A novel variable-rate MELP speech coder

Author

Manxia, Tie ; Dusheng, Wang ; Changxin, Fan

Author_Institution

Inst. of Inf. Sci., Xidian Univ., Xi´´an, China

Volume

2

fYear

2000

fDate

2000

Firstpage

693

Abstract

In MELP coder, LPC coefficients are quantized to 25 bit/frame by MSVQ. The overall bit of MELP is 54 bit/frame, so more than 45% of the required bandwidth is spent on transmission of LPC coefficients. In this paper, based on LPC adaptive forward-backward quantization, a novel variable-rate MELP coder is proposed, in which linear prediction is done by using either the currently (forward LPC) or previously decoded (backward LPC) speech frame. The backward LPC scheme shall be applied, i.e., the LPC coefficients based on the previously decoded optimal speech frame are used to encode the current frame and only the time delay shall be transmitted to the decoder, so, average LPC bit number becomes smaller. Computer simulation shows significant average overall bit rate reduction is achieved without compromising the decoded speech quality

Keywords

adaptive codes; decoding; linear predictive coding; speech coding; speech intelligibility; variable rate codes; vector quantisation; LPC adaptive forward-backward quantization; LPC coefficients quantization; MSVQ; PCM format; average LPC bit number; average overall bit rate reduction; backward LPC speech frame; bandwidth; computer simulation; decoded speech quality; forward LPC speech frame; linear predictive coding; optimal speech frame; time delay; variable-rate MELP speech coder; Bandwidth; Bit rate; Decoding; Delay effects; Distortion measurement; Information science; Linear predictive coding; Quantization; Speech coding; Vocoders;

fLanguage

English

Publisher

ieee

Conference_Titel

Signal Processing Proceedings, 2000. WCCC-ICSP 2000. 5th International Conference on

Conference_Location

Beijing

Print_ISBN

0-7803-5747-7

Type

conf

DOI

10.1109/ICOSP.2000.891605

Filename

891605