Spatialization Parameter Estimation in MDCT Domain for Stereo Audio

For representing multi-channel audio at low bit rate parametric coding techniques are used in many audio coding standards. An MDCT domain parametric stereo coding algorithm which represents the stereo channels as the linear combination of the ‘sum ’ channel derived from the stereo channels and a reverberated channel generated from the ‘sum ’channel has been reported in literature. This model is inefficient in capturing the stereo image since only four parameters per sub-band is used as spatialization parameters. In this work we improve this MDCT domain parametric coder with an augmented parameter extraction scheme using an additional reverberated channel. We further modify the scheme by using orthogonalized de-correlated channels for analysis and synthesis of parametric stereo. A synthesis scheme with perceptually scaled parameter set is also introduced. Finally we present, subjective evaluation of the different parametric stereo schemes using MUSHRA test and the increased the perceptual audio quality of the synthesized signals are evident from these test results