Acoustical Science and Technology
Online ISSN : 1347-5177
Print ISSN : 1346-3969
ISSN-L : 0369-4232
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Harmonic vector excitation coding of speech
Masayuki Nishiguchi
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2006 Volume 27 Issue 6 Pages 375-383

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Abstract

A coding algorithm for speech called harmonic vector excitation coding (HVXC) has been developed that encodes speech at very low bit rates (2.0–4.0 kbit/s). It breaks speech signals down into two types of segments: voiced segments, for which a parametric representation of harmonic spectral magnitudes of LPC residual signals is used; and unvoiced segments, for which the CELP coding algorithm is used. This combination provides near toll-quality speech at 4.0 kbit/s, and communication-quality speech at 2.0 kbit/s, thus outperforming FS1016 4.8-kbit/s CELP. This paper discusses the encoder and decoder algorithms for HVXC, including fast harmonic synthesis, time scale modification, and pitch-change decoding. Due to its high coding efficiency and new functionality, HVXC has been adopted as the ISO/IEC International Standard for MPEG-4 audio.

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© 2006 by The Acoustical Society of Japan
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