In present downmixing based multichannel coding standard, the downmixing process causes the ‘tone leakage’ problem by mixing different channels into one channel. In this paper a novel multichannel analysis method is proposed to reduce ‘tone leakage’ phenomenon with additive side information, the basic idea is to find subbands with largest spectrum difference and coding their spectrum envelope information. By analyzing the decoded signals, ‘leakage tones’ are identified and attenuated, then the original ones are reconstructed which meantime retain the original interchannel level difference (ICLD) of subbands unchanged. Result shows our method can improve subjective quality compared with HE-AAC (v2) codec with bit rate increasing slightly.
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