432 research outputs found
Transmission of 3D Scenes over Lossy Channels
This paper introduces a novel error correction scheme for the transmission of three-dimensional scenes over unreliable networks. We propose a novel Unequal Error Protection scheme for the transmission of depth and texture information that distributes a prefixed amount of redundancy among the various elements of the scene description in order to maximize the quality of the rendered views. This target is achieved exploiting also a new model for the estimation of the impact on the rendered views of the various geometry and texture packets which takes into account their relevance in the coded bitstream and the viewpoint required by the user. Experimental results show how the proposed scheme effectively enhances the quality of the rendered images in a typical depth-image-based rendering scenario as packets are progressively decoded/recovered by the receiver
Error resilient stereoscopic video streaming using model-based fountain codes
Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Science of Bilkent University, 2009.Thesis (Ph.D.) -- Bilkent University, 2009.Includes bibliographical references leaves 101-110.Error resilient digital video streaming has been a challenging problem since
the introduction and deployment of early packet switched networks. One of
the most recent advances in video coding is observed on multi-view video coding
which suggests methods for the compression of correlated multiple image
sequences. The existing multi-view compression techniques increase the loss sensitivity
and necessitate the use of efficient loss recovery schemes. Forward Error
Correction (FEC) is an efficient, powerful and practical tool for the recovery of
lost data. A novel class of FEC codes is Fountain codes which are suitable to be
used with recent video codecs, such as H.264/AVC, and LT and Raptor codes are
practical examples of this class. Although there are many studies on monoscopic
video, transmission of multi-view video through lossy channels with FEC have
not been explored yet. Aiming at this deficiency, an H.264-based multi-view
video codec and a model-based Fountain code are combined to generate an effi-
cient error resilient stereoscopic streaming system. Three layers of stereoscopic
video with unequal importance are defined in order to exploit the benefits of Unequal
Error Protection (UEP) with FEC. Simply, these layers correspond to intra frames of left view, predicted frames of left view and predicted frames of right
view. The Rate-Distortion (RD) characteristics of these dependent layers are de-
fined by extending the RD characteristics of monoscopic video. The parameters
of the models are obtained with curve fitting using the RD samples of the video,
and satisfactory results are achieved where the average difference between the
analytical models and RD samples is between 1.00% and 9.19%. An heuristic
analytical model of the performance of Raptor codes is used to obtain the residual
number of lost packets for given channel bit rate, loss rate, and protection
rate. This residual number is multiplied with the estimated average distortion
of the loss of a single Network Abstraction Layer (NAL) unit to obtain the total
transmission distortion. All these models are combined to minimize the end-toend
distortion and obtain optimal encoder bit rates and UEP rates. When the
proposed system is used, the simulation results demonstrate up to 2dB increase
in quality compared to equal error protection and only left view error protection.
Furthermore, Fountain codes are analyzed in the finite length region, and
iterative performance models are derived without any assumptions or asymptotical
approximations. The performance model of the belief-propagation (BP)
decoder approximates either the behavior of a single simulation results or their
average depending on the parameters of the LT code. The performance model of
the maximum likelihood decoder approximates the average of simulation results
more accurately compared to the model of the BP decoder. Raptor codes are
modeled heuristically based on the exponential decay observed on the simulation
results, and the model parameters are obtained by line of best fit. The analytical
models of systematic and non-systematic Raptor codes accurately approximate
the experimental average performance.Tan, A SerdarPh.D
Enabling Quality-Driven Scalable Video Transmission over Multi-User NOMA System
Recently, non-orthogonal multiple access (NOMA) has been proposed to achieve
higher spectral efficiency over conventional orthogonal multiple access.
Although it has the potential to meet increasing demands of video services, it
is still challenging to provide high performance video streaming. In this
research, we investigate, for the first time, a multi-user NOMA system design
for video transmission. Various NOMA systems have been proposed for data
transmission in terms of throughput or reliability. However, the perceived
quality, or the quality-of-experience of users, is more critical for video
transmission. Based on this observation, we design a quality-driven scalable
video transmission framework with cross-layer support for multi-user NOMA. To
enable low complexity multi-user NOMA operations, a novel user grouping
strategy is proposed. The key features in the proposed framework include the
integration of the quality model for encoded video with the physical layer
model for NOMA transmission, and the formulation of multi-user NOMA-based video
transmission as a quality-driven power allocation problem. As the problem is
non-concave, a global optimal algorithm based on the hidden monotonic property
and a suboptimal algorithm with polynomial time complexity are developed.
Simulation results show that the proposed multi-user NOMA system outperforms
existing schemes in various video delivery scenarios.Comment: 9 pages, 6 figures. This paper has already been accepted by IEEE
INFOCOM 201
Efficient mobile video transmission based on a joint coding scheme
In this paper, we propose a joint coding design which uses the Symbol Forward Error Correction (S-FEC) at the application layer. The purpose of this work is on one hand to minimize the Packet Loss Rate (PLR) and, on the other hand to maximize the visual quality of video transmitted over a wireless network (WN).The scheme proposed is founded on a FEC adaptable with the semantics of the H.264/AVC video encoding.This mechanism relies upon a rate distortion algorithm, controlling the channel code rates under the global rate constraints given by the WN.Based on a data partitioning (DP) tool, both packet type and packet length are taken into account by the proposed optimization mechanism which leads to unequal error protection (UEP). The performance of the proposed JSCC unequal error control is illustrated over wireless network by performing simulations under different channel conditions. The simulation results are then compared with an equal error protection (EEP) scheme
Cross-Layer Framework for Multiuser Real Time H.264/AVC Video Encoding and Transmission over Block Fading MIMO Channels Using Outage Probability
We present a framework for cross-layer optimized real time multiuser encoding of video using a single layer H.264/AVC and transmission over MIMO wireless channels. In the proposed cross-layer adaptation, the channel of every user is characterized by the probability density function of its channel mutual information and the performance of the H.264/AVC encoder is modeled by a rate distortion model that takes into account the channel errors. These models are used during the resource allocation of the available slots in a TDMA MIMO communication system with capacity achieving channel codes. This framework allows for adaptation to the statistics of the wireless channel and to the available resources in the system and utilization of the multiuser diversity of the transmitted video sequences. We show the effectiveness of the proposed framework for video transmission over Rayleigh MIMO block fading channels, when channel distribution information is available at the transmitter
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