Center signal scaling using signal-to-downmix ratios

A novel method for scaling the level of the virtual center in audio signals is proposed. The input signals are processed in the time-frequency domain such that direct sound components having approximately equal energy in all channels are amplified or attenuated. The real-valued spectral weights are obtained from the ratio of the sum of the power spectral densities of all input channel signals and the power spectral density of the sum signal. Applications of the presented method are upmixing two-channel stereophonic recordings for its reproduction using surround sound set-ups, stereophonic enhancement, dialogue enhancement, and as preprocessing for semantic audio analysis.