Design and Implementation of MPEG-4 AAC Decoder on ARM Embedded System for CMMB Receiver

CMMB (China mobile multimedia broadcasting) adopts MPEG-4 HE AAC (high efficiency advanced audio coding) as its sound coding technology in video broadcast. In this paper, we first introduce the decoding flow of MPEG-4 HE AAC and its two key technologies, SBR (spectral band replication) and interbank. The IMDCT function was optimized especially because of its complicated calculation. Then we implemented the decoder into ARM embedded system and analyzed the complexity of each function in Linux OS. Test results indicate that the decoder can decode HE AAC bitstream with real time on the embedded system with ARM920T core.