Efficient MDCT-Based Multi-Channel Coding with Perceptual Whitening and Broadband ILD Compensation

Stereo and multi-channel audio coding for mobile communication applications is challenging due to bitrate, latency and computational complexity constraints. To address these constraints, a novel MDCT-based stereo coding scheme is introduced. A key feature of this scheme is the broadband inter-channel level compensation of the spectrally and temporally whitened channels, followed by a robust mechanism for selecting between Mid/Side and Left/Right coding for each frequency sub-band. For lower bitrates, inter-channel time and phase difference compensation methods are additionally utilized. Enhancements comprising stereo coding of spectral and temporal noise shaping parameters and stereo-aware bandwidth extension further increase coding efficiency. The paper outlines the fundamental concepts of this MDCTbased stereo coding incorporated into the newly introduced 3GPP IVAS codec and their extension to multi-channel coding. Finally, the IVAS codec is compared to state-of-the-art counterparts, demonstrating its advantages in communication scenarios across a wide range of content types.