Patent ID: 8046217
Filing Date: 2011-10-25
Classification: G10L,H04S

Abstract:
1. An audio decoder which decodes a bitstream and reproduces two audio signals, the bitstream including (i) first coded data indicating a downmix signal obtained by downmixing the two audio signals, (ii) second coded data indicating a gain ratio D between the two audio signals, and (iii) third coded data indicating a phase difference θ between the two audio signals, wherein the third coded data is a value of cos θ associated with the phase difference θ, wherein said audio decoder comprises: wherein said determination unit is operable to determine, as the two phase rotators, either two complex numbers e wherein the bitstream further includes fourth coded data representing phase polarity information S indicating which of the two audio signals has a phase that is ahead of a phase of another of the two audio signals, wherein said separation unit is operable to generate the two separation signals by respectively multiplying, with the frequency domain signal transformed from the downmix signal by said transformation unit, either the two complex numbers or the two conjugate complex numbers associated with the phase polarity information S indicated as the fourth coded data, and wherein said inverse transformation unit accurately reproduces an advancement or a delay of the phase of each of the two audio signals by inversely transforming the two separation signals generated by multiplying, with the frequency domain signal transformed from the downmix signal by said transformation unit, either the two complex numbers or the two conjugate complex numbers associated with the phase polarity information S indicated as the fourth coded data.