Apparatus, methods and articles incorporating a fast algebraic codebook search technique
First Claim
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1. A method comprising conducting a random excitation codebook search in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec, wherein the random excitation codebook search in the ACELP codec is conducted by grouping pulse positions based on relative importance of pulse positions.
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Abstract
An efficient method for codebook search, employed in speech coding, uses an optimal pulse-position grouping and a split track arrangement, based on a likelihood estimator. Also disclosed are codecs, mobile voice communication devices, telecommunications equipment and telecommunications methods.
45 Citations
34 Claims
- 1. A method comprising conducting a random excitation codebook search in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec, wherein the random excitation codebook search in the ACELP codec is conducted by grouping pulse positions based on relative importance of pulse positions.
- 8. A method comprising grouping pulse positions for the purpose of conducting a random excitation codebook search in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec, wherein the pulse positions are grouped in a plurality of groups of number A and the pulse code combinations in a group is less than the number of pulse code combinations in a group if the pulse positions are grouped in a plurality of groups of number G wherein A is greater than G, and further wherein the pulses are grouped in the plurality of groups A according to an algorithm that increases the chances that a codebook search of the groups A will yield an optimum result that is better than if the pulses are arbitrarily grouped.
- 11. A method comprising conducting a random excitation codebook search in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec using one or more tracks of pulse positions, wherein at least one of the tracks is subdivided into at least two sub-tracks and pulse positions are grouped in the at least two sub-tracks corresponding to respective odd maximums and even maximums of the absolute value of a signal b(n).
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13. A method according to 11 further wherein the number of tracks is 5 and the number of sub-tracks is 2, and the number of pulse positions in each sub-track is 4.
- 14. A method comprising grouping pulse positions to increase the likelihood that a codebook search of the resulting combinations of pulse positions will yield an acceptable result, wherein the method is performed in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec, wherein the pulse positions are grouped based on relative importance of pulse positions.
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17. A method comprising:
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computing the absolute magnitude |b(n)| of a signal b(n) in an Algebraic Code-Excited-Linear-Prediction (ACELP) codec;
arranging pulse positions in each track in the descending order of computed |b(n)|;
splitting the tracks into left (Ti0) and right (Ti1) sub-tracks;
filling left and right sub-tracks with interleaved pulse positions;
defining i0 as the pulse position corresponding to the maximum of |b(n)| over all tracks and its corresponding sub-track is mapped as the first sub-track for a codebook search, wherein the remaining sub-tracks are ordered cyclically;
setting position of pulse i1 to the local maximum of its corresponding sub-track;
searching the rest of the pulses in pairs by sequentially searching each of the pulse pairs;
reiterating the searching wherein the pulse starting positions are cyclically shifted; and
choosing the pulse positions for the iteration that yields the minimum mean square error (MSE) as the optimum. - View Dependent Claims (18, 19)
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- 20. An apparatus comprising a voice signal analysis unit for producing an encoded voice signal in response to a voice signal, wherein the analysis unit includes a codebook search unit that groups pulse positions according on relative importance to reduce the complexity of the codebook search required to produce an acceptable synthesized voice from one or more code vectors produced from the codebook search.
- 24. An apparatus comprising a microphone for receiving an analog voice signal, a voice signal analysis unit for producing an encoded voice signal in response to a voice signal, wherein the analysis unit includes a codebook search unit that groups pulse positions according to relative importance of pulse position to reduce the complexity of the codebook search required to produce an acceptable synthesized voice from one or more code vectors produced from the codebook search.
- 31. An Apparatus comprising a computing device, a data storage medium and an input-output device, and further including an operating system stored at least in part in the storage medium and operable on the computing device, and further including a voice signal analysis unit for producing an encoded voice signal in response to a voice signal, wherein the analysis unit includes a codebook search unit that groups pulse positions according to relative importance of the pulse positions to reduce the complexity of the codebook search required to produce an acceptable synthesized voice from one or more code vectors produced from the codebook search.
Specification