Dynamic configuration of dataflow graph topology for DSP system design [video encoder example]

Dataflow is widely used for designing DSP applications. Despite its intrinsic advantages, one weak point is its difficulty in flexible expression of applications with data dependent change in execution structure. This paper suggests an approach to providing dynamically configured dataflow graph topologies using a new modeling and synthesis technique called DGT (dynamic graph topology). DGT builds on PSDF semantics (B. Bhattacharya et al, IEEE Tran. on Sig. Proc., vol.49(10), p.2408-2421, 2001). All possible graph topologies for a given graph are obtained at compile time and the corresponding graph based on parameters and data is dynamically set up in an efficient manner at runtime before the invocation of the associated graph. Systematic methods for reducing code and buffer size are applied based on characteristics of each configured graph. We have compared DGT against conventional modeling approaches through a detailed case study of an MPEG 2 video encoder system, and our experiments demonstrate the efficiency of the DGT approach.