2728797
Generalized Rate Analysis for Media-Processing Platforms
In this paper we address the "rate analysis" problem for media-processing platforms consisting of multiple processor cores connected in a pipelined fashion. More precisely, we aim at determining fight bounds on the rates at which multimedia streams can be fed into such architectures. These bounds depend on architectural constraints (e.g. the available on-chip memory, bus arbitration policies, etc), as well as the application characteristics (e.g. application partitioning and mapping, workload rates generated by different tasks, etch The proposed framework for rate analysis can be used for fast design space exploration to determine how these bounds change with different architectural parameters, mapping of the application, or changing the QoS requirements associated with the input streams
16964204
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.
2987131
Interface-Based Rate Analysis of Embedded Systems
Interface-based design is now considered to be one of the keys to tackling the increasing complexity of modern embedded systems. The central idea is that different components comprising such systems can be developed independently and a system designer can connect them together only if their interfaces match, without knowing the details of their internals. We use the concept of rate interfaces for compositional (correct-by-construction) design of embedded systems whose components communicate through data streams. Using the associated rate interface algebra, two components can be connected together if the output rate of one component is "compatible" with the input rate of the other component. We formalize this notion of compatibility and show that such an algebra is non-trivial because it has to accurately model the burstiness in the arrival rates of such data streams and the variability in their processing requirements. We discuss how rate interfaces simplify compositional design and at the same time help in functional and performance verification which would be difficult to address otherwise. Finally, we illustrate these advantages through a realistic case study involving a component-based design of a multiprocessor architecture running a picture-in-picture application
5822903
Automatic Accurate Live Memory Analysis for Garbage-Collected Languages
This paper describes a general approach for automatic and accurate live heap space and live heap space-bound analyses for high-level languages. The approach is based on program analysis and transformations and is fully automatic. The space-bound analysis produces accurate (tight) upper bounds in the presence of partially known input structures. The analyses have been implemented and experimental results confirm their accuracy.
769251
An improved study of real-time fluid simulation on GPU
Taking advantage of the parallelism and programmability of GPU, we solve the fluid dynamics problem completely on GPU. Different from previous methods, the whole computation is accelerated in our method by packing the scalar and vector variables into four channels of texels. In order to be adaptive to the arbitrary boundary conditions, we group the grid nodes into different types according to their positions relative to obstacles and search the node that determines the value of the current node. Then we compute the texture coordinates offsets according to the type of the boundary condition of each node to determine the corresponding variables and achieve the interaction of flows with obstacles set freely by users. The test results prove the efficiency of our method and exhibit the potential of GPU for general-purpose computations. Copyright © 2004 John Wiley & Sons, Ltd.
2394019
A computational model for periodic pattern perception based on frieze and wallpaper groups
We present a computational model for periodic pattern perception based on the mathematical theory of crystallographic groups. In each N-dimensional Euclidean space, a finite number of symmetry groups can characterize the structures of an infinite variety of periodic patterns. In 2D space, there are seven frieze groups describing monochrome patterns that repeat along one direction and 17 wallpaper groups for patterns that repeat along two linearly independent directions to tile the plane. We develop a set of computer algorithms that "understand" a given periodic pattern by automatically finding its underlying lattice, identifying its symmetry group, and extracting its representative motifs. We also extend this computational model for near-periodic patterns using geometric AIC. Applications of such a computational model include pattern indexing, texture synthesis, image compression, and gait analysis.
887136
Value Functions for RL-Based Behavior Transfer: A Comparative Study
Temporal difference (TD) learning methods (Sutton & Barto 1998) have become popular reinforcement learning techniques in recent years. TD methods, relying on function approximators to generalize learning to novel situations, have had some experimental successes and have been shown to exhibit some desirable properties in theory, but have often been found slow in practice. This paper presents methods for further generalizing across tasks, thereby speeding up learning, via a novel form of behavior transfer. We compare learning on a complex task with three function approximators, a CMAC, a neural network, and an RBF, and demonstrate that behavior transfer works well with all three. Using behavior transfer, agents are able to learn one task and then markedly reduce the time it takes to learn a more complex task. Our algorithms are fully implemented and tested in the RoboCup-soccer keepaway domain.
37778003
Automatic Accurate Cost-Bound Analysis for High-Level Languages
This paper describes a language-based approach for automatic and accurate cost-bound analysis. The approach consists of transformations for building cost-bound functions in the presence of partially known input structures, symbolic evaluation of the cost-bound function based on input size parameters, and optimizations to make the overall analysis efficient as well as accurate, all at the source-language level. The calculated cost bounds are expressed in terms of primitive cost parameters. These parameters can be obtained based on the language implementation or can be measured conservatively or approximately, yielding accurate, conservative, or approximate time or space bounds. We have implemented this approach and performed a number of experiments for analyzing Scheme programs. The results helped confirm the accuracy of the analysis.