Adaptive resynchronization approach for scalable video over wireless channel

Scalable video coding technique is developed to provide a full scalability including temporal, spatial and quality scalability. The compressed bitstream can be separated into base layer and enhancement layers, where the base layer is usually small and of high importance. Error-free transmission could be realized for the base layer through high-priority protection. Therefore, the overall quality greatly depends on the enhancement layers. In this paper, we propose an adaptive resynchronization method to achieve a robust transmission of the enhancement layer information. The scheme firstly groups the enhancement layer bitstream of a group of pictures (GOPs) into a set of units with different temporal levels and quality levels. We measure the importance of each unit and organize them into hierarchical units from the most important unit to the least important one. The overall distortion is formulated and a local hill-climbing algorithm is designed to optimally insert different amount of resynchronization markers to different unit considering the time-varying channel conditions and the significance of each unit. It is shown from experimental results that the proposed method can perform a graceful degradation under a variety of error conditions and shows advantages over conventional method. The improvement is up to 1 dB. We also conduct the experiments to demonstrate that the resynchronization method can also be employed together with other error resilient methods to further improve the quality of the decoded video.