UBC Theses and Dissertations
Joint MPEG-2/H.264 scalable coding and enhancements to H.264 intra-mode prediction Storey, Duane Thomas
In this thesis, several enhancements and optimizations related to H. 264, the latest and most advanced video standard, are explored. The first part of this work involves the investigation of a new spatial scalability scheme involving MPEG-2 as a base-layer and H.264 as a spatial enhancement-layer. This scheme does not involve any bitstream modifications, and can be configured using off-the-shelf components. While simplistic, this scheme results in bitrate reductions for the tested CIF sequences of approximately 50% (depending on the quality of the base-layer) and bitrate reductions on the order of 20% for high-definition 720p imagery. An alternate scheme is also proposed that extends the H.264 bitstream syntax by adding a new 4x4 Intra-block prediction mode. For Intra-frames, bitrate reductions on the order of 25% are possible depending on the quality of the base-layer. Since this scheme can also choose to ignore distorted base-layer blocks, it is not subject to the large bit-penalty associated with low-bitrate base-layer sequences demonstrated using the first proposed scheme. Finally, a modified Intra-mode prediction scheme is proposed for H.264 that involves forming a real-time estimate of the joint probability distribution functions for the Intra prediction modes. Using these distributions, it is possible to obtain an increase in prediction accuracy of approximately 50% over the default H.264 prediction method.
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