| 摘要 |
The present invention relates to a method and device for conducting a search in a codebook. This codebook consists of a set of pulse amplitude/position combinations each defining a number L of positions p and comprising both zero-amplitude pulses and non-zero-amplitude pulses assigned to respective positions p = 1, 2, ...L of the combination. Also, each non-zero-amplitude pulse assumes one of q possible amplitudes. According to the method, the positions p of the non-zero-amplitude pulses of the combinations of the codebook are restrained in accordance with a set of tracks of pulse positions, the pulse positions of each track being interleaved with the pulse positions of the other tracks. A subset of pulse amplitude/position combinations is pre-selected from the codebook in relation to the sound signal, and only this subset of pulse amplitude/position combinations is searched to thereby reduce the complexity of the search. Pre-- selecting a subset of pulse amplitude/position combinations comprises pre--establishing, in relation to the sound signal, an amplitude/position function S p pre-assigning to the positions p = 1, 2, ...L valid amplitudes out of the q possible amplitudes. And the searching comprises searching only the pulse amplitude/position combinations of the codebook having non-zero-amplitude pulses which satisfy the pre-established function S p.
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