Date of Award

2002

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Computer Science

Abstract

The goal of this study was to conduct multiple regression analyses of selected variables effecting the transmission of video over Internet Protocol (IP) networks, utilizing data from Peak Signal-to-Noise Ratio (PSNR) and Picture Quality Rating (PQR) measurement metrics. The variables selected for this research were congestion-specific in nature and multiple regression analyses were performed to identify the amount of variance in video signal quality attributable to their combined effects. The foundational research hypothesis constructed for this study proposed that increases in CODEC bit rates and network bandwidth would have no significant effect on the PSNR and PQR levels of transmitted video sequences that were devoid of packet loss, packet delay, or jitter. The packet-specific impairments and limitations on bandwidth were introduced into the test network by way of commercial off-the-shelf (COTS) impairment emulation software, and the CODEC bit rates were controlled at the device level. The testing outcomes indicated a high level of significance in the variance of the CODEC bit rate and network bandwidth for non-impaired video sequences to the PSNR and PQR levels achieved when bit rate and bandwidth were maximized. However, only a moderately significant amount of variance in the overall video quality was attributable to the combined effects of packet loss (drop), packet delay (latency), jitter, and the selected combinations of CODEC bit rate and bandwidth availability. The results of this research validated that with or without the presence of selected packet-specific impairments, increases in bandwidth and CODEC bit rates do in fact improve the quality of video transmitted over IP networks. For technology managers, this study highlights the importance of recognizing video quality degradation as a by-product of packet-specific impairments and network traffic dynamics. The accompanying documentation includes a video quality improvement decision flowchart emphasizing the need for a continuous process of output monitoring and quality improvement.

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