Performance Comparison of Linear Prediction based Vocoders in Linux Platform

TL;DR

This paper implements and compares linear prediction based vocoders (CELP, LD-CELP, MELP) on Linux, evaluating their speech quality at various bit rates through subjective and waveform analysis.

Contribution

It provides a software implementation and performance comparison of different linear prediction vocoders on Linux platform, including subjective quality assessment.

Findings

LD-CELP offers higher speech quality at higher bit rate.

MELP and CELP produce comparable speech quality.

All vocoders were successfully implemented and tested on Linux.

Abstract

Linear predictive coders form an important class of speech coders. This paper describes the software level implementation of linear prediction based vocoders, viz. Code Excited Linear Prediction (CELP), Low-Delay CELP (LD-CELP) and Mixed Excitation Linear Prediction (MELP) at bit rates of 4.8 kb/s, 16 kb/s and 2.4 kb/s respectively. The C programs of the vocoders have been compiled and executed in Linux platform. Subjective testing with the help of Mean Opinion Score test has been performed. Waveform analysis has been done using Praat and Adobe Audition software. The results show that MELP and CELP produce comparable quality while the quality of LD-CELP coder is much higher, at the expense of higher bit rate.