Speech coding with time-varying bit allocations to excitation and LPC parameters

Author

Jayant, N.S. ; Chen, J.H.

Author_Institution

AT&T Bell Lab., Murray Hill, NJ, USA

fYear

1989

fDate

23-26 May 1989

Firstpage

65

Abstract

The authors explore the benefits of time-varying bit allocation to excitation and LPC (linear predictive coding) parameters for the case of codebook-excited LPC. The overall bit rate in the experiment was 4.8, 6.4, or 8.0 kb/s. In each case, permissible bit rates for the LPC component were 0, 24, 36, or 48 bits per frame, one of which was selected for each speech frame using a brute-force search maximum performance. Average SNR gains over conventional time-invariant methods were modest, on the order of 1 to 2 dB, but gains for certain speech segments were as high as 3 to 5 dB. Perceptually, gains due to variable bit allocation were most noticeable in the 6.4 kb/s system, especially with female speakers. However, even in this case, the benefits of flexible bit allocation were somewhat offset by distortions due to other inadequacies in the coding algorithm

Keywords

encoding; filtering and prediction theory; speech analysis and processing; 4.8 kbit/s; 6.4 kbit/s; 8 kbit/s; CELP; LPC parameters; SNR gains; codebook-excited LPC; excitation parameters; linear predictive coding; speech coding; time-varying bit allocation; Bit rate; Gain; Linear predictive coding; Resource management; Signal to noise ratio; Speech analysis; Speech coding; Speech enhancement; Speech synthesis; Transform coding;

fLanguage

English

Publisher

ieee

Conference_Titel

Acoustics, Speech, and Signal Processing, 1989. ICASSP-89., 1989 International Conference on

Conference_Location

Glasgow

ISSN

1520-6149

Type

conf

DOI

10.1109/ICASSP.1989.266364

Filename

266364