434 research outputs found
Joint Source/FEC Rate Selection for Optimal MPEG-2 Video Delivery
This paper deals with the optimal allocation of MPEG-2 encoding and media-independent FEC rates under a total given bandwidth. The optimality is defined in terms of minimum perceptual end-to-end distortion given a set of video and network parameters. We first derive the set of equations leading to the residual loss process parameters. That is, the packet loss ratio and the average burst length after FEC decoding. We then show that the perceptual source distortion decreases exponentially with the MPEG-2 source rate. We also demonstrate that the perceptual distortion due to data lossis directly proportional to the number of lost macroblocks, and therefore decreases with the amount of channel protection. Finally, we derive the global set of equations that lead to the optimal dynamic rate allocation. The optimal distribution is shown to outperform classical FEC schemes, thanks to its adaptivity to the scene complexity, to the available bandwidth and to the network conditions
Enhancement of Adaptive Forward Error Correction Mechanism for Video Transmission Over Wireless Local Area Network
Video transmission over the wireless network faces many challenges. The most critical challenge is related to packet loss. To overcome the problem of packet loss,
Forward Error Correction is used by adding extra packets known as redundant packet or parity packet. Currently, FEC mechanisms have been adopted together with Automatic Repeat reQuest (ARQ) mechanism to overcome packet losses and avoid network congestion in various wireless network conditions. The number of FEC packets need to be generated effectively because wireless network usually has varying network conditions. In the current Adaptive FEC mechanism, the FEC packets are decided by the average queue length and average packet retransmission times. The Adaptive FEC mechanisms have been proposed to suit the network condition by generating FEC packets adaptively in the wireless network. However, the current Adaptive FEC mechanism has some major drawbacks such as the reduction of recovery performance which injects too many excessive FEC packets into the network. This is not flexible enough to adapt with varying wireless network condition. Therefore, the enhancement of Adaptive FEC mechanism (AFEC) known as Enhanced Adaptive FEC (EnAFEC) has been proposed. The aim is to improve recovery performance on the current Adaptive FEC mechanism by injecting FEC packets dynamically based on varying wireless network conditions. The EnAFEC mechanism is implemented in the simulation environment using Network Simulator 2 (NS-2). Performance evaluations are also carried out. The EnAFEC was tested with the random uniform error model. The results from experiments and performance analyses showed that EnAFEC mechanism outperformed the other Adaptive FEC mechanism in terms of recovery efficiency. Based on the findings, the optimal amount of FEC generated by EnAFEC mechanism can recover high packet loss and produce good video quality
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Multimedia delivery in the future internet
The term “Networked Media” implies that all kinds of media including text, image, 3D graphics, audio
and video are produced, distributed, shared, managed and consumed on-line through various networks,
like the Internet, Fiber, WiFi, WiMAX, GPRS, 3G and so on, in a convergent manner [1]. This white
paper is the contribution of the Media Delivery Platform (MDP) cluster and aims to cover the Networked
challenges of the Networked Media in the transition to the Future of the Internet.
Internet has evolved and changed the way we work and live. End users of the Internet have been confronted
with a bewildering range of media, services and applications and of technological innovations concerning
media formats, wireless networks, terminal types and capabilities. And there is little evidence that the pace
of this innovation is slowing. Today, over one billion of users access the Internet on regular basis, more
than 100 million users have downloaded at least one (multi)media file and over 47 millions of them do so
regularly, searching in more than 160 Exabytes1 of content. In the near future these numbers are expected
to exponentially rise. It is expected that the Internet content will be increased by at least a factor of 6, rising
to more than 990 Exabytes before 2012, fuelled mainly by the users themselves. Moreover, it is envisaged
that in a near- to mid-term future, the Internet will provide the means to share and distribute (new)
multimedia content and services with superior quality and striking flexibility, in a trusted and personalized
way, improving citizens’ quality of life, working conditions, edutainment and safety.
In this evolving environment, new transport protocols, new multimedia encoding schemes, cross-layer inthe
network adaptation, machine-to-machine communication (including RFIDs), rich 3D content as well as
community networks and the use of peer-to-peer (P2P) overlays are expected to generate new models of
interaction and cooperation, and be able to support enhanced perceived quality-of-experience (PQoE) and
innovative applications “on the move”, like virtual collaboration environments, personalised services/
media, virtual sport groups, on-line gaming, edutainment. In this context, the interaction with content
combined with interactive/multimedia search capabilities across distributed repositories, opportunistic P2P
networks and the dynamic adaptation to the characteristics of diverse mobile terminals are expected to
contribute towards such a vision.
Based on work that has taken place in a number of EC co-funded projects, in Framework Program 6 (FP6)
and Framework Program 7 (FP7), a group of experts and technology visionaries have voluntarily
contributed in this white paper aiming to describe the status, the state-of-the art, the challenges and the way
ahead in the area of Content Aware media delivery platforms
Application-Layer FEC Scheme Configuration Optimization via Hybrid Simulated Annealing
An optimization technique based on an adapted combination of simulated
annealing (SA) and tabu search (TS) is presented. This method aims at finding
near-optimal unequal error protection (UEP) application-layer FEC code
configurations. This approach is intended to smartly protect audio and video
transmission over IP networks when hard time restrictions apply. The considered
code is a UEP version of the widely-used Pro-MPEG COP3 codes enabling the use
of several matrices of dissimilar size and thus of unequal recovery capability.
Finding the optimal configuration frequently requires the evaluation of a large
solution space. So, to fulfill the imposed constraints, SA is adapted to the
specifics of the scenario. In particular, the annealing schedule is conditioned
by the real-time restrictions. Furthermore, solution neighborhood structures
are determined by a proposed definition of distance between protection
configurations, which, jointly with TS, conditions the selection of candidate
solutions. Experimental results show a significantly improved performance of
the optimization process, which invariably fulfills imposed timing constraints,
at the expense of a very low distortion increase, when compared to using
exhaustive search. These results allow the use of UEP Pro-MPEG COP3 codes for
protecting video and audio transmission, which distinctly outperforms the
standard code in a wide range of scenarios
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