Research and developments of Dirac video codec

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.In digital video compression, apart from storage, successful transmission of the compressed video data over the bandwidth limited erroneous channels is another important issue. To enable a video codec for broadcasting application, it is required to implement the corresponding coding tools (e.g. error-resilient coding, rate control etc.). They are normally non-normative parts of a video codec and hence their specifications are not defined in the standard. In Dirac as well, the original codec is optimized for storage purpose only and so, several non-normative part of the encoding tools are still required in order to be able to use in other types of application. Being the "Research and Developments of the Dirac Video Codec" as the research title, phase I of the project is mainly focused on the error-resilient transmission over a noisy channel. The error-resilient coding method used here is a simple and low complex coding scheme which provides the error-resilient transmission of the compressed video bitstream of Dirac video encoder over the packet erasure wired network. The scheme combines source and channel coding approach where error-resilient source coding is achieved by data partitioning in the wavelet transformed domain and channel coding is achieved through the application of either Rate-Compatible Punctured Convolutional (RCPC) Code or Turbo Code (TC) using un-equal error protection between header plus MV and data. The scheme is designed mainly for the packet-erasure channel, i.e. targeted for the Internet broadcasting application. But, for a bandwidth limited channel, it is still required to limit the amount of bits generated from the encoder depending on the available bandwidth in addition to the error-resilient coding. So, in the 2nd phase of the project, a rate control algorithm is presented. The algorithm is based upon the Quality Factor (QF) optimization method where QF of the encoded video is adaptively changing in order to achieve average bitrate which is constant over each Group of Picture (GOP). A relation between the bitrate, R and the QF, which is called Rate-QF (R-QF) model is derived in order to estimate the optimum QF of the current encoding frame for a given target bitrate, R. In some applications like video conferencing, real-time encoding and decoding with minimum delay is crucial, but, the ability to do real-time encoding/decoding is largely determined by the complexity of the encoder/decoder. As we all know that motion estimation process inside the encoder is the most time consuming stage. So, reducing the complexity of the motion estimation stage will certainly give one step closer to the real-time application. So, as a partial contribution toward realtime application, in the final phase of the research, a fast Motion Estimation (ME) strategy is designed and implemented. It is the combination of modified adaptive search plus semi-hierarchical way of motion estimation. The same strategy was implemented in both Dirac and H.264 in order to investigate its performance on different codecs. Together with this fast ME strategy, a method which is called partial cost function calculation in order to further reduce down the computational load of the cost function calculation was presented. The calculation is based upon the pre-defined set of patterns which were chosen in such a way that they have as much maximum coverage as possible over the whole block. In summary, this research work has contributed to the error-resilient transmission of compressed bitstreams of Dirac video encoder over a bandwidth limited error prone channel. In addition to this, the final phase of the research has partially contributed toward the real-time application of the Dirac video codec by implementing a fast motion estimation strategy together with partial cost function calculation idea.BBC R&D and Brunel University

Developing a regenerative design framework for the built environment : a case study in Chiang Mai, Thailand

Regenerative design offers a sustainable design approach that aims to go beyond mainstream paradigms by prioritising the role of nature as a crucial part of the built environment design. However, previous studies show that current regenerative design frameworks have several factors that impact the efficiency and credibility of their use. Therefore, this study proposes a Regenerative Design Framework for the Thai context (RDF-T), aiming to develop a new framework that can address the gaps in previous studies. Regenerative design is relatively unknown among Thai design practitioners, and this approach has not yet been applied to Thai built environment design projects. RDF-T's structure combines the principle of regenerative design with the ‘Backcasting technique’ and ‘Thai's Rating of Energy and Environmental Sustainability (TREES)’ to strengthen its credibility and capability. This research investigates the potential of RDF-T as a contextual built environment design tool through its application in a 3-day workshop on the development of design guidelines for proposals within an area called Nong Bua in Chiang Mai, Thailand. Qualitative methodology is the main approach of this study, while a quantitative methodology is adopted to support the comprehensive outcomes. Findings reveal that RDF-T can produce a contextual built environment design for the case study area and has the potential to be applied to other built environment projects in Thailand. However, the findings also show that Thai Socio-Ecological Characteristics are important additional factors that can help underpin the efficiency of this framework for future users. In addition, an outcome of this study, the RDF-T manual, offers primary material for regenerative design in the Thai context and supports the application of the framework in different regions across the world.Regenerative design offers a sustainable design approach that aims to go beyond mainstream paradigms by prioritising the role of nature as a crucial part of the built environment design. However, previous studies show that current regenerative design frameworks have several factors that impact the efficiency and credibility of their use. Therefore, this study proposes a Regenerative Design Framework for the Thai context (RDF-T), aiming to develop a new framework that can address the gaps in previous studies. Regenerative design is relatively unknown among Thai design practitioners, and this approach has not yet been applied to Thai built environment design projects. RDF-T's structure combines the principle of regenerative design with the ‘Backcasting technique’ and ‘Thai's Rating of Energy and Environmental Sustainability (TREES)’ to strengthen its credibility and capability. This research investigates the potential of RDF-T as a contextual built environment design tool through its application in a 3-day workshop on the development of design guidelines for proposals within an area called Nong Bua in Chiang Mai, Thailand. Qualitative methodology is the main approach of this study, while a quantitative methodology is adopted to support the comprehensive outcomes. Findings reveal that RDF-T can produce a contextual built environment design for the case study area and has the potential to be applied to other built environment projects in Thailand. However, the findings also show that Thai Socio-Ecological Characteristics are important additional factors that can help underpin the efficiency of this framework for future users. In addition, an outcome of this study, the RDF-T manual, offers primary material for regenerative design in the Thai context and supports the application of the framework in different regions across the world

A slotted-CDMA based wireless-ATM link layer : guaranteeing QoS over a wireless link.

