| Multimedia communication relies on a number of recent technologies advances, including compression, high speed networking, fast processing, and low cost storage. This dissertation proposes new solutions to three challenging problems of compressed video transmission: (1) bandwidth limitation, (2) channel errors and (3) multimedia security. The analytical results reported here are supported by simulation studies of actual video data.; We investigate the problem of using video transcoding for bandwidth adaptation. An analytic model is proposed to quantify the distortion introduced by the various steps in transcoding. The model can be used to compare the performance of different approaches to transcoding, allowing a designer to select the optimal among candidate methods. We then focus on reduced-resolution transcoding of compressed video bitstreams. The drift error is analyzed to provide a measure of degradation. Based on this analysis, new approaches and architectures are proposed to overcome the drift errors.; A new error resilient video coding approach is proposed to combat burst packet losses for video transmission over Internet and/or wireless links. A new block re-ordering scheme is proposed to isolate erroneous blocks caused by such packet losses. Unequal error protection using data hiding is used for additional protection of motion vectors.; A new system for video authentication is proposed. The system is based on a new classification of video tampering. A comparison of two basic authentication approaches, fragile watermarking and digital signature, is made and the possible combination of them is discussed. We also address the issues of “mutual watermarking” to authenticate multimedia data consisting of a mixture of video, audio and text data.; New approaches are proposed to use data hiding in multimedia communication to convey side information for additional functionalities or for better performance. |
