Workload characterization and cost-quality tradeoffs in MPEG-4 decoding on resource-constrained devices

There has been a lot of interest in the embedded systems community on architectures and design methods that are targeted towards multimedia applications. This trend is pri marily motivated by the proliferation of resource and power-constrained portable devices (such as mobile phones and PDAs), a major portion of whose workload is made up of multimedia applications. In this paper, we investigate the tradeoffs between video quality and the processor cycle requirements in such resource-constrained devices, in the particular context of MPEG-4 decoding using an open source codec called XviD. The XviD codec implements a number of powerful coding tools from MPEG-4, which are organized as profiles and levels. Given the specification of an architecture on which an XviD decoder is implemented, the work presented here would guide a multimedia applications developer in selecting appropriate profiles and levels for the corresponding encoder application. While the selection of such profiles has so far been primarily influenced by the network bandwidth in the case of video streaming, our work stresses the importance of additionally taking into account the architecture of the device running the decoder application. Although the relevance of this observation is increasingly being realized, sufficient work has not yet been done to provide guidelines on how to systematically make such selections. This work attempts to address this shortcoming.