MPEG-2 in a Stream Programming Language

Abstract

Image and video codecs are prevalent in multimedia applications, ranging from embedded systems, to desktop computers, to high-end servers such as HDTV editing consoles. It is not uncommon however for developers create (from scratch) and customize their codec implementations for each of the architecture targets they intend their coders and decoders to run on. This practice is time consuming and error prone, leading to code that is not malleable or portable. In this paper we describe an implementation of the MPEG-2 codec using the StreamIt programming language. StreamIt is an architecture independent stream language that aims to improve programmer productivity, while concomitantly exposing the inherent parallelism and communication topology of the application. We describe why MPEG is a good match for the streaming programming model, and illustrate the malleability of the implementation using a simple modification to the decoder to support alternate color compression formats. StreamIt allows for modular application development, which also reduces the complexity of the debugging process since stream components can be verified independently. This in turn leads to greater programmer productivity. We implement a fully functional MPEG-2 decoder in StreamIt. The decoder was developed in eight weeks by a single student programmer who did not have any prior experience with MPEG or other video codecs. Many of the MPEG-2 components were subsequently reused to assemble a JPEG codec.