An Efficient Implementation of Tiled Polymorphic Temporal Media

International audienceTiled Polymorphic Temporal Media (TPTM) are a convenient way to describe, compose and encode multimedia streams. This paper presents a TPTM encoding that allows simple and efficient implementation of both composition and rendering. In particular, an on-the-fly rendering procedure is provided in order to handle infinite (lazy) TPTM

From out-of-time design to in-time production of temporal media

The design a temporal media, a sequence of temporal media values such as notes, sounds, images, etc., is an out-of-time task. Fairly general out-of-time program constructs are available for such a purpose. For example , when writing a musical piece, a composer can traverse back and forth his creation. On the contrary, rendering a temporal media is an in-time task. The production of notes in a musical performance is bound to be coherent with the unceasing onward flow of time. It follows that some of the out-of-time programming constructs used for the creation of that pieces must have been reordered in order to produce the right media events in the right order and at the right time. In this paper, we propose a formal study of the interplay between these in-time and these out-of-time programing constructs. With an explicitly out-of-time design approach, we eventually show that simpler and more abstract declarative programming features become available, leaving to computers the tedious task of synchronizing and scheduling the media events to be produced in-time, upon demand

Tiled Polymorphic Temporal Media

International audienceTiled Polymorphic Temporal Media (Tiled PTM) is an algebraic approach to specifying the composition of multimedia values having an inherent temporal quality --- for example sound clips, musical scores, computer animations, and video clips. Mathematically, one can think of a tiled PTM as a tiling in the one dimension of time. A tiled PTM value has two synchronization marks that specify, via an effective notion of tiled product, how the tiled PTMs are positioned in time relative to one another, possibly with overlaps. Together with a pseudo inverse operation, and the related reset and co-reset projection operators, the tiled product is shown to encompass both sequential and parallel products over temporal media. Up to observational equivalence, the resulting algebra of tiled PTM is shown to be an inverse monoid: the pseudo inverse being a semigroup inverse. These and other algebraic properties are explored in detail. In addition, recursively-defined infinite tiles are considered. Ultimately, in order for a tiled PTM to be \emph{renderable}, we must know its beginning, and how to compute its evolving value over time. Though undecidable in the general case, we define decidable special cases that still permit infinite tilings. Finally, we describe an elegant specification, implementation, and proof of key properties in Haskell, whose lazy evaluation is crucial for assuring the soundness of recursive tiles. Illustrative examples, within the Euterpea framework for musical temporal media, are provided throughout

Structured reactive programming with polymorphic temporal tiles

International audienceIn functional reactive programming (FRP), system inputs and outputs are generally modeled as functions over continuous time (behaviors) whose future values are governed by sudden changes (events). In this approach, discrete events are embedded into piece-wise continuous behaviors. In the field of reactive music system programming, we develop an orthogonal approach that seems to better fit our need. Much like piano keys can be played and combined both in sequence and in parallel, we model system inputs and outputs as spatio-temporal combinations of what we call temporal values: continuous functions over time whose domain lays between two events: a start and a stop event. Various high level data types and program constructs can then be derived from such a model. They are shown to satisfy robust algebraic and category theoretic properties. Altogether, this eventually provides a simple, robust and elegant programming front-end, temporal tile programming, for reading, memorizing, stretching, combining and transforming flows of inputs into flows of outputs. Although at its infancy, the resulting approach has been experimentally validated for reactive and real-time music system programming

Pour un raffinement spatio-temporel tuilé

National audienceDans le domaine de la construction et de la manipulation par programme de flux média temporisé, nous étudions la problématique du raffinement, c'est-à-dire le problème de la substitution de flux élémentaires par des flux plus complexes. Dans le cas de construction purement séquentielle, la notion de liste permet de faire cela sans difficulté. C'est du raffinement temporel. Le bind de la monade liste permet de réaliser ces substitutions. En présence de parallélisme, les choses sont plus complexes : aucune construction ne semble s'imposer a priori. Dans cet article, nous montrons comment la modélisation par tuilage, qui explicite dans sa syntaxe les points de synchronisation qui doivent être préservés lors d'un raffinement, permet de définir, sans ambiguïté et tout aussi simplement que dans le cas des listes, un raffinement spatio-temporel. Incidemment, cette approche rompt avec l'usage usuel des monades en programmation fonctionnelle qui permettent de représenter la séquentialité. Sur la monade des tuiles comme sur la monade des listes, le bind permet aussi de modéliser le raffinement

Polymorphic Pipeline Array: A Flexible Multicore Accelerator for Mobile Multimedia Applications.

