We propose a framework for popularity-driven rate allocation in H.264/MVC-based multi-view video communications
when the overall rate and the rate necessary for decoding each view are constrained in the delivery
architecture. We formulate a rate allocation optimization problem that takes into account the popularity of
each view among the client population and the rate-distortion characteristics of the multi-view sequence so that
the performance of the system is maximized in terms of popularity-weighted average quality. We consider the
cases where the global bit budget or the decoding rate of each view is constrained. We devise a simple ratevideo-
quality model that accounts for the characteristics of interview prediction schemes typical of multi-view
video. The video quality model is used for solving the rate allocation problem with the help of an interior
point optimization method. We then show through experiments that the proposed rate allocation scheme clearly
outperforms baseline solutions in terms of popularity-weighted video quality. In particular, we demonstrate that
the joint knowledge of the rate-distortion characteristics of the video content, its coding dependencies, and the
popularity factor of each view is key in achieving good coding performance in multi-view video systems.
We consider rate-distortion (RD) optimized multi-flow video delivery in unstructured overlay networks. We show
that this problem can be studied as a distributed rate allocation. To solve the problem over the participating peers
in the overlay, we apply classical decomposition techniques such that the network-wide utility of video distortion is
minimized. Media packets are assumed to be piggy-backed with RD preambles that contain information regarding
their impact on decoder video distortion and their size. This allows for converting the calculated optimal rate
allocation at every node into simple forwarding or dropping actions. Furthermore, the proposed distributed
media streaming framework employs a network inference algorithm for minimizing the flow of duplicate packets
over the network and utilizing thus more efficiently the available resources. Our simulation results indicate that
significant quality benefits can be achieved when the precise RD characteristics of a media presentation are taken
We consider streaming video content over an overlay network of peer nodes. We propose a novel streaming
strategy that is built on utility-based packet scheduling and proportional resource sharing in order to flight against
free-riders. Each of the peers employs a mesh-pull mechanism to organize the download of media packets from
its neighbours. For eficient resource utilization, data units are requested from neighbours based on their utility.
The packet utility is driven by both its importance for the video reconstruction quality at the receiving peer
and its popularity within the peer neighbourhood. In order to discourage free-riding in the system, requesting
peers then share the upload bandwidth of a sending peer in proportion to their transmission rate to that peer .
Our simulation results show that the proposed protocols increase the performance of a mesh-pull P2P streaming
system. Significant improvements are registered relative to existing solutions in terms of average quality and
average decoding rate.
We consider the scenario of video streaming in peer-to-peer networks. A single media server delivers the video
content to a large number of peer hosts by taking advantage of their forwarding capabilities. We propose a
scheme that enables the peers to efficiently distribute the media stream among them. Each of the peers connects
to the streaming server via multiple multicast trees that provide for robustness in the event of peer disconnection.
Moreover, adaptive forwarding of the media content at each peer is enabled by labeling the packets with their
importance for the reconstruction of the media stream. We study the performance of the proposed scheme as
a function of system parameters such as the play-out delay of the media application, the peer population size
and the number of multicast trees employed by the scheme. We show that by placing priorities on forwarding
the individual packets at each peer an improved performance is achieved over conventional peer-to-peer systems
where no such prioritization is deployed. The gains in performance are particularly significant for low-delay
applications and large peer populations.
A system for sender-driven video streaming from multiple servers to a single receiver is considered in this paper. The receiver monitors incoming packets on each network path and returns, to the senders, estimates of the available bandwidth on all the network paths. The senders in turn employ this information to compute transmission schedules for packets belonging to the video stream sent to the receiver. An optimization framework is proposed that enables the senders to compute their transmission schedules in a distributed way,
and yet to dynamically coordinate them over time such that the resulting video quality at the receiver is maximized. Experimental results demonstrate that the proposed streaming framework provides superior performance over distortion-agnostic transmission schemes that perform proportional packet scheduling based only on the available network bandwidths.
Communication over a network bottleneck link is a commonplace in the Internet today. The loss and delay
experienced by packets travelling along the network path between the sender and the receiver are mainly
governed by the characteristics of the bottleneck link, such as available data rate and queue size. In this
work, we propose a framework for rate-distortion optimized packet scheduling with adaptive rate control for
media streaming over network bottleneck links. The framework computes optimal packet schedules, while
adaptively controlling its data rate as a response to the effect that its transmitted packets will have on the
delay experienced on the link. This results into a closed-loop control system which dynamically adjusts its
packet schedules according to its transmission rate. Experimental results demonstrate that our framework
maintains significantly smaller packet delay and smoother transmission rate when streaming over a bottleneck
link relative to rate-distortion optimized packet scheduling without rate control with only a minor loss in
We consider an unconventional procedure for communicating to the
server the receipt of media packets for Internet video streaming.
Instead of separately acknowledging each media packet as it
arrives, we periodically send to the server a single acknowledgment packet, denoted <i>rich acknowledgment</i>, that contains information about all media packets that have arrived at the client by the time the rich acknowledgment is sent. We investigate rate-distortion optimized sender-driven streaming that employs rich acknowledgments. Performance gains of up to 1.3 dB for streaming packetized video content are observed over rate-distortion optimized sender-driven systems that employ conventional acknowledgments.
Studies suggest that the composition of atherosclerotic plaque in the carotid arteries is predictive of stroke risk. The goal of this investigation has been to explore how well the true integrated backscatter (IBS) from plaque regions can be measured <i>non-invasively</i> using ultrasound, based on which plaque composition may be inferred. To obtain the true arterial IBS non-invasively, the scattering and aberrating effect of the intervening tissue layers must be overcome. This is achieved by using the IBS from arterial blood as a reference backscatter, specifically the backscatter from a blood volume along the same scan line as and adjacent to the region of interest. The arterial blood IBS is obtained as an estimated mean of a stochastic process, after clutter removal. We have shown that the variance of the IBS estimate of the blood backscatter signal can be quantified and reduced to a tolerable level. The results are in the form of IBS profiles along the vessel. IBS profiles <i>not normalized with the IBS of the blood-mimicking fluid</i> have been measured for vessels phantom, with and without an intervening inhomogeneous medium; these results are contrasted with the corresponding <i>normalized</i> IBS profiles.