Algebraic Codebook Search Using Iterative Pulse Placement
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Solution Overview
Problem
Existing speech coding techniques face challenges in efficiently searching large algebraic codebooks for wideband speech/audio applications, requiring minimal storage and rapid search methods to maintain high subjective quality and bit rate efficiency.
Innovation Solution
A method and device for searching an algebraic codebook during sound signal encoding, involving the calculation of a reference signal and iterative recomputation of the codebook gain to determine pulse positions and signs, optimizing the codevector computation for efficient search within the codebook.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large algebraic codebook is used for wideband speech/audio encoding, then speech quality is improved, but search complexity increases
Solution Approach 1:
The codebook search process is segmented into multiple stages: initial pulse position selection based on reference signal, iterative gain recomputation, and sequential pulse placement. This divides the complex search problem into manageable sub-tasks that can be executed efficiently
Solution Approach 2:
A reference signal is calculated beforehand to guide the selection of pulse positions. This preliminary action provides a roadmap for the search process, enabling the encoder to quickly identify promising codevectors without exhaustive search
2Productivity
If computational complexity is reduced for fast codebook search, then processing speed is improved, but speech quality may deteriorate
Solution Approach 1:
The codebook gain is dynamically recomputed at each iteration based on previously selected pulses. This adaptive approach allows the search to focus computational effort on the most promising directions while maintaining accuracy
Solution Approach 2:
The search process uses feedback from previously selected pulses to update the reference signal and guide subsequent pulse selections. This feedback mechanism ensures that each computational step builds on previous results, maintaining quality while reducing overall complexity
Data Source
AI summary
A method and device for searching an algebraic codebook during encoding of a sound signal, wherein the algebraic codebook comprises a set of codevectors formed of a number of pulse positions and a number of pulses distributed over the pulse positions. In the algebraic codebook searching method and device, a reference signal for use in searching the algebraic codebook is calculated. In a first stage, a position of a first pulse is determined in relation with the reference signal and among the number of pulse positions. In each of a number of stages subsequent to the first stage, (a) an algebraic codebook gain is recomputed, (b) the reference signal is updated using the recomputed algebraic codebook gain and (c) a position of another pulse is determined in relation with the updated reference signal and among the number of pulse positions. A codevector of the algebraic codebook is computed using the positions of the pulses determined in the first and subsequent stages, wherein a number of the first and subsequent stages corresponds to the number of pulses in the codevectors of the algebraic codebook.