pitch cycle, and wherein the frame reconstructor is configured to remove at least one first sample from the first partial intermediate pitch cycle, or is configured to add at least one first sample to the first partial intermediate pitch cycle depending on the start portion difference number,

wherein the determination unit is configured to determine for each of the further intermediate pitch cycles a pitch cycle difference number indicating how many samples are to be removed or added from said one of the further intermediate pitch cycles, and wherein the frame reconstructor is configured to remove at least one second sample from said one of the further intermediate pitch cycles, or is configured to add at least one second sample to said one of the further intermediate pitch cycles depending on said pitch cycle difference number, and

wherein the determination unit is configured to determine an end portion difference number indicating how many samples are to be removed or added from the second partial intermediate pitch cycle, and wherein the frame reconstructor is configured to remove at least one third sample from the second partial intermediate pitch cycle, or is configured to add at least one third sample to the second partial intermediate pitch cycle depending on the end portion difference number.

2. An apparatus according to claim 1,

wherein the determination unit is configured to determine a sample number difference for each of a plurality of pitch cycles to be reconstructed, such that the sample number difference of each of the pitch cycles indicates a difference between the number of samples of said one of the at least one available pitch cycle and a number of samples of said pitch cycle to be reconstructed, and

wherein the frame reconstructor is configured to reconstruct each pitch cycle of the plurality of pitch cycles to be reconstructed depending on the sample number difference of said pitch cycle to be reconstructed and depending on the samples of said one of the at least one available pitch cycle, to reconstruct the reconstructed frame.

3. An apparatus according to claim 1,

wherein the determination unit is configured to determine a position of at least one pulse of the speech signal of the frame to be reconstructed as reconstructed frame, and

wherein the frame reconstructor is configured to reconstruct the reconstructed frame depending on the position of the at least one pulse of the speech signal.

4. An apparatus according to claim 1,

wherein the determination unit is configured to determine an index k of a last pulse of the speech signal of the frame to be reconstructed as the reconstructed frame such that

5. An apparatus according to claim 1,

wherein the determination unit is configured to determine a rounded length T_r of said one of the at least one available pitch cycle based on formula:

T_r=└

T_p+0.5 ┘

wherein T_p indicates the length of said one of the at least one available pitch cycle,

wherein the apparatus is configured to reconstruct the frame to be reconstructed as the reconstructed frame depending on the rounded length T_r of said one of the at least one available pitch cycle.

6. An apparatus according to claim 1,

wherein the determination unit is configured to determine a parameter s by applying the formula:

7. An apparatus according to claim 1,

wherein the apparatus is configured to reconstruct the frame to be reconstructed as the reconstructed frame depending on the formula:

8. An apparatus according to claim 1,

wherein the frame reconstructor is adapted to generate the intermediate frame so that the intermediate frame comprises the first partial intermediate pitch cycle, more than one further intermediate pitch cycles as the at least one further intermediate pitch cycle, and the second partial intermediate pitch cycle,

wherein the apparatus is configured to calculate the number of samples A, to be removed from or added to each of the at least one further intermediate pitch cycle based on:

Δ

_i=|T_r−

T_ext|−

(k+1−

i)a,1≦

i≦

k

wherein T_r indicates a rounded length of said one of the at least one available pitch cycle,

wherein T_ext T_ext indicates a length of one of the pitch cycles to be reconstructed of the frame to be reconstructed as the reconstructed frame,

wherein k indicates an index of a last pulse of the speech signal of the frame to be reconstructed as the reconstructed frame,

wherein i is an integer, and

wherein a is a number indicating a delta of the samples to be added or removed between consecutive pitch cycles.

9. An apparatus according to claim 8,

wherein the apparatus is configured to determine the number a according to

10. An apparatus according to claim 9,

wherein the apparatus is configured to calculate the number of samples to be removed from or added to the first partial intermediate pitch cycle based on:

11. A method for reconstructing a frame comprising a speech signal as a reconstructed frame, said reconstructed frame being associated with at least one available frame, said at least one available frame being at least one of at least one preceding frame of the reconstructed frame and at least one succeeding frame of the reconstructed frame, wherein the at least one available frame comprises at least one pitch cycle as at least one available pitch cycle, wherein the method comprises:

determining a sample number difference indicating a difference between a number of samples of one of the at least one available pitch cycle and a number of samples of a first pitch cycle to be reconstructed, and

reconstructing the reconstructed frame by reconstructing, depending on the sample number difference and depending on the samples of said one of the at least one available pitch cycle, the first pitch cycle to be reconstructed as a first reconstructed pitch cycle,

wherein reconstructing the reconstructed frame is conducted, such that the reconstructed frame comprises the first reconstructed pitch cycle, such that the reconstructed frame comprises a second reconstructed pitch cycle, and such that the number of samples of the first reconstructed pitch cycle differs from a number of samples of the second reconstructed pitch cycle,

wherein the method further comprises generating an intermediate frame depending on said one of the at least one available pitch cycle,

wherein generating the intermediate frame is conducted so that the intermediate frame comprises a first partial intermediate pitch cycle, at least one further intermediate pitch cycle, and a second partial intermediate pitch cycle,

wherein the first partial intermediate pitch cycle depends on at least one of the samples of said one of the at least one available pitch cycle, wherein each of the at least one further intermediate pitch cycle depends on all of the samples of said one of the at least one available pitch cycle, and wherein the second partial intermediate pitch cycle depends on at least one of the samples of said one of the at least one available pitch cycle,

wherein the method further comprises determining a start portion difference number indicating how many samples are to be removed or added from the first partial intermediate pitch cycle, and wherein the method further comprises removing at least one first sample from the first partial intermediate pitch cycle, or is configured to add at least one first sample to the first partial intermediate pitch cycle depending on the start portion difference number,

wherein the method further comprises determining for each of the further intermediate pitch cycles a pitch cycle difference number indicating how many samples are to be removed or added from said one of the further intermediate pitch cycles, and wherein the method further comprises removing at least one second sample from said one of the further intermediate pitch cycles, or is configured to add at least one second sample to said one of the further intermediate pitch cycles depending on said pitch cycle difference number, and

wherein the method further comprises determining an end portion difference number indicating how many samples are to be removed or added from the second partial intermediate pitch cycle, and wherein the method further comprises removing at least one third sample from the second partial intermediate pitch cycle, or is configured to add at least one third sample to the second partial intermediate pitch cycle depending on the end portion difference number.

12. A computer program for implementing the method of claim 11 when being executed on a computer or signal processor.