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Unformatted text preview: 1028 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 17, NO. 8, AUGUST 2007 A Network-Aware Approach for Video and Metadata Streaming Aravindan Raghuveer , Member, IEEE , Ewa Kusmierek, and David. H. C. Du , Fellow, IEEE Abstract Providing quality of service (QoS) for Internet-based video streaming applications requires the server and/or client to be network-aware and adaptive. We present a dynamic rate and quality adaptation algorithm where the server varies its sending rate (without varying the quality level) to adapt to the network and client conditions and only as a last resort, does quality adaptation. We place the adaptation logic at the client since it has better knowledge about both the demand (buffer conditions, variable bit-rate requirements) and supply (network conditions). Our approach is unique because the servers sending rate is calculated based on the clients varying demand (consumption rate) and the network status. Also, we do not model the network as a black-box but instead augment endpoint observations with a feedback from the network to represent its status more precisely. To make an informed adaptation decision, the client requires sizes of all frames in the variable bit rate video. But the overhead involved in sending this metadata is significant. So we propose a lossy com- pression technique to reduce the amount of control information and consequently the overhead. We also present a scheduling algorithm, Dynamic Scheduling Algorithm for Reduced Trace delivery (DART), to deliver the compressed control information to the client. This algorithm can be used to deliver any form of metadata (like subtitles, alerts, etc.), especially in applications like IP-TV. Simulations show that the proposed techniques can significantly improve user perceived QoS when compared to other popular adaptation methods. Index Terms IP-TV, metadata delivery, rate adaptation, QoS, trace compression, underflow curve. I. INTRODUCTION I NTERNET-BASED video streaming applications like IP-TV, video-conferencing, video classrooms, etc., are gaining increased popularity and are being widely deployed , . In these applications, the server transfers the requested audiovisual content to the client as a continuous stream and the client consumes the data as it arrives. Such multimedia applica- tions have stringent timing requirements for data consumption. The client can use a media unit only if it is delivered on time . This requirement imposes bandwidth, delay and loss demands on the underlying network that is responsible for delivering the data. But in a best effort network like the Internet, network parameters such as delay and bandwidth vary unpredictably providing no guarantee on timely delivery. This mismatch Manuscript received April 11, 2006; revised September 26, 2006 and January 17, 2007. This paper was recommended by Associate Editor T. Nguyen....
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