Proceedings of the IEEK Conference (대한전자공학회:학술대회논문집)

The Institute of Electronics and Information Engineers (대한전자공학회)
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The Research of Reducing the Fixed Codebook Search Time of G.723.1 MP-MLQ

G.733.1 MP-MLQ 고정 코드북 검색 시간 단축에 관한 연구

  • 김정진 (숭실대학교 정보통신공학과) ;
  • 장경아 (숭실대학교 정보통신공학과) ;
  • 목진덕 (숭실대학교 정보통신공학과) ;
  • 배명진 (숭실대학교 정보통신공학과) ;
  • 홍성훈 (C&S Technology 음성처리개발팀) ;
  • 성유나 (C&S Technology 음성처리개발팀)
  • Published : 1999.11.01
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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 MO-MLQ. Since 6.3kbps MP-MLQ requires large amount of computation for fixed codebook search, it is difficult to realize real time processing. In order to improve the problem this paper proposes the new method that reduces the processing time up to about 50% of codebook search time. We first decide the grid bit, then search the codebook. Grid bit is selected by comparison between synthetic speech, which is synthesized with only odd or even pulses of target vector. and DC removed original speech. As a result, we reduced the total processing time of G.723.1 MP-MLQ up to about 26.08%. In objective quality test 11.19㏈ of segSNR was obtained, and in subjective quality test there was almost no speech degradation.

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