RISC processor based speech codec implementation for emerging mobile multimedia messaging solutions

Mobile multimedia messaging (MMS) promises to provide a richer and versatile experience to the user along with new revenue streams for mobile service operators. MMS allows a full content range including images, audio, video and text in any combination. It delivers a location independent, total communication experience to the mobile customer. As proved by the success of short message service (SMS) in generating revenue MMS applications would be the essential drivers of continuous growth in new services beyond voice. Current programmable mobile handsets could suffice as platforms for simple MMS service introduction if the existing capability of the RISC processor of the handset is exercised fully. Speech, an important content in MMS has traditionally been encoded and decoded on DSP processors. This paper describes the challenges and techniques of implementing speech codecs on RISC processors. The specific speech codec implemented was GSM-AMR and the processor used was ARM9TDMI. The techniques described are generic and applicable to any speech codec and RISC processor platform.