A Dual Audio Transcoding Algorithm for Digital Multimedia Broadcasting Services

In this paper, we propose a dual audio transcoding algorithm to service high quality audio streams using a broadcasting network comprising heterogeneous audio formats. As two typical cases, audio transcodings from TDTV to T-DMB and S-DMB services are considered. While the Korean DTV audio standard employs the Dolby AC-3, the Korean T-DMB and Korean S-DMB services use the MPEG-4 BSAC and the MPEG-4 HE-AAC audio coding technologies, respectively. In the proposed algorithm, the bit allocation information of AC-3 is reused in the process of BSAC and HE-AAC encodings and the nested loops are reestablished as two independent loops, which saves significant amount of computational cost. In overall, the transcoding algorithm can save about 65% of computational cost for the BSAC encoding and 31% of HE-AAC encoding. Subjective quality evaluations show that the proposed algorithm has mean diffgrades of -0.02 and -0.01 relative to the tandem method. Due to its computational simplicity and effective performance, the proposed algorithm is suitable for the mobile multimedia services.