Contributions to coding techniques for wireless multimedia communication

Two coding techniques for efficient wireless multimedia communication are investigated in this dissertation: (i) an embedded space-tune coding (STC) technique for scalable video broadcast with a multiple-antenna system, and (ii) a fast motion mode selection and motion vector search technique for effective implementation of the emerging video coding standard H.264.; In the first part, an embedded STC method is proposed for the wireless broadcast application. We investigate embedded space-tune codes for layered media broadcast. In such a system, a transmitter sends out multi-layer source signals by encoding different layers with different space-time codes. Then, the receiver can retrieve a different amount of information depending on the number of antennas it has as well as the level of the receiving power. A receiving terminal with one antenna can decode only the base layer information with a low complexity decoder while a more advanced terminal with more antennas can retrieve more layers of information. We further consider the case where the channel state information (CSI) is unknown. We explore the embedded design with differential STC to enable layered media transmission. Issues of differential design are investigated. Both analytic and experimental results are reported.; In the second part of this dissertation, we propose a fast motion search algorithm for the H.264 encoder. One major contribution of the gain of H.264 comes from a very rich syntax for motion compensated prediction at the expense of a higher computational complexity. To be more specific, seven modes of different block sizes and shapes (i.e. 16 x 16, 16 x 8, 8 x 16, 8 x 8, 8 x 4, 4 x 8 and 4 x 4) are supported. To do full search over all modes requires an extremely large amount of computation. We propose a fast search algorithm for the variable block size motion estimation. The proposed algorithm includes multi-resolution motion search and a rate-distortion measure to set early-termination rules. By avoiding search through all block sizes, the amount of computation involved in the motion search can be substantially reduced. The proposed algorithm can achieve a speed-up factor up to 120 times when compared to the fastest full-search algorithm.