Adaptive mapping to resource availability for dynamic wavelet-based applications

Study and implementation of wavelet-based video coding for dynamic transition environments

“…While it is feasible to remove these explicit non-linear loop and index expressions through code rewriting techniques, in this case by unrolling the WT level loop, this does not change the fact that the corresponding dependencies remain implicitly present in the code, since a level-k sample will still depend on an exponentially increasing amount of samples from each lower WT level. This makes automated optimization strategies difficult to apply to wavelet-based applications, because they cannot suitably handle these non-linear dependencies and because the code unrolling techniques increase the complexity of the internal representation used in these strategies, making it difficult to find a good solution, as was shown for the automated memory hierarchy mapping tool MH [Geelen 2006] and for the automated memory compaction tool [Ferentinos 2003. Each level of the FWT consists of a lowpass (L) and a highpass (H) filtering followed by a subsampling operation.…”

“…• Problem formulation and the proposed switching principle [Ferentinos 2003, Geelen 2006]: The difficulty of automated tools to find optimal data mappings, for applications with non-linear dependencies like the Wavelet Transform, has been demonstrated and initially solved by subdividing (localizing) the basic processing data-block (Chapter 3). By generalizing the initial approach, we have proposed a run-time switching principle between different implementation mechanisms (localizations) of wavelet-based applications.…”

“…During the preprocessing, pointer accesses are converted to array accesses [van Engelen 2001, Franke 2003, other constructs that cannot be modeled by the geometrical model are hidden away [Palkovic 2004], functions are selectively inlined [Absar 2003] and the code may be rewritten in Dynamic Single Assignment conversion (DSA) form [Feautrier 1988, Vanbroekhoven 2003].…”

“…Later in the design flow, they enable storing the data in smaller memories, closer to the data paths. The state of the art in GLT traditionally focuses on one cost function resulting in one optimal solution for GLT [van Swaaij 1992, Franssen 1994, Danckaert 2001, Verdoolaege 2005. [Palkovic 2007] shows that an extension of this approach towards different cost-functions resulting in trade-offs is needed.…”

“…Influence of dynamics on mapping guidelines [Ferentinos 2007]: The formalization of the miss-rate behavior for temporal locality has initially focused on static, 2D Wavelet Transforms. In contrast, wavelet-based video codecs often make use of motion-dependent, 3D Wavelet Transforms.…”