With the explosive growth of video applications over the Internet, many approaches have been proposed to stream video effectively over packet switched, best-effort networks. In this paper, we propose a receiver-driven protocol for simultaneous video streaming from multiple senders to a single receiver in order to achieve higher throughput, and to increase tolerance to packet loss and delay due to network congestion. Our receiver-driven protocol employs a novel rate allocation algorithm (RAA) and a packet partition algorithm (PPA). The RAA, run at the receiver, determines the sending rate for each sender by taking into account available network bandwidth, channel characteristics, and a prespecified, fixed level of forward error correction, in such a way as to minimize the probability of packet loss. The PPA, run at the senders based on a set of parameters estimated by the receiver, ensures that every packet is sent by one and only one sender, and at the same time, minimizes the startup delay. Using both simulations and Internet experiments, we demonstrate the effectiveness of our protocol in reducing packet loss.

This paper examines the effectiveness of combining multiple description coding (MDC) and multiple path transport (MPT) for video and image transmission in a multihop mobile radio network. The video and image information is encoded nonhierarchically into multiple descriptions with the following objectives. The received picture quality should be acceptable, even if only one description is received and every additional received description contributes to enhanced picture quality. Typical applications will need a higher bandwidth/higher reliability connection than that provided by a single link in current mobile networks. For supporting these applications, a mobile node may need to set up and use multiple paths to the desired destination, either simply because of the lack of raw bandwidth on a single channel or because of its poor error characteristics, which reduce its effective throughput. In the context of this work, the principal reasons for considering such an architecture are providing high bandwidth and more robust end-to-end connections. We describe a protocol architecture that addresses this need and, with the help of simulations, we demonstrate the feasibility of this system and compare the performance of the MDC-MPT scheme to a system using layered coding and asymmetrical paths for the base and enhancement layers.

The use of multiple description (MD) video coding and path diversity has been proposed to provide improved performance over lossy packet networks [1]. The goal of this work was to develop models to accurately and quickly predict and compare the distortion of MD video coding and path diversity against conventional single description (SD) video delivered over a single path. In the process, we developed (1) a model for the loss process of a two-path path diversity system, and (2) a distortion model that maps the loss model to MD distortion values. Given these models we present a number of comparisons between MD video coding and path diversity and conventional SD video over a single path. The proposed model for path diversity may also be useful in other applications not related to MD coding. Furthermore, other forms of MD coding may be analyzed using similar models for MD distortion.

Media streaming over best-effort packet networks such as the Internet is quite challenging because of the dynamic and unpredictable available bandwidth, loss rate, and delay. Recently, streaming over multiple paths to provide path diversity has emerged as an approach to help overcome these problems. This paper provides an overview of the benefits and use of path diversity for media streaming. The different approaches for media coding and streaming over multiple paths are examined, together with architectures for achieving path diversity between single or multiple senders and a single receiver. Important examples include using the distributed servers in a content delivery network to provide path diversity to a requesting client, using multiple 802.11 wireless access points to provide path diversity to a mobile client, and using relays to provide low-latency media communication. The design, analysis, and operation of media streaming systems that use path diversity are considered, with emphasis on the accurate performance models needed to select the best paths or best servers.

In this paper, we present error-resilient Internet video transmission using path diversity and rate-distortion optimized reference picture selection. Under this scheme, the optimal packet dependency is determined adapting to channel characteristics and video content, to achieve a better trade-off between coding efficiency and forming independent streams to increase errorresilience. Packets are sent over the selected path that minimizes the distortion, while taking advantage of path diversity. Experiments demonstrate that the proposed scheme provides significant gains over video redundancy coding and the NACK mode of conventional reference picture selection.

Typical video applications may need a higher bandwidth and/or higher reliability connection than that provided by a single link in current or emerging wireless networks. We propose to employ path diversity to provide higher bandwidth and more robust end-to-end connections than that affordable by a single path. Under this transport environment, two viable strategies for video coding are multiple description coding (MDC) and layered coding (LC). MDC is more effective when the underlying application has a very stringent delay constraint and the round trip time on each path is relatively long. LC can be a good alternative when limited retransmission of the base layer is acceptable and when it is feasible to apply unequal error protection over different paths. This paper describes the general issues involved in integrating MDC/LC with multiple path transport, and compares the performances of MDC and LC, under different path conditions.

We consider the problem of how to enable the streaming of live video content from a single server to a large number of clients. One recently proposed approach relies on the cooperation of the video clients in forming an application layer multicast tree over which the video is propagated. Video continuity is maintained as client departures disrupt the multicast tree, using multiple description coded (MDC) streams multicast over several application layer trees. While this maintains continuity, it can cause video quality fluctuation as clients depart and trees are reconstructed around them. In this paper we develop a scheme using the transmission of a single-description coded video over an application layer multicast tree formed by cooperative clients. Video continuity is maintained in spite of tree disruption caused by departing clients using a combination of two techniques: 1) providing time-shifted streams at the server and allowing clients that suffer service disconnection to join a video channel of the time-shifted stream, and 2) using video patching to allow a client to catch up with the progress of a video program. Simulation experiments demonstrate that our design can achieve uninterrupted service, while not compromising the video quality, at moderate cost.

We investigate how to transmit video with low latency when multiple burst-loss channels are available. We present a transmission strategy based on feedback for multiple description video. The strategy determines dynamically on which channels video frames and probe packets should be sent. Its goal is to find reliable paths and send independent descriptions on different channels. A multiple description with restart coding scheme is used and ensures a high level of error concealment. When errors are detected and a description is corrupted, the scheme selects a reliable ref- erence frame to restart the stream. We also show that the rate of probe packets can be rate-distortion optimized. Experiments demonstrate significant gains over other schemes such as video redundancy coding.

We present Dagster, an end-host multicast scheme for delivering multimedia streams. Unlike previous schemes, Dagster does not constrain the amount of bandwidth a node must donate. Instead, it relies on a novel incentive scheme to encourage nodes to contribute more bandwidth to improve the total capacity of the system. The key idea behind the incentive is that Dagster allows a node with more donated bandwidth to preempt another node in the system. Dagster also allows a host to receive from multiple parents at the same time, thus is more resilient to node failures. Our simulation results show that Dagster’s design leads to low rejection rate, high resilience to failure and smaller diameter. Furthermore, nodes that donate more bandwidth have lower rejection rate and are positioned fewer overlay hops away from the source, providing incentives for nodes to increase their contribution. 1.

In a previous work [1], we proposed an optimal multi-path selection method for multiple description (MD) encoded video streaming. 1 To do so, we first modelled multi-path streaming and then developed an expression, i.e., an objective (cost) function, that estimated average streaming distortion in terms of network statistics, media characteristics and application requirements. Naturally, the ultimate goal was to find the set of paths that minimized this cost function. However, finding such sets of paths turned out to be intractable in large topologies. Hence, in this paper, we provide a fast heuristics-based solution by exploiting the infrastructure features of the Internet. The simulations run over various random Internet topologies show that the proposed heuristic is able to find a good solution in a much shorter time than the brute-force approach. Particularly, this heuristic is best suited to such interactive multimedia applications as video-conferencing and VoIP, where multi-path computation is a time-critical process. In addition, it is also suitable for the clients whose processing power capabilities are limited. 1.