Improvements for hybrid and three dimensional wavelet based video coders
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Scalability is an important desirable property of video codecs. The popularity of multimedia applications demands support for different receivers that operate at different bit rates, resolution and complexity. This mandates the need for a scalable video coder with high compression efficiency. Another major requirement is the end-to-end delay for compression and decompression of video. The delay introduced by the coding operation should be less for applications like conversational services, tele-conferencing and video monitoring systems. Wavelet based coding has received considerable attention in the past few years and has the very best coding efficiency in image coders. Wavelet transform of a signal provides a multiresolution/multifrequency representation in both the spatial and frequency domains which makes it an ideal candidate for image and video coding. Wavelet based coding is now becoming a powerful coding option for video both in traditional predictive feedback (closed loop) schemes and in three-dimensional (open loop) methods. Based on previous research in the area of traditional hybrid coding and wavelet-based video coding, we explored the various challenges faced by the hybrid model and the closed loop coding schemes under various scenarios. The goal of this work is to design efficient and innovative solutions to overcome the challenges faced by wavelet based video coding. Three major challenges: drift control, end-to-end delay and quality fluctuation has been addressed and solutions have been developed. The following topics were explored in detail: (1) Controlling drift in Type I (closed loop) Video coding system. (2) Reducing encoding and decoding delay in Type II (open loop) Video Coding system. (3) Controlling erratic variation in video quality in Type II Video coding system. A detail analysis, mathematical solutions are provided on these topics and conclusions are drawn using experimental results.