High quality MELP coding at bit-rates around 4 kb/s
نویسندگان
چکیده
Recently, a number of coding techniques have been reported to achieve near toll quality synthesized speech at bit-rates around 4 kb/s. These include variants of Code Excited Linear Prediction (CELP), Sinusoidal Transform Coding (STC) and Multi-Band Excitation (MBE). While CELP has been an effective technique for bit-rates above 6 kb/s, STC, MBE, Waveform Interpolation (WI) and Mixed Excitation Linear Prediction (MELP) [1, 2] models seem to be attractive at bit-rates below 3 kb/s. In this paper, we present a system to encode speech with high quality using MELP, a technique previously demonstrated to be effective at bit-rates of 1.6–2.4 kb/s. We have enhanced the MELP model producing significantly higher speech quality at bit-rates above 2.4 kb/s. We describe the development and testing of a high quality 4 kb/s MELP coder.
منابع مشابه
Hybrid MELP/CELP coding at bit rates from 6.4 to 2.4 kb/s
This paper describes extensions of the 4 kb/s hybrid MELP/CELP coder, up to 6.4 kb/s and down to 2.4 kb/s. The baseline 4 kb/s coder uses three coding modes: MELP in strongly voiced speech frames, CELP with pitch prediction in weakly voiced frames, and CELP with stochastic excitation in unvoiced frames. To minimize switching artifacts between parametric MELP and waveform CELP coding, an alignme...
متن کاملA 1.7 kb/s MELP coder with improved analysis and quantization
This paper describes our new Mixed Excitation Linear Predictive (MELP) coder designed for very low bit rate applications. This new coder, through algorithmic improvements and enhanced quantization techniques, produces better speech quality at 1.7 kb/s than the new U.S. Federal Standard MELP coder at 2.4 kb/s. Key features of the coder are an improved pitch estimation algorithm and a Line Spectr...
متن کاملA mixed sinusoidally excited linear prediction coder at 4 kb/s and below
There is currently a great deal of interest in the development of speech coding algorithms capable of delivering toll quality at 4 kb/s and below. For synthesizing high quality speech, accurate representation of the voiced portions of speech is essential. For bit rates of 4 kb/s and below, conventional Code Excited Linear Prediction (CELP) may likely not provide the appropriate degree of period...
متن کاملStrategies to improve the performance of very low bit rate speech coders and application to a variable rate 1.2 kb/s codec - Vision, Image and Signal Processing, IEE Proceedings-
This paper presents several strategies to improve the performance of very low bit rate speech coders and describes a speech codec that incorporates these strategies and operates at an average bit rate of 1.2 kb/s. The encoding algorithm is based on several improvements in a mixed multiband excitation (MMBE) linear predictive coding (LPC) structure. A switched-predictive vector quantiser techniq...
متن کاملImplementation of an enhanced fixed point variable bit-rate MELP vocoder on TMS320C549
In this paper, a fixed point Variable Bit-Rate (VBR) Mixed Excitation Linear Predictive Coding (MELP TM ) vocoder is presented. The VBR-MELP vocoder is also implemented on a TMS320C54x and it achieves virtually indistinguishable federal standard MELP quality at bit-rates between 1.0 to 1.6 kb/s. The backbone of VBRMELP vocoder is similar to that of federal standard MELP. It utilizes a novel sub...
متن کامل