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Paradigms for Real-Time Video Communication and for Video Distribution
KTH, School of Electrical Engineering (EES), Sound and Image Processing.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of new information technologies has drastically changed the way that we lead our lives. Communication technologies in particular have had a great impact on our day-to-day behavior. For example, it is now common to hear the voice and see the face of our loved-ones on another continents, or work with colleagues across the globe on a daily basis. With this change in behavior and the fast adoption of emerging technologies, new challenges in the telecommunications area are arising. This thesis is concerned with two such challenges: real-time video communication and video distribution.

The latency constraint in real-time video communication is in essence incompatible with the uncertainty of best-effort networks, such as the Internet. The recent arrival of smart-phones has added another requirement to the application, in terms of the limited computational and battery power. The research community has invested a large amount of effort in developing techniques that allow a mobile sender to outsource video encoding complexity to an unconstrained receiver by means of a feedback channel. We question that approach with respect to real-time applications, arguing that long round-trip-times may render any feedback unusable at best, and costly in practice. We investigate the effect of channel round-trip-times on the popular distributed video coding setup, as well as on the traditional hybrid video coding architecture. Using a simple analytical framework, we propose the use of systems that adapt to the video content and the network in real- time. Our results show that substantial improvements in video quality can be achieved when the feedback channel is used correctly.

The use of mobile devices has also a significant impact on the application of video distribution. In general, the multitude of devices that can be used to download and view video places new requirements on video distribution systems. The system must not only be able to scale to a large number of receivers in a bandwidth efficient manner, it must also support a wide range of network capacities and display capabilities. We address this problem by optimizing the set of rates that is used to provide video to receivers with heterogeneous requirements. Our approach is based on a favorable interpretation of the underlying mathematical problem, allowing the use of well-known quantization theoretic concepts. The resulting solution provides the possibility to design video distribution systems that adapt to changes in receiver characteristics online, with minimal delay.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , xi, 45 p.
Series
Trita-EE, ISSN 1653-5146 ; 2011:031
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-32203ISBN: 978-91-7415-956-1OAI: oai:DiVA.org:kth-32203DiVA: diva2:409608
Public defence
2011-04-26, Salongen, Info-baren, Lavoisier, Osquarsbacke 31, Stockholm, 08:00 (English)
Opponent
Supervisors
Note
QC 20110411Available from: 2011-04-11 Created: 2011-04-08 Last updated: 2011-04-28Bibliographically approved
List of papers
1. Frame-Bufferless Sum-Rate Constrained Video Encoding using Feedback
Open this publication in new window or tab >>Frame-Bufferless Sum-Rate Constrained Video Encoding using Feedback
2010 (English)In: IEEE International Conference on Image Processing, 2010, 797-800 p.Conference paper (Refereed)
Abstract [en]

We investigate the design of a frame-bufferless and low-latency videocommunication system, where the encoder has no access to any previous frames and only one use of feedback communication from the decoder to the encoder is allowed in encoding each frame. This strict requirement on encoder complexity and system latency is of critical importance in designing low complexity realtime video communication systems, where the encoder is limited in storage and computing resources and the use of the feedback channel must not incur accumulated receiver playback delay. We propose a simple online statistical model that captures the time-varying video process and develop a general framework that explores how to best utilize the feedback and distributed source coding mechanisms to minimize the overall communicationrate. Our analysis and experimental results validate the efficiency of the proposed system and highlight its potential in practical system design.

Series
, IEEE International Conference on Image Processing ICIP, ISSN 1522-4880
Keyword
Frame bufferless, distributed video coding, feedback, low complexity, low latency
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-32199 (URN)10.1109/ICIP.2010.5652602 (DOI)000287728000197 ()2-s2.0-78651111600 (ScopusID)978-1-4244-7994-8 (ISBN)
Conference
2010 IEEE INTERNATIONAL CONFERENCE ON IMAGE PROCESSING
Note
QC 20110411Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2011-04-11Bibliographically approved
2. Power-Constrained Low-Latency Video Encoding using Feedback
Open this publication in new window or tab >>Power-Constrained Low-Latency Video Encoding using Feedback
2010 (English)In: IEEE transactions on circuits and systems for video technology (Print), ISSN 1051-8215Article in journal (Other academic) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-32200 (URN)
Note
QS 20120315Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2012-03-20Bibliographically approved
3. A Quantization Theoretic Perspective on Simulcast and Layered Multicast Optimization
Open this publication in new window or tab >>A Quantization Theoretic Perspective on Simulcast and Layered Multicast Optimization
2012 (English)In: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 20, no 2, 585-593 p.Article in journal (Refereed) Published
Abstract [en]

We consider rate optimization in multicast systems that use several multicast trees on a communication network. The network is shared between different applications. For that reason, we model the available bandwidth for multicast as stochastic. For specific network topologies, we show that the multicast rate optimization problem is equivalent to the optimization of scalar quantization. We use results from rate-distortion theory to provide a bound on the achievable performance for the multicast rate optimization problem. A large number of receivers makes the possibility of adaptation to changing network conditions desirable in a practical system. To this end, we derive an analytical solution to the problem that is asymptotically optimal in the number of multicast trees. We derive local optimality conditions, which we use to describe a general class of iterative algorithms that give locally optimal solutions to the problem. Simulation results are provided for the multicast of an i.i.d. Gaussian process, an i.i.d. Laplacian process, and a video source.

Keyword
Communication network, multicast, network topology, optimization, routing
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-32201 (URN)10.1109/TNET.2011.2169085 (DOI)000303068300020 ()2-s2.0-84859943313 (ScopusID)
Funder
ICT - The Next Generation
Note

QC 20120801

Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2013-04-11Bibliographically approved
4. On Bandwidth-Efficient Video Distribution Through Multi-Rate Video Encoding
Open this publication in new window or tab >>On Bandwidth-Efficient Video Distribution Through Multi-Rate Video Encoding
2011 (English)In: IEEE transactions on multimedia, ISSN 1520-9210, E-ISSN 1941-0077Article in journal (Other academic) Submitted
National Category
Computer and Information Science
Identifiers
urn:nbn:se:kth:diva-32202 (URN)
Note
QS 20120316Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2012-03-16Bibliographically approved

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