Design of a transport coding scheme for high-quality video over ATM networks

Abstract

In this paper, we explore the design of forward error control (FEC)-based error concealment schemes for digital video transmission on ATM networks. In particular, we study the impact of code selection on the overall performance and provide a judicious code selection strategy. The use of FEC provides an active and powerful means of recovery from packet loss which is particularly useful when the encoded video material has high motion and scene changes. The best technique for applying FEC is to throttle the source coding rate so that the overall transmission rate after FEC application equals the original unprotected rate. However, the resulting performance then depends on the particular code selected. A well-chosen code provides good protection while allowing little sacrifice in quality and at the same time satisfies specified delay constraints. Our results show that a single code is generally insufficient to provide good performance under all operating conditions. However, a small group of codes can be preselected, using the efficient code-selection strategy described here, which will provide efficient and robust performance over a wide range of channel conditions. We show that this simple code selection strategy is sufficient to select codes judiciously for a wide range of operating conditions and constraints. Employing this selection strategy, we demonstrate that moderate length codes are sufficient to provide good performance while meeting the imposed delay constraint.