LP/WLP Hybrid Scheme for Quality Improvement of TCX Coders Operating at Low Bit Rates

Tung-chin LEE  Young-cheol PARK  Dae-hee YOUN 

Publication
IEICE TRANSACTIONS on Information and Systems  Vol.E95-D  No.7  pp.2017-2020
Publication Date: 2012/07/01
Online ISSN: 1745-1361
Print ISSN: 0916-8532
Type of Manuscript: LETTER
Category: Speech and Hearing
Keyword: 
warped linear prediction (WLP),  linear prediction,  audio coding,  TCX,  low bit rate, 

Full Text: PDF(1.1MB)

Summary: 
In this paper, we propose a switchable linear prediction (LP)/warped linear prediction (WLP) hybrid scheme for the transform coded excitation (TCX) coder, which is adopted as a core codec in AMR-WB+ and USAC. The proposed algorithm selects either an LP or WLP filter on a per-frame basis. To provide a smooth transitions between LP and WLP frames, a window switching scheme is developed using sine and rectangular windows. In addition, a Gaussian Mixture Model (GMM)-based classification module is used to determine the prediction mode. Through a subjective listening test it was confirmed that the proposed LP/WLP switching scheme offers improved sound quality.