272 research outputs found

    Automatic software synthesis of dataflow program: An MPEG-4 simple profile decoder case study

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    International audienceThe MPEG Reconfigurable Video Coding (RVC) framework is a new standard under development by MPEG that aims at providing a unified high-level specification of current MPEG video coding technologies. In this framework, a decoder is built as a configuration of video coding modules taken from the standard "MPEG toolbox library". The elements of the library are specified by a textual description that expresses the I/O behavior of each module and by a reference software written using the CAL Actor Language. A decoder configuration is written in an XML dialect by connecting a set of CAL modules. Code generators are fundamental supports that enable the direct transformation of a high level specification to efficient hardware and software implementations. This paper presents a synthesis tool that from a CAL dataflow program generates C code and an associated SystemC model. Experimental results of the RVC Expert's MPEG-4 Simple Profile decoder synthesis are reported. The generated code and the associated SystemC model are validated against the original CAL description which is simulated using the Open Dataflow environment

    Dataflow/Actor-Oriented language for the design of complex signal processing systems

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    International audienceSignal processing algorithms become more and more complex and the algorithm architecture adaptation and design processes cannot any longer rely only on the intuition of the designers to build efficient systems. Specific tools and methods are needed to cope with the increasing complexity of both algorithms and platforms. This paper presents a new framework which allows the specification, design, simulation and implementation of a system operating at a higher level of abstraction compared to current approaches. The framework is base on the usage of a new actor/dataflow oriented language called CAL. Such language has been specifically designed for modelling complex signal processing systems. CAL data flow models expose the intrinsic concurrency of the algorithms by employing the notions of actor programming and dataflow. Concurrency and parallelism are very important aspects of embedded system design as we enter in the multicore era. The design framework is composed by a simulation platform and by Cal2C and CAL2HDL code generators. This paper described in details the principles on which such code generators are based and shows how efficient software (C) and hardware (VHDL and Verilog) code can be generated by appropriate CAL models. Results on a real design case, a MPEG-4 Simple Profile decoder, show that systems obtained with the hardware code generator outperform the hand written VHDL version both in terms of performance and resource usage. Concerning the C code generator results, the results show that the synthesized C-software mapped on a SystemC scheduler platform, is much faster than the simulated CAL dataflow program and approaches handwritten C versions

    Software Code Generation for the RVC-CAL Language

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    International audienceThe MPEG Reconfigurable Video Coding (RVC) framework is a new standard under development by MPEG that aims at providing a unified high-level specification of current and future MPEG video coding technologies using dataflow models. In this framework, a decoder is built as a configuration of video coding modules taken from the standard MPEG toolbox library or proprietary libraries. The elements of the library are specified by a textual description that expresses the I/O behavior of each module and by a reference software written using a subset of the CAL Actor Language named RVC-CAL. A decoder configuration is written in an XML dialect by connecting a set of CAL modules. Code generators are fundamental supports that enable the direct transformation of a high level specification to efficient hardware and software implementations. This paper presents a synthesis tool that from a CAL dataflow program generates C code and an associated SystemC model. The generated code is validated against the original CAL description simulated using the Open Dataflow environment. Experimental results of the translation of two descriptions of an MPEG-4 Simple Profile decoder with different granularities are shown and discussed

    Bridging MoCs in SystemC specifications of heterogeneous systems

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    In order to get an efficient specification and simulation of a heterogeneous system, the choice of an appropriate model of computation (MoC) for each system part is essential. The choice depends on the design domain (e.g., analogue or digital), and the suitable abstraction level used to specify and analyse the aspects considered to be important in each system part. In practice, MoC choice is implicitly made by selecting a suitable language and a simulation tool for each system part. This approach requires the connection of different languages and simulation tools when the specification and simulation of the system are considered as a whole. SystemC is able to support a more unified specification methodology and simulation environment for heterogeneous system, since it is extensible by libraries that support additional MoCs. A major requisite of these libraries is to provide means to connect system parts which are specified using different MoCs. However, these connection means usually do not provide enough flexibility to select and tune the right conversion semantic in amixed-level specification, simulation, and refinement process. In this article, converter channels, a flexible approach for MoC connection within a SystemC environment consisting of three extensions, namely, SystemC-AMS, HetSC, and OSSS+R, are presented.This work is supported by the FP6-2005-IST-5 European project

    A Networked Dataflow Simulation Environment for Signal Processing and Data Mining Applications

