Jason J. Yao

Design and Evaluation of a P2P IPTV System for Heterogeneous Networks

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.

A Collaborative Transcoding Strategy for Live Broadcasting Over Peer-to-Peer IPTV Networks

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.

IP datacasting and channel error handling with DVB-H

DVB-H is a terrestrial digital TV standard which consumes less power and allow user to move freely when receiving signals. Its deployment also signifies the convergence between broadcast network and data networks as both video signals and other data programs are transmitted in a shared media. In this paper we discuss the channel error problems under different scenarios of this convergence. Partial solutions, such as enhanced forward error correction were provided by the standard but other aspects still need further exploration. We present some early results and discuss possible directions in the future.

Robust Video Streaming over Power Lines

The upcoming HomePlug AV standard enables power line communication (PLC) networks to transmit high quality video streams applicable for various video on demand and video relay services in digital homes. However, video streaming over power lines is sensitive to the interference caused by electrical appliances and to the degradation of quality of service (QoS) caused by the increase of transmission distance. In this paper, we evaluate the performance of power line communications for video streaming under various conditions. We also propose a new multiple-description based video coding (MDC) technique for robust video streaming over power lines. This technique divides the video into an even-frame stream and an odd-frame stream in the server. Each stream is composed of two substreams, one at full resolution and the other at quarter resolution. The four substreams are encoded independently and transmitted in an interleaving manner. If packet losses occur in one substream, the decoder can compensate for the lost video by making use of the other substreams so as to maintain the output video quality

H.264/AVC-based multiple description video coding using dynamic slice groups

In this paper, an H.264/AVC-based multiple description video coding scheme is proposed. It utilizes the advanced video coding tools and features provided in H.264/AVC to introduce redundancy into descriptions. Two independently decodable descriptions are generated, each consisting of two slice groups. One of them, called main slice group (MSG), is encoded normally as main information. The other one, called side slice group (SSG), is encoded with fewer bits as redundancy information 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 is superior to previous slice group based multiple description coding (MDC) schemes in terms of the rate-distortion (R-D) performance.

H.264/AVC-Based Multiple Description Coding Scheme

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.

Complexity-aware live streaming system

The number of client requests that a streaming server can handle is limited by both its computational resources and available bandwidth. While bandwidth capacity is critical for most streaming applications, computational resources for a server encoding live videos often become a critical factor as well. In order to serve more client requests or provide higher quality for high priority clients, it is desirable to allocate and adjust the computational resources on a per channel basis. In this paper, we proposed a complexity-aware live video streaming server system that manages the computational resources dynamically. In the proposed system, input videos are encoded with different quality levels based on their priorities and available computational resources. The computational resources for each encoder are adaptively allocated to match the time constraints. The seven quality levels defined in the XviD MPEG-4 encoder are used in our experiments. The results show that the new design is able to maximize the resource utilization by maintaining the highest priority channels quality while providing the other channels with best-effort quality.

A complexity-aware video adaptation mechanism for live streaming systems

The paradigm shift of network design from performance-centric to constraint-centric has called for new signal processing techniques to deal with various aspects of resource-constrained communication and networking. In this paper, we consider the computational constraints of a multimedia communication system and propose a video adaptation mechanism for live video streaming of multiple channels. The video adaptation mechanism includes three salient features. First, it adjusts the computational resource of the streaming server block by block to provide a fine control of the encoding complexity. Second, as far as we know, it is the first mechanism to allocate the computational resource to multiple channels. Third, it utilizes a complexity-distortion model to determine the optimal coding parameter values to achieve global optimization. These techniques constitute the basic building blocks for a successful application of wireless and Internet video to digital home, surveillance, IPTV, and online games.

DFEC: Dynamic Forward Error Control for DVB-H

DVB-H is a terrestrial digital TV standard that allows user to move freely when receiving signals. Additional Reed-Solomon codes are also included as an option to cope with higher channel error rate in mobile environment. However, it is designed with fix-valued link layer parameters, such as coding rates and error rates. In mobile networks, channel conditions change from time to time, thus code rates that behave well in one case may become inadequate in another. On the other hand, to implement static and highly protective codes results in low throughput. In this paper, we propose dynamic forward error control scheme (DFEC) that adapts to varying channel conditions. Depending on the content carried, DFEC provides different schemes for more efficient utilization of channel capacities. Simulations show that it achieves a better throughput, which could also translate to more power saving for the system

A Scalable Peer-to-Peer IPTV System

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.