access icon free Algebraic codebook search strategy for an algebraic code-excited linear-prediction speech coder by means of reduced candidate mechanism and iteration-free pulse replacement

This work aims to present a combined version of reduced candidate mechanism (RCM) and iteration-free pulse replacement (IFPR) as a novel and efficient way to enhance the performance of algebraic codebook search in an algebraic code-excited linear-prediction speech coder. As the first step, individual pulse contribution in each track is given by RCM, and the value of N is then specified. Subsequently, the replacement of a pulse is performed through the search over the sorted top N pulses by IFPR, and those of 2–4 pulses are carried out by a standard IFPR. Implemented on a G.729A speech codec, this proposal requires as few as 20 searches, a search load tantamount to 6.25% of G.729A, 31.25% of the global pulse replacement method (iteration = 2), 41.67% of IFPR, but still provides a comparable speech quality in any case. The aim of significant search performance improvement is hence achieved in this work.

Inspec keywords: vocoders; iterative decoding; speech codecs; speech coding; algebraic codes; linear predictive coding; search problems

Other keywords: G.729A speech codec; algebraic codebook search strategy; iteration free pulse replacement; search performance improvement; RCM; IFPR; standard IFPR; global pulse replacement method; algebraic code excited linear prediction speech coder; reduced candidate mechanism

Subjects: Optimisation techniques; Speech processing techniques; Codecs, coders and decoders; Speech and audio coding

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http://iet.metastore.ingenta.com/content/journals/10.1049/iet-spr.2013.0433
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