Research On Real-Time Video Transmission Over Networks

With the rapid growth of multimedia content in today's communication links, there is an increasing demand for video coding schemes and underlying transport that can provide acceptable quality of service to the end users. Due to the errors nature of channels and the error propagation property of compressed video, suitable source and channel coding schemes are required to handle such conditions.This dissertation deals with the issues of video coding and transmission over unreliable channels. Based on the video coding standards, such as MPEG-4 and H.26L, and networks protocols, we presented some schemes on error resilient video coding and transmission techniques.The main contribution includes:1. Presents an improved IP differentiated services (DiffServ) framework which is suitable for real-time video transmission. Especially, we investigate MPEG-4 video transmission. Based on the feature of MPEG-4 flow and the extent of network congestion, we propose a new DiffServ marking algorithm. In the border router, we propose a new scheduling algorithm, called the Bit-based Weight time Slot Compensate (BWSC) scheduling algorithm, which dynamically adjust the weighted quantum of service. Under the condition that network bandwidth can't guarantee the demand of MPEG-4 real-time transmission, the PSNR comparison of restored MPEG-4 video frame sequence verifys our method has much better performance than Best-effort network. End-to-end delay and delay jitter also meet the real-time transmission demand in the improved DiffServ network.2. Presents a modified version of the deficit round-robin (DRR) scheduling algorithm. The proposed scheduling scheme called Weighted Switch Deficit Round Robin (WSDRR) categorises the different frame types of compressed video which are handled in separate queues and prioritizes time-sensitive and visually important data. WSDRR also introduces an overdraft threshold that basically allows a packet to be scheduled even if its flow's deficit is not large enough in a given scheduling round. By numerical experiments, WSDRR achieves better delay and delay jitter performance than...