High speed codebook searching algorithm for the CELP vocoder in the internet-based environment

  • Authors:

  • So Yeon Min;Eun Sook Cho;Chul Jin Kim

  • Affiliations:

  • Dept. of Information & Telecommunication Eng., Seoul, Korea;Dept. of Software Engr., Seoil College, Seoul, Korea;Digital Solution Center, Samsung Electronics Co., Seoul, Korea

  • Venue:
  • ICCSA'06 Proceedings of the 2006 international conference on Computational Science and Its Applications - Volume Part II
  • Year:
  • 2006

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Abstract

In general CELP type vocoders provide good speech quality around 4.8kbps. Among them, G.723.1 developed for Internet Phone and videoconferencing includes two vocoders, 5.3kbps ACELP and 6.3kbps MP-MLQ. Since 6.3kbps MP-MLQ requires large amount of computation for the fixed codebook search, it is difficult to realize real time processing for the internet-based environment. In order to improve the problem this paper proposes the new method that reduces the processing time up to about 30% of codebook search time. We first decide the grid bit, and then search the codebook. Grid bit is selected by comparison between the DC-removed original speech and synthesized speech, which is synthesized with only even or odd pulses of target vector.