Mobile computing in the form of smart phones, netbooks, and PDAs has become an integral part of our everyday lives. Moving ahead to the next generation of mobile devices, we believe that multimedia will become a more critical and product-differentiating feature. High definition audio and video as well as 3D graphics provide richer interfaces and compelling capabilities. However, these algorithms also bring different computational challenges than wireless signal processing. Multimedia algorithms are more complex featuring more control flow and variable computational requirements where execution time is not dominated by innermost vector loops. Further, data access is more complex where media applications typically operate on multi-dimensional vectors of data rather than single-dimensional vectors with simple strides. Thus, the design of current mobile platforms requires re-examination to account for these new application domains. In this dissertation, we focus on the design of a programmable, low-power accelerator for multimedia algorithms referred to as a Polymorphic Pipeline Array (PPA). The PPA design is inspired by coarse-grain reconfigurable architectures (CGRAs) that consist of an array of function units interconnected by a mesh style interconnect. The PPA improves upon CGRAs by attacking two major limitations: scalability and acceleration limited to innermost loops. The large number of resources are fully utilized by exploiting both Lne-grain instruction-level and coarse-grain pipeline parallelism, and the acceleration is extended beyond innermost loops to encompass the whole region of applications. Various compiler and architectural optimizations are presented for CGRAs that form the basic building blocks of PPA. Two compiler techniques are presented that systematically construct the schedule with intelligent heuristics. Modulo graph embedding leverages graph embedding technique for scheduling in CGRAs and edgecentric modulo scheduling provides a communication-oriented way to address the scheduling problem. For architectural improvement, a novel control path design is presented that leverages the token network of dataflow machines to reduce the instructionmemory power. The PPA is designed with flexibility and programmability as first-order requirements to enable the hardware to be dynamically customizable to the application. A PPA exploit pipeline parallelism found in streaming applications to create a coarsegrain hardware pipeline to execute streaming media applications.Ph.D.Computer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64732/1/parkhc_1.pd

Architectural Support for Efficient Communication in Future Microprocessors

Traditionally, the microprocessor design has focused on the computational aspects of the problem at hand. However, as the number of components on a single chip continues to increase, the design of communication architecture has become a crucial and dominating factor in defining performance models of the overall system. On-chip networks, also known as Networks-on-Chip (NoC), emerged recently as a promising architecture to coordinate chip-wide communication. Although there are numerous interconnection network studies in an inter-chip environment, an intra-chip network design poses a number of substantial challenges to this well-established interconnection network field. This research investigates designs and applications of on-chip interconnection network in next-generation microprocessors for optimizing performance, power consumption, and area cost. First, we present domain-specific NoC designs targeted to large-scale and wire-delay dominated L2 cache systems. The domain-specifically designed interconnect shows 38% performance improvement and uses only 12% of the mesh-based interconnect. Then, we present a methodology of communication characterization in parallel programs and application of characterization results to long-channel reconfiguration. Reconfigured long channels suited to communication patterns enhance the latency of the mesh network by 16% and 14% in 16-core and 64-core systems, respectively. Finally, we discuss an adaptive data compression technique that builds a network-wide frequent value pattern map and reduces the packet size. In two examined multi-core systems, cache traffic has 69% compressibility and shows high value sharing among flows. Compression-enabled NoC improves the latency by up to 63% and saves energy consumption by up to 12%

Geographic Accessibility Analysis - Methods and Application

Geographic accessibility to services is important. Having a grocery store and a school nearby are important living conditions and having a rescue station close by could be a life-saver. Costs for transportation are high and are predicted to increase, new environmental demands are being imposed on transportation and rationalizations are centralizing public and commercial services. These facts make monitoring and planning accessibility increasingly important. Efficient computer systems for accessibility monitoring and planning could be used to improve accessibility to services. The aim of this study is to establish such efficient methods for geographic accessibility analysis and test them in computer applications. This was performed by studying effective ways of structuring data, algorithms for network searches and implementing these theories in test benches and application prototypes. Geographic accessibility to services is essential, especially when long distances must be covered, as in rural areas. The Swedish National Rural Development Agency (SNRDA) analyses accessibility to services from a national perspective, with the focus on rural areas. This is done using a computer model that is implemented in a Geographical Information System (GIS). This study investigates the foundations of the representation of road networks, connecting points to a network and accessibility studies through network searches. The results of this dissertation are meant to be used to develop the next generation of the system. Three papers are presented in this dissertation. The first deals with an evaluation of an existing accessibility analysis system at the Swedish National Rural Development Agency. The focus of the study was to identify performance bottlenecks in the SNRDA’s accessibility system and the problem areas that were found would then guide further research. One of the bottlenecks found in the study was the process of connecting points to large networks. This is investigated in the second paper and suggestions for solutions of the problem are presented. The third study is an applied study for planning accessibility to rescue services. This study concentrates on an application prototype called the Rescue Unit Planner (RUP) used for planning accessibility for non-stationary rescue units. The conclusions of this dissertation are that it is possible to build more efficient systems to perform accessibility analysis. The studies in this dissertation will support the further development of the SNRDA accessibility analysis system, which also was the overall goal