A Time-Frequency Hybrid Downmixing Method for AC-3 Decoding

In this letter, a time-frequency hybrid downmixing method is proposed for AC-3 decoding. The proposed method consists of downmixing frequency coefficients of long blocks and short blocks respectively, computing long and short inverse modified discrete cosine transforms (IMDCTs), and adding operation. Compared with one reported fast frequency-domain downmixing method, the proposed method does not need frequency coefficients conversion between long and short blocks, and has approximately 26% and 32% reduction in numbers of additions and multiplications, respectively.