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UBC Theses and Dissertations

Error reduction and control algorithms for MPEG-2 video transport over IP networks Lam, Ernest

Abstract

MPEG-2 multimedia transmission over IP networks is becoming a viable solution for high quality multimedia delivery. The MPEG-2 coding algorithm is very sensitive to channel disturbances because a single bit error in the video bitstream can cause serious video quality degradation due to error propagation. For an IP network, packet loss is the major source of errors. According to the encapsulation of the MPEG-2 data, a packet loss can cause the loss of a whole picture. As a result, the impact of a single packet loss is much more serious than that of the traditional single bit error effect. In this project, an IP testbed is set up to study the packet loss effect on the MPEG-2 video stream. By analyzing this packet loss effect and the prioritized nature of the MPEG-2 data structure, several error reduction algorithms are proposed and implemented into this testbed. Firstly, the probability of losing packets and the importance of different types of MPEG-2 data are analyzed, and the error tolerance of different MPEG-2 data is derived. Given the results, three different duplication of picture header algorithms are proposed and implemented. Besides, two error concealment algorithms are also proposed: picture replacement and slice replacement. Both subjective (MOS) and objective (PSNR) measurements are taken and analyzed. Analysis of the pros and cons of the above algorithms leads to the introduction of a hybrid error reduction algorithm. This hybrid error reduction algorithm improves the video quality in an acceptable way by minimizing the picture hesitation, flickering, motion blurring and block artifacts caused by the IP packet loss.

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