MPEG-4 HVXC real-time implementation on floating point DSP

HVXC(Harmonic and Vector eXcitation Coding) coder is a part of an MPEG-4 audio coder and needs large computing time. It encodes unvoiced frames and voiced frames using CELP coder and MBE coder, respectively. This structural complexity is major difficulty in real-time implementation of the HVXC coder In this paper dominant functions are selected that occupy most of computing time of the HVXC coder and optimized in C and assembly language. Furthermore the DSP internal program memory was used for program cache to reduce the overhead due, to memory I/O operation. Operations of large complexity routines and those with reference table are performed in internal data memory using DAM(direct memory access). As a result, real-time implementation of HVXC coder of 20 msec frame-length was achieved.