A RISC/DSP dual-core platform for portable media application named GEM-SOC is presented in this paper. RISC is responsible for control related tasks and running OS, DSP is in charge of media applications and works as a slave for RISC. Mailbox based shared-memory inter-core communication mechanism is used in this platform. The GEM-SOC is fabricated in a 0.18 mum 6LM SMIC standard cell technology, occupies about 25 mm2, operates at 166 MHz, and consumes 0.6 Watts. Ogg Vorbis audio application has been developed on this platform and results show that GEM-SOC can achieve real time decode at 37.68MHz with communication overhead at 2.64-2.77%