Meng-Ting Lu

Smooth Control of Adaptive Media Playout for Video Streaming

Client-side data buffering is a common technique to deal with media playout interruptions of streaming video caused by network jitters and packet losses of best-effort networks. However, stronger playout interruption protection inevitably amounts to larger data buffering and results in more memory requirements and longer playout delay. Adaptive media playout (AMP), also a client-side technique, can reduce the buffer requirement and avoid buffer outage but at the expense of visual quality degradation because of the fluctuation of playout speed. In this paper, we propose a novel AMP scheme to keep the video playout as smooth as possible while adapting to the channel condition. The triggering of the playout control is based on buffer variation rather than buffer fullness. Experimental results show that our AMP scheme surpasses conventional schemes in unfriendly network conditions. Unlike previous schemes that are tuned for a specific range of packet loss and network instability, the proposed AMP scheme maintains consistent performance across a wide range of network conditions.

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.

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

Smooth Playout Control for Video Streaming over Error-Prone Channels

The quality of media streaming over best-effort networks suffers from network delays and packet losses. The latter is more profound for wireless video. To enhance the QoS of streaming services, adaptive media playout (AMP) has been developed to adjust the playout interval. With AMP, the risk of delay and buffer underflow is reduced. However, the smoothness of playback is not guaranteed. In this paper, we propose a novel AMP control that enables smooth playout and meanwhile maintains reliable visual quality. Our AMP control adjusts the playout interval based on an estimation of channel quality, so it is more adaptive than conventional AMP controls that are based on buffer fullness. Experimental results are provided to justify our approach. Even at 20% packet loss rate, the proposed AMP control is still able to provide smooth and reliable playback

Fast multi-frame motion estimation for H.264 and its applications to complexity-aware streaming

JVT/H.264 achieves higher compression efficiency than previous video coding standards such as MPEG4 and H.263. However, this comes at the cost of increased complexity due to the use of variable block-size, multiple reference frame motion compensation, and other advanced coding algorithms. In this paper, we present a fast motion estimation algorithm. This algorithm is based on an adaptive search strategy and a flexible multi-frame search scheme. Compared to the H.264 reference software JM 8.5, this algorithm achieves, on average, a 522% reduction of encoding time, with negligible PSNR drop and bit-rate increase. Performance comparison results are described, and the architecture of a complexity-aware streaming server that applies the algorithm to provide differentiated services is discussed.

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.

DSP implementation of digital image stabilizer

A digital image stabilization system compensates the image movement caused by hand jiggle for the image sequence captured by a hand-held video camera. In this paper, a simplified stabilization algorithm based on our previous work is presented. The algorithm performs block-based motion estimation on 16 local 16/spl times/16 blocks and uses a median filter to estimate the global motion. It reduces the complexity by confining the motion estimation to a small number of blocks of the image. This greatly facilitates the implementation of the algorithm on BF561, a DSP processor of analog device. Details of the DSP implementation are described.

Video Streaming Over In-Home Power Line Networks

The deployment of power line communication technology for broadband video streaming remains a challenge because power lines are not originally designed for signal transmission. Scalable video is a viable approach that can cope with the bandwidth fluctuation of power line communication networks provided that the bandwidth information is available. In this paper we first investigate how the interference caused by electrical appliances or power supplies affects the power line channel bandwidth and packet transmission. Then we take the obtained characteristics of in-home power line network into account in the design of a simple but effective heuristic-based application-layer bandwidth estimation scheme, for which the cutoff rate is estimated from the packet size and the physical-layer data rates. Experimental results show that the proposed approach can effectively combat the noise interference and deliver robust video streaming over power line.

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.

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.