Systematic Lossy Error Protection of Video Signals a Dissertation Submitted to the Department of Electrical Engineering and the Committee on Graduate Studies of Stanford University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

This thesis addresses the problem of error-resilient video transmission. In most video transmission applications, a video signal is compressed, packetized and transmitted over an error-prone channel. Owing to multipath fading on wireless channels and/or congestion in the Internet, some video packets are lost or arrive in error. When feedback is unavailable or limited, this problem is traditionally solved by applying a Forward Error Correction (FEC) code and transmitting a suitable amount of redundant (parity) information along with the video packets. However, the number of parity symbols are insufficient for error correction at high error probabilities, and this results in a precipitous drop in video quality, which is commonly referred to as the “cliff” effect. This thesis describes and analyzes a scheme which mitigates the FEC cliff and obtains graceful degradation of video quality at the receiver by leveraging distributed source coding ideas for error resilience. The Systematic Lossy Error Protection (SLEP) scheme is based on the principle of systematic lossy source/channel coding. The systematic portion of the transmission consists of a compressed video signal which is sent to the decoder without channel coding. For error resilience, a supplementary bit stream generated by Wyner-Ziv encoding of the video signal is also transmitted to the receiver. The Wyner-Ziv bit stream allows the decoding of a coarsely quantized redundant video description, which can be used in lieu of the lost or error-prone portions of the systematic signal. The resulting error protection scheme is based on a flexible tradeoff between the coarseness (quality) of the redundant video description and the error robustness provided by that description.