Synchronization control of coded video streams: Algorithms and implementation.

Abstract

In this thesis, we propose to blend the intra-media synchronization control of coded video streams with the decoding process. We present a client based application level buffer control scheme for coded video to maintain stream continuity, avoid data overflow and underflow conditions and compensate for possible clock drifts at the client. The control policy, referred to as the Predecoder Synchronization Controller (PSC), uses buffer occupancy as its main control parameter. Based on high and low buffer occupancy thresholds, overflow threats and starvation threats are detected. Time contraction (selective frame drop) and expansion concepts (selective frame repeat) are used to prevent these data overflow and starvation threats to become real conditions, respectively. PSC algorithms are specified for both Motion JPEG and MPEG. In the case of starvation or overflow threats, the PSC was found to smoothen the stream, avoiding long frame freeze and abrupt scene change situations, by creating localized variations in the rate of displayed stream. A prototype implementation of both MJPEG and MPEG PSCs was also carried out. (Abstract shortened by UMI.)