tailieunhanh - Báo cáo hóa học: " Vector Quantization of Harmonic Magnitudes in Speech Coding Applications—A Survey and New Technique"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Vector Quantization of Harmonic Magnitudes in Speech Coding Applications—A Survey and New Technique | EURASIP Journal on Applied Signal Processing 2004 17 2601-2613 2004 Hindawi Publishing Corporation Vector Quantization of Harmonic Magnitudes in Speech Coding Applications A Survey and New Technique Wai C. Chu Media Laboratory DoCoMo Communications Laboratories USA 181 Metro Drive Suite 300 San Jose CA 95110 USA Email wai@ Received 29 October 2003 Revised 2 June 2004 Recommended for Publication by Bastiaan Kleijn A harmonic coder extracts the harmonic components of a signal and represents them efficiently using a few parameters. The principles of harmonic coding have become quite successful and several standardized speech and audio coders are based on it. One of the key issues in harmonic coder design is in the quantization of harmonic magnitudes where many propositions have appeared in the literature. The objective of this paper is to provide a survey of the various techniques that have appeared in the literature for vector quantization of harmonic magnitudes with emphasis on those adopted by the major speech coding standards these include constant magnitude approximation partial quantization dimension conversion and variable-dimension vector quantization VDVQ . In addition a refined VDVQ technique is proposed where experimental data are provided to demonstrate its effectiveness. Keywords and phrases harmonic magnitude vector quantization speech coding variable-dimension vector quantization spectral distortion. 1. INTRODUCTION A signal is said to be harmonic if it is generated by a series of sine waves or harmonic components where the frequency of each component is an integer multiple of some fundamental frequency. Many signals in nature including certain classes of speech and music obey the harmonic model and can be specified by three sets of parameters fundamental frequency magnitude of each harmonic component and phase of each harmonic component. In practice a noise model is often used in addition to the harmonic model to yield a high-quality