Real-time video transcoding that is often needed for robust video broadcasting over heterogeneous networks is not supported in most existing devices. To address this problem, we propose a collaborative strategy that leverages the peering architecture of peer-to-peer Internet protocol television networks and makes the computational resources of peers sharable. The video transcoding task is distributed among the peers and completed collaboratively. A prototype of the live video broadcasting system is evaluated over a 100-node testbed on the PlanetLab. The experimental results show that the proposed strategy works effectively even when the majority of the peers have limited computational resource and bandwidth.

HotStreaming is an overlay peer-to-peer (P2P) based IPTV system. It integrates the innovations in both overlay networking and video coding for optimal user experience. The HotStreaming system is composed of three key components: partnership formation, data request scheduling and multiple description coding (MDC). In the partnership formation component, we propose two policies to reduce the time of disconnection and the number of isolated peers. In the MDC component, we adopt MDC with spatial-temporal hybrid interpolation (MDC-STHI), which makes the peers in a P2P network to adjust the streaming traffic according to their bandwidth limitation and capability of devices. The experimental results show that the HotStreaming system improves the video quality over a lossy and dynamic networking environment.

A new multiple description coding (MDC) scheme is proposed in this paper. It utilizes the advanced video coding tools and features provided in H.264/AVC to introduce redundancy into descriptions. The proposed MDC scheme produces two descriptions, each consisting of two slice groups. One of them, called main slice group (MSG), is encoded in the normal way as main information. The other one, called side slice group (SSG), is encoded with fewer bits as redundancy by using larger quantization step sizes. Spatial and temporal correlations between neighboring macroblocks in video frames are exploited to achieve efficient redundancy coding. Experimental results show that the proposed MDC scheme achieves better rate-distortion (R-D) performance than previous slice-group based MDC schemes.

NTUStreaming is an overlay P2P-based IPTV system that integrates innovations in both overlay networking and video coding for optimal user experience. The system consists of three key components: partnership formation, robust video coding, and video segment request scheduling. For partnership formation, a graph construction mechanism TYPHOON based on epidemic algorithms is developed to reduce disconnect time and isolated peers. For robust video coding, a multiple description coding (MDC) scheme with spatial-temporal hybrid interpolation (STHI) is proposed to adjust streaming traffic according to the bandwidth and device capability of each peer. For request scheduling, an optimization algorithm is developed by taking the available bandwidth and the video segment type into account. Experimental results show that NTUStreaming is able to deliver optimal video quality in lossy and dynamic networking environments.