Abstract:
Successful video communication over wireless channels is one of the most technically challenging problems in multimedia communications. The inherent vulnerability of compressed video to transmission errors and the time varying and fading environments of the wireless channel combined with network and application constrains presents some major technological issues that needs to be addressed. To improve the error resiliency and efficiency of transmitting video over wireless channels. Several techniques are developed that contribute to better utilize the error resilient features available in H.264 and propose enhancements to the frame layer rate control. Firstly, new techniques on how to use explicit Flexible Macroblock Ordering (FMO) more effectively in wireless video ransmission by using combined spatial and temporal indicators of macroblock (MB) importance to generate slice group maps for H.264. Secondly, an improved sorting algorithm that classifies macroblocks into different slice groups for FMO in H.264 that further improves the use of explicit FMO. Thirdly, enhancements to the H.264 frame layer rate control is proposed, that takes into consideration the effects of using FMO for video transmission, to better manage bit allocation and improve coding efficiency. We propose a new header bits model, an enhanced frame complexity measure, a bit allocation and a quantization parameter (QP) adjustment scheme. Lastly, a framework for adaptive FMO selection scheme based on feedback information is presented. In summary, in this dissertation we propose the framework of using explicit FMO, rate control and feedback information for wireless video transmission. Experimental results show that the proposed techniques are effective in improving the video quality especially for complex video sequences and at low-bit rates.
