Efficient statistics-based algebraic codebook search algorithms derived from RCM for an ACELP speech coder

Tzu Hung Lin, Cheng Yu Yeh*, Shaw-Hwa Hwang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Applied to an algebraic codebook search conducted on an algebraic code-excited linear-prediction (ACELP) speech coder, two improved versions of reduced candidate mechanism (RCM), designated as Fixed-G1-RCM and Fixed-2Track-RCM, are presented in this study for further search performance improvement. It is mainly derived from two major research findings in a piece of our prior work. The first finding is that a pulse with a high contribution in a track is more likely to serve as the optimal pulse in the optimal vector pertaining to the track, and the second is that the speech quality can be well maintained at a search accuracy above 50%. In this proposal, the trade off can be tuned between the search accuracy and the search complexity so as to reach a nearly consistent speech quality. With this presented search algorithm implemented on a G.729A speech codec, it is experimentally demonstrated that either Fixed-G1-RCM (N = 3), or Fixed-2Track-RCM (M = 2, N = 3, or M = 3, N = 4) can provide a highly superior search performance relative to a global pulse replacement method (iteration = 2) and an iteration-free pulse replacement method.

Original languageEnglish
Pages (from-to)410-419
Number of pages10
JournalInformation Technology and Control
Volume44
Issue number4
DOIs
StatePublished - 1 Jan 2015

Keywords

  • Algebraic code-excited linear-prediction (ACELP)
  • Algebraic codebook search
  • Reduced candidate mechanism (RCM)
  • Speech codec
  • VoIP

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