DocumentCode :
290370
Title :
Implementation and performance of an 8-kbit/s conjugate structure CELP speech coder
Author :
Kataoka, Akitoshi ; Moriya, Takehiro ; Hayashi, Shinji
Author_Institution :
NTT Human Interface Labs., Tokyo, Japan
Volume :
ii
fYear :
1994
fDate :
19-22 Apr 1994
Abstract :
This paper presents a high-quality 8-kbit/s speech coder (conjugate structure CELP: CS-CELP) that is a candidate for standardization by the ITU-T (formerly CCITT). To achieve high-quality for two types of speech (IRS and non-IRS (flat) speech) and real-time implementation, CS-CELP has been revised by two novel schemes. To handle two types of speech, the LSP parameters are quantized by multistage VQ with fourth-order interframe MA prediction. This scheme has little spectrum distortion, even if the two types of speech have many variations of the LSP parameters. The computational complexity of the implementation is reduced for adaptive and fixed-shape codebooks without degrading the speech quality. Multistage selection is adopted in the adaptive codebook; this selection uses a truncated impulse response. Improved pre-selection is proposed in the fixed-shape codebook. Subjective testing indicates that the quality of CS-CELP is equivalent to that of the 32-kbit/s ADPCM under error-free conditions for IRS and non-IRS speech. It also operates in real time using fixed-point DSP chips
Keywords :
digital arithmetic; digital signal processing chips; linear predictive coding; moving average processes; speech coding; transient response; vector quantisation; vocoders; 8 kbit/s; ADPCM; CCITT; CS-CELP; ITU-T; LSP parameters; adaptive codebooks; computational complexity; conjugate structure CELP; fixed-point DSP chips; fixed-shape codebooks; fourth-order interframe MA prediction; multistage VQ; performance; speech coder; speech quality; standardization; subjective testing; truncated impulse response; Computational complexity; Decoding; Degradation; Filters; Humans; Laboratories; Linear predictive coding; Speech synthesis; Standardization; Testing;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Acoustics, Speech, and Signal Processing, 1994. ICASSP-94., 1994 IEEE International Conference on
Conference_Location :
Adelaide, SA
ISSN :
1520-6149
Print_ISBN :
0-7803-1775-0
Type :
conf
DOI :
10.1109/ICASSP.1994.389710
Filename :
389710
Link To Document :
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