Video Compression Algorithms and Related Transport Protocols for Real Time, Unicast and Multicast Video over internet

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Supporting low latency video communication over the Internet is an important yet challenging task. A few possible applications include video conferencing, tele-medicine, and interactive access to pre-recorded videos stored in remote databases. There are two main requirements for internet video communication: (1) bandwidth scalability; (2) error-resilient. Lack of bandwidth scalability results in non-adaptive streams with two sets of disadvantages. First, it leads to congestion collapse when the aggregate bandwidthof the video traffic exceeds network capacity. Second, it competes unfairly with other adaptive traffic, such as TCP, which reduces transmission rate in face of network congestion. Lack of error resilience results in error propagation, and hence widely varying video quality as a function of time. Current approaches to mitigate the effects of error propagation include error control mechanisms at the transport level. This typically takes the form of retransmissions or forward error correction (FEC). Retransmission based error control methods often fail to be real-time, particularly when round-trip propagation delay is large.FEC schemes on the other hand, are often ineffective when losses are bursty.The main goal of this proposal is to investigate video compression techniques and transport protocols needed for real time delivery of unicast and multicast video over best effort networks such as the internet. Our approach for the unicast case is to combine a novel compression method that is error resilient and bandwidth scalable with a low-delay TCP-friendly transport protocol. Specifically, compressed video is packetized into individually decodable packets of equal expected visual importance. Consequently, relatively constant video quality can be achieved at the receiver under lossy conditions. Furthermore, the packets can be truncated to instantaneously meet the time varying bandwidth imposed by a TCP-friendly transport protocol. As a result,adaptive flows that are friendly to other Internet traffic are produced. Actual Internet experiments together with simulations are used to evaluate the performance of the compression, transport, and the combined schemes.Our approach to multicast video transmission is to combine bandwidth scalable video compression scheme with hierarchical FEC. By hierarchical FEC, we mean the production of embedded FEC or redundancystreams, each of which belongs to a different multicast group. This way, subscribing to more groups corresponds to higher level of protection, but larger delays. There are two advantages to this approach. First, each receiver can independently adjust the desired level of protection based on past reception statistics and loss characteristics. This receiver-driven approach to FEC is more flexible than most existing FEC schemes for multicast where the source determines a set of redundancy packets which are then multicast to every recipient. Second, each receiver will subscribe to only as many redundancy layers as necessary, reducing overall bandwidth utilization. Furthermore, the hierarchical nature of the FEC layers ensuresminimum network utilization through sharing of common redundancy streams. Actual internet experiments will be done to examine the effectiveness of our approach.