Assessing video content transmitted over networked content infrastructures becomes a fundamental requirement for
service providers. Previous research has shown that there is no direct correlation between traditional network QoS and
user perceived video quality. This paper presents a study investigating the impact of individual packet loss on four types
of H.264 main-profile encoded video streams. Four artifact factors to model the degree of artifacts in video frames are
defined. Further, the visibility of artifacts considering the video content characteristics, encoding scheme and error
concealment is investigated in conjunction with a user study. The individual and joint impacts of artifact factors are
explored on the test video sequences. From the results of user tests, the artifact factor-based assessment method shows
superiority over PSNR-based and network QoS based quality assessment.
The quality of service for latency dependent content, such as video streaming, largely depends on the distance and available bandwidth
between the consumer and the content. Poor provision of these qualities results in reduced user experience and increased overhead. To
alleviate this, many systems operate caching and replication, utilising dedicated resources to move the content closer to the consumer.
Latency-dependent content creates particular issues for community networks, which often display the property of strong internal
connectivity yet poor external connectivity. However, unlike traditional networks, communities often cannot deploy dedicated
infrastructure for both monetary and practical reasons. To address these issues, this paper proposes Corelli, a peer-to-peer replication
infrastructure designed for use in community networks. In Corelli, high capacity peers in communities autonomously build a
distributed cache to dynamically pre-fetch content early on in its popularity lifecycle. By exploiting the natural proximity of peers in
the community, users can gain extremely low latency access to content whilst reducing egress utilisation. Through simulation, it is
shown that Corelli considerably increases accessibility and improves performance for latency dependent content. Further, Corelli is
shown to offer adaptive and resilient mechanisms that ensure that it can respond to variations in churn, demand and popularity.
Several types of Content Distribution Networks are being deployed over the Internet today, based on different architectures to meet their requirements (e.g., scalability, efficiency and resiliency). Peer-to-Peer (P2P) based Content Distribution Networks are promising approaches that have several advantages. Structured P2P networks, for instance, take a proactive approach and provide efficient routing mechanisms. Nevertheless, their maintenance can increase considerably in highly dynamic P2P environments. In order to address this issue, a two-tier architecture that combines a structured overlay network with a clustering mechanism is suggested in a hybrid scheme. In this paper, we examine several sampling algorithms utilized in the aforementioned hybrid network that collect local information in order to apply a selective join procedure. The algorithms are based mostly on random walks inside the overlay network. The aim of the selective join procedure is to provide a well balanced and stable overlay infrastructure that can easily overcome the unreliable behavior of the autonomous peers that constitute the network. The sampling algorithms are evaluated using simulation experiments where several properties related to the graph structure are revealed.
Conference Committee Involvement (4)
Multimedia Computing and Networking 2009
19 January 2009 | San Jose, California, United States
Multimedia Computing and Networking 2008
30 January 2008 | San Jose, California, United States
Multimedia Computing and Networking 2007
31 January 2007 | San Jose, CA, United States
Multimedia Computing and Networking 2006
18 January 2006 | San Jose, California, United States
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