Low delay LPC and MDCT-based audio coding in the EVS codec
Guillaume Fuchs, Christian R. Helmrich, Goran Markovic, Matthias Neusinger, Emmanuel Ravelli, Takehiro Moriya
Abstract
Speech coders operating in time domain can be extended with a frequency domain mode to improve encoding of music, even though this is challenging at low delay. In such a scenario, the short analysis window limits the benefit of the transform coder, while a delayless switch between the two coders constrains the system further. The paper presents an LPC and MDCT-based audio coder part of the new 3GPP codec for Enhanced Voice Services, which aims to solve the issues. Several advanced coding tools are introduced to alleviate the constraints: transient handling is improved, harmonic structures are better preserved, and the modeling of the zero-quantized frequencies is enhanced. Test results show that the obtained low-delay switched coder brings a clear improvement over a speech coder and is competitive even in comparison to audio coders with higher delay.
BibTeX
@inproceedings{icassp2015_lowdelaylpcandmd,
title = {Low delay LPC and MDCT-based audio coding in the EVS codec},
author = {Guillaume Fuchs and Christian R. Helmrich and Goran Markovic and Matthias Neusinger and Emmanuel Ravelli and Takehiro Moriya},
booktitle = {ICASSP 2015},
year = {2015}
}