Optimisation of Multimedia Applications for the Philips Wasabi Multiprocessor System

Libavcodec is an open source software library that contains many different audio/video codecs. In this work, it is optimised and parallelised for the Philips Wasabi chip multiprocessor, which is currently being developed at Philips. Wasabi contains several DSPs and one or more general-purpose processors. The TriMedia-style optimisations (in particular utilising the SIMD custom operations) improve the performance of the MPEG2 and MPEG4 decoders by approximately 41% and 30%, respectively. Parallelisation of the video encoder achieves a linear speedup for up to 6 CPUs. Thereafter, it slightly levels off. Additional work is required to make libavcodec more scalable so that it can exploit more processors efficiently. In addition, an interface between the TriMedia(s) executing libavcodec and the general-purpose processors running host applications that use libavcodec is proposed. This interface enables applications to efficiently use libavcodec running on the TriMedias, without having to port the applications themselves to the TriMedia. Keywords— libavcodec; TriMedia; multiprocessor; optimisation; VLIW architecture