The main objective of this article is to provide an overview of P2P based Video-on-Demand and live streaming services. The article starts with an introduction to media streaming and its simplified architecture. Various solutions offering video streaming in the context of widespread usage of Internet are discussed. This is followed by a short introduction to P2P networks and its applications. A broad discussion on various P2P streaming schemes and P2P streaming applications are the main focus of this chapter. Finally, the security issues and solutions for P2P video streaming are discussed briefly.Typically, for streaming video, congestion control takes the form of rate control. Rate control attempts to minimize the possibility of network congestion by matching the rate of the video stream to the available network bandwidth. Based on the place where rate control is taken in the system, rate control can be categorized into three types: sourcebased, receiver-based and hybrid-based. With the source-based rate control, only the sender (server) is responsible for adapting the transmission rate. In contrast, the receiving rate of the streams is regulated by the client in the receiverbased method. Hybrid-based rate control employs the aforementioned schemes at the same time, i.e. both the server and client are needed to participant in the rate control. Typically, the source-based scheme is used in either unicast or multicast environment while the receiver-based method is deployed in multicast only [6].The function of error control is to improve video presentation quality in the presence of packet loss. Error control mechanisms include Forward Error Correction (FEC), retransmission, error-resilient encoding and error concealment. With FEC scheme, the received packets at the receiver end are FEC decoded and unpacked, and the resulting bit stream is then input to the video decoder to reconstruct the original video. Error-resilient encoding is executed by the source to enhance robustness of compressed video before packet loss actually happens. Even when an image sample or a block of samples are missing due to transmission errors, the decoder can try to estimate them based on surrounding received samples, by making use of inherent correlation among spatially and temporally adjacent samples, such techniques arc known as error concealment techniques [14].
Media distribution services:After the adaptation by application-layer QoS control module, the transport protocols packetize the compressed bit-streams and send the video/audio packets to the Internet. Packets may be dropped or experience excessive delay inside the Internet due to congestion. In addition to the application-layer support, adequate network support is necessary to reduce transport delays and packet losses. The network support involves network filtering, application-level multicast and content replication (caching). Network filtering maximizes video quality during network congestion. The filter at the video server can adapt the rate of video streams according to the...