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    In networked signal processing systems, dataflow graphs can be used to describe the processing on individual network nodes. However, to analyze the correctness and performance of these systems, designers must understand the interactions across these individual "node-level'' dataflow graphs --- as they communicate across the network --- in addition to the characteristics of the individual graphs. In this thesis, we present a novel simulation environment, called the NS-2 -- TDIF SIMulation environment (NT-SIM). NT-SIM provides integrated co-simulation of networked systems and combines the network analysis capabilities provided by the Network Simulator (ns) with the scheduling capabilities of a dataflow-based framework, thereby providing novel features for more comprehensive simulation of networked signal processing systems. Through a novel integration of advanced tools for network and dataflow graph simulation, our NT-SIM environment allows comprehensive simulation and analysis of networked systems. We present two case studies that concretely demonstrate the utility of NT-SIM in the contexts of a heterogeneous signal processing and data mining system design

    A model-based approach for the specification and refinement of streaming applications

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    Embedded systems can be found in a wide range of applications. Depending on the application, embedded systems must meet a wide range of constraints. Thus, designing and programming embedded systems is a challenging task. Here, model-based design flows can be a solution. This thesis proposes novel approaches for the specification and refinement of streaming applications. To this end, it focuses on dataflow models. As key result, the proposed dataflow model provides for a seamless model-based design flow from system level to the instruction/logic level for a wide range of streaming applications

    Reconfigurable video coding: a stream programming approach to the specification of new video coding standards

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    International audienceCurrent video coding standards, and their reference implementations, are architected as large monolithic and sequential algorithms, in spite of the considerable overlap of functionality between standards, and the fact that they are frequently implemented on highly parallel computing platforms. The former leads to unnecessary complexity in the standardization process, while the latter implies that implementations have to be rebuilt from the ground up to reflect the parallel nature of the target. The upcoming Reconfigurable Video Coding (RVC) standard currently developed at MPEG attempts to address these issues by building a framework that supports the construction of video standards as libraries of coding tools. These libraries can be incrementally updated and extended, and the tools in them can be aggregated to form complete codecs using a streaming (or dataflow) programming model, which preserves the inherent parallelism of the coding algorithm. This paper presents the RVC framework and its underlying data flow programming model, along with the tool support and initial results

    On mixed abstraction, languages and simulation approach to refinement with SystemC AMS

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    Executable specifications and simulations arecornerstone to system design flows. Complex mixed signalembedded systems can be specified with SystemC AMSwhich supports abstraction and extensible models of computation. The language contains semantics for moduleconnections and synchronization required in analog anddigital interaction. Through the synchronization layer, user defined models of computation, solvers and simulators can be unified in the SystemC AMS simulator for achieving low level abstraction and model refinement. These improvements assist in amplifying model aspects and their contribution to the overall system behavior. This work presents cosimulating refined models with timed data flow paradigm of SystemC AMS. The methodology uses Cbased interaction between simulators. An RTL model ofdata encryption standard is demonstrated as an example.The methodology is flexible and can be applied in earlydesign decision trade off, architecture experimentation and particularly for model refinement and critical behavior analysis

    Overview of the MPEG Reconfigurable Video Coding Framework

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    International audienceVideo coding technology in the last 20 years has evolved producing a variety of different and complex algorithms and coding standards. So far the specification of such standards, and of the algorithms that build them, has been done case by case providing monolithic textual and reference software specifications in different forms and programming languages. However, very little attention has been given to provide a specification formalism that explicitly presents common components between standards, and the incremental modifications of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO standard currently under its final stage of standardization, aiming at providing video codec specifications at the level of library components instead of monolithic algorithms. The new concept is to be able to specify a decoder of an existing standard or a completely new configuration that may better satisfy application-specific constraints by selecting standard components from a library of standard coding algorithms. The possibility of dynamic configuration and reconfiguration of codecs also requires new methodologies and new tools for describing the new bitstream syntaxes and the parsers of such new codecs. The RVC framework is based on the usage of a new actor/ dataflow oriented language called CAL for the specification of the standard library and instantiation of the RVC decoder model. This language has been specifically designed for modeling complex signal processing systems. CAL dataflow models expose the intrinsic concurrency of the algorithms by employing the notions of actor programming and dataflow. The paper gives an overview of the concepts and technologies building the standard RVC framework and the non standard tools supporting the RVC model from the instantiation and simulation of the CAL model to software and/or hardware code synthesis
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