Efficient Code Synthesis from Extended Dataflow Graphs for Multimedia Applications

Department of Computer Science and Engineering
Seoul National University

Monday, January 28th, 6:30 PM, ENS 116

sha@iris.snu.ac.kr

Abstract

As system complexity increases and fast design turn-around time becomes important, automatic code synthesis from dataflow program graphs is a promising high level design methodology for rapid prototyping of complicated multimedia embedded applications. Memory efficient code synthesis from dataflow models has been an active research subject to reduce the gap in terms of memory requirements between the synthesized code and the hand-optimized code. Composite data types, such as video frame or network packet, are used extensively in recent networked multimedia applications, and become the major consumer of scarce memory resource. However, existent dataflow models have inherent difficulty of efficiently expressing the mixture of a composite data type and its constituents: for example, a video frame and macro blocks. A video frame is regarded as a unit of data sample in integer rate dataflow graphs, and should be broken down into multiple macro blocks, explicitly consuming extra memory space. In the proposed FRDF (Fractional Rate Data Flow) model, a constituent data type is considered as a fraction of the composite data type. Thus no explicit data type conversion is needed. Another extension, called synchronous piggybacked dataflow, is also proposed to accommodate global states in dataflow model without any side effect. In the synthesized code, global states are mapped to global data structures that many blocks can refer to. Finally, a new buffer sharing technique for structured data will be explained. In this talk, we will show that the series of techniques can successfully reduce the gap between the automatically synthesized code and the manually optimized code in terms of memory requirement.

Biography

Soonhoi Ha is currently an associate professor in the School of Computer Science and Engineering at Seoul National University since 1994. From 1993 to 1994, he worked for Hyundai Electronics Industries Corporation. He received his Bachelors (1985) and Masters (1987) in Electronics Engineering from Seoul National University, and PhD (1992) degrees in Electrical Engineering and Computer Science from University of California, Berkeley. He has worked on Ptolemy project. His research interests include hardware-software codesign, design methodology for embedded systems, and PC clusters. He is a member of ACM and the IEEE Computer Society.

A list of Telecommunications and Signal Processing Seminars is available at from the ECE department Web pages under "Seminars". The Web address for the Telecommunications and Signal Processing Seminars is http://signal.ece.utexas.edu/seminars