Method and a device for source coding
View Patent ↗A method and a device for source coding with a time advanced excitation signal. During an encoding process, a source data signal is first divided into consecutive blocks, then a first set of parameters related to a filter describing properties of a first block covering a first time period is extracted, followed by the extraction of a second set of parameters related to an excitation signal for said filter, where said second set of parameters is determined from and describing properties of both the first block and a second block following the first block within a second time period starting later than said first time period and extending outside said first time period.
1. A coding method comprising:
extracting a first set of parameters related to a filter describing properties of a first block covering a first time period,
extracting a second set of parameters related to a excitation signal for said filter, where said second set of parameters is determined from and describing properties of both the first block and a second block following the first block within a second time period starting later than said first time period and extending outside said first time period; and
extracting at least one parameter related to said excitation signal on the basis of said second set of parameters relating to said first and second blocks, and of previously extracted and at least partially stored second set of parameters relating to a block preceding said first block and said first block.
2. The method of claim 1 , further comprising storing at least the part of said second set of parameters or an indication thereof which corresponds to said second block in order, to use said stored parameters for extracting at least one parameter of said second block following said first block.
3. The method of claim 1 , wherein said at least one parameter is substantially a gain parameter.
4. The method of claim 1 , wherein said first set of parameters substantially indicates a number of LPC (Linear Predictive Coding) parameters.
5. The method of claim 1 , wherein said second set of parameters substantially indicates a certain excitation vector in an excitation codebook comprising a plurality of vectors.
6. The method of claim 1 , wherein the starting point of said second time period is varied within said first time period.
7. The method of claim 1 , wherein at least said second set of parameters is extracted by utilizing substantially an analysis-by-synthesis loop.
8. The method of claim 1 , wherein said synthesis filter includes at least one of the following: LPC (Linear Prediction Coding) synthesis filter and LTP (Long-Term Prediction) synthesis filter.
9. The method of claim 1 , wherein said source data is substantially speech.
10. The method of claim 1 , wherein said first set of parameters is utilized in extracting said second set of parameters.
11. A method for decoding encoded data signal divided into consecutive blocks having the steps of
obtaining a first set of parameters for constructing a synthesis filter, said first set of parameters describing properties of a first block covering a first time period,
obtaining a second set of parameters for constructing an excitation signal for said synthesis filter, said second set of parameters describing properties of both the first block and a second block following the first block within a second time period starting later than said first time period and extending outside said first time period,
obtaining at least part of a previous second set of parameters for constructing an excitation signal for said synthesis filter, said previous second set of parameters describing properties of said first block during at least the time period between the beginning of said first time period and the beginning of said second time period,
combining the contribution of said previous second set of parameters and said second set of parameters for said excitation signal within said first time period,
constructing an excitation signal of said first block for said synthesis filter by utilizing said combination, and
filtering said constructed excitation signal through said synthesis filter.
12. The method of claim 11 , wherein said first set of parameters substantially indicates a number of LPC (Linear Predictive Coding) parameters.
13. The method of claim 11 , wherein said second set of parameters substantially indicates a certain excitation codebook vector in an excitation codebook comprising a plurality of vectors.
14. The method of claim 11 , further having the step of storing at least the part of said second set of parameters or an indication thereof which corresponds to said second block in order to use said stored parameters for creating the excitation signal of said second block.
15. An encoding device comprising:
a first analysis module configured to extract a first set of parameters corresponding to a first block of a source signal, wherein the first block covers a first time period; and
a second analysis module configured to extract a second set of parameters related to an excitation signal, wherein the second set of parameters corresponds to the first block and a second block of the source signal, and wherein the second block covers a second time period commencing after a start of the first time period and ending after an end of the first time period, wherein at least one parameter related to said excitation signal on the basis of said second set of parameters is extracted; and
a third analysis module configured to extract at least one parameter relating to said excitation signal on the basis of said second set of parameters related to said first and second blocks, and of previously extracted and at least partially stored second set of parameters relating to a block preceding said first block and said first block.
16. The encoding device of claim 15 , wherein said first set of parameters is received from an external entity.
17. The encoding device of claim 15 , wherein said first set of parameters is extracted by utilizing said source data.
18. The encoding device of claim 15 , further comprising a memory configured to store at least the part of said second set of parameters or an indication thereof corresponding to said second block in order to use said stored parameters for extracting at least one parameter of said second block following said first block.
19. The encoding device of claim 15 , further comprising a processing unit configured to vary the starting point of said second time period within said first time period.
20. The encoding device of claim 15 , wherein said second set of parameters is extracted by utilizing substantially an analysis-by-synthesis loop.
21. The encoding device of claim or 15 , wherein said first set of parameters is utilized in extracting said second set of parameters.
22. An electronic device for decoding source data divided into consecutive blocks, said device comprising processing means and memory means for processing and storing instructions and data, and data transfer means for accessing data, said device arranged to obtain
a first set of parameters for constructing a synthesis filter, said first set of parameters describing properties of a first block covering a first time period,
a second set of parameters for constructing an excitation signal for said synthesis filter, said second set of parameters describing properties of both the first block and a second block following the first block within a second time period starting later than said first time period and extending outside said first time period,
at least part of a previous second set of parameters for constructing an excitation signal for said synthesis filter, said previous second set of parameters describing properties of said first block during at least the time period between the beginning of said first time period and the beginning of said second time period, said device further arranged to combine the contribution of said previous second set of parameters and said second set of parameters for said excitation signal within said first time period,
to construct an excitation signal of said first block for said synthesis filter by utilizing said combination, and
to filter said constructed excitation signal through said synthesis filter.
23. The device of claim 22 that is substantially a mobile terminal, a network element, a data storage device, an audio playback device or a dictating machine.
24. The device of claim 22 that is substantially a decoder module or an encoder-decoder module.
25. An article of manufacture including a computer readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
extracting a first set of parameters at a first analysis module, wherein the first set of parameters corresponds to a first block of a source signal covering a first time period; and
extracting a second set of parameters related to an excitation signal at a second analysis module, wherein the second set of parameters corresponds to the first block and a second block of the source signal, and wherein the second block covers a second time period commencing after a start of the first time period and ending after an end of the first time period, wherein at least one parameter related to said excitation signal on the basis of said second set of parameters is extracted.
26. An article of manufacture including a computer readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
constructing a synthesis filter using a first set of parameters describing properties of a first block covering a first time period,
constructing an excitation signal for said synthesis filter using a second set of parameters describing properties of both the first block and a second block following the first block within a second time period starting later than said first time period and extending outside said first time period,
constructing an excitation signal for said synthesis filter using at least part of a previous second set of parameters describing properties of said first block during at least the time period between the beginning of said first time period and the beginning of said second time period,
combining the contribution of said previous second set of parameters and said second set of parameters for said excitation signal within said first time period,
constructing an excitation signal of said first block for said synthesis filter by utilizing said combination, and
filtering said constructed excitation signal through said synthesis filter.