Thesis (M.Sc.)-University of Natal, Durban, 2000.Future wireless networks will have to handle varying combinations of multimedia traffic that present the network with numerous quality of service (QoS) requirements. The continuously growing demand for mobile phones has resulted in radio spectrum becoming a precious resource that cannot be wasted. The current second-generation mobile networks are designed for voice communication and, even with the enhancements being implemented to accommodate data, they cannot efficiently handle the multimedia traffic demands that will be introduced in the near future. This thesis begins with a survey of existing wireless ATM (WATM) protocols, followed by an examination of some medium access control (MAC) protocols, supporting multimedia traffic, and based on code division multiple access (CDMA) physical layers. A WATM link layer protocol based on a CDMA physical layer, and incorporating techniques from some of the surveyed protocols, is then proposed. The MAC protocol supports a wide range of service requirements by utilising a flexible scheduling algorithm that takes advantage of the graceful degradation of CDMA with increasing user interference to schedule cells for transmission according to their maximum bit error rate (BER) requirements. The data link control (DLC) accommodates the various traffic types by allowing virtual channels (VCs) to make use of forward error correction (FEc) or retransmission techniques. The proposed link layer protocol has been implemented on a Blue Wave Systems DSP board that forms part of Alcatel Altech Telecoms' software radio platform. The details and practicality of the implementation are presented. A simulation model for the protocol has been developed using MIL3 's Opnet Modeler. Hence, both simulated and measured performance results are presented before the thesis concludes with suggestions for improvements and future work

Fast Motion Estimation Algorithms for Block-Based Video Coding Encoders

The objective of my research is reducing the complexity of video coding standards in real-time scalable and multi-view applications

Analyzing Voice And Video Call Service Performance Over A Local Area Network

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2010Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2010Bu çalışmada, VOIP teknolojisinden ve bu teknolojiyi kablolu ve kablosuz ortamda gerçeklemenin en önemli darboğazları anlatılacaktır. Ayrıca H.323, SIP (Session Initiation Protocol), Megaco ve MGCP gibi yaygın olarak kullanılan ses iletim protokolleri ve H.261, H.263 ve H.264 gibi görüntü iletim protokollerinden bahsedilmiştir. Ses kodek seçimi ve VOIP servis kalitesine etki eden faktörleri anlatılmaktadır. Bu tezde, ses, görüntü ve veri iletişimini aynı anda bünyesinde barındıran gerçek şebekeler simüle edilecektir. Kullanıcılara rastlantısal olarak ses, görüntü ve FTP gibi birtakım uygulamalar atanmıştır. Ayrıca önerilen kablolu şebekeye, kablosuz bir şebeke ilave edilerek sonuçlar incelenecektir. Optimal servis kalitesini sağlamak için seçilen uygun kuyruklama mekanizmaları ve kodek seçimlerini içeren senaryolar incelenecek ve OPNET ile elde edilmiş simülasyon sonuçları tartışılacaktır.In this study, we present a detailed description of the VoIP and also the most common challenges of implementing voice communication into wireline or wireless networks are discussed. Common voice protocols, such as H.323, Session Initiation Protocol (SIP), Megaco, MGCP and video protocols such as H.261, H.263, H.264 are described as well. CODEC selection and factors affecting VoIP Quality of Service are analyzed. We simulate a real network which includes both voice, video and data communication simultaneously. Workstations are randomly assigned to different applications, such as voice, video and FTP. We will also implement a wireless network to our proposed system. The scenarios including selecting appropriate queuing scheme and codec selection are presented and the simulation results with OPNET are drawn.Yüksek LisansM.Sc

Antennas for small mobile terminals

Digital Video Broadcasting for Handheld Terminals (DVB-H) is a service based on DVB-T (for terrestrial broadcasting). Some differences and changes must be considered to adapt the existing DVB-T technology to the experimental DVB-H one. The purpose of this master thesis is to design the best possible antenna for DVB-H. In order to achieve this, some scenarios are considered such as the influence of the human hand and wood or metal planes (emulating tables). As this antenna must be inside a handheld device, its size will be a very limiting factor. This is worsen by the fact that the wavelength is bigger than the size of the handheld device and so this constraint will add more problems related with small bandwidth, impedance matching, received power, etc. Thanks to the simulations, two planar monopole antennas have been chosen and explained in detail under the different scenarios. It will be seen that these two antennas are small enough to fit in a handheld device and that they can overcome all the problems related with the wavelength, received power, human body interference, etc

Architecture and Remote Interaction Techniques for Digital Media Exchange across 3G Mobile Devices

For users away from the office or home, there is an increasing demand for mobile solutions that offer effective collaborative facilities on the move. The mobile cellular device, or “smart phone”, can offer a ubiquitous platform to deliver such services, provided that its many physical and technological constraints can be overcome. In an effort to better support mobile collaboration, this thesis presents a contributing Mobile Exchange Architecture (MEA) designed to improve upon the capabilities provided by mobile devices to enable synchronous exchange of digital media during a phone conversation using wireless networks and cellular devices. This research includes the design and development of one such MEA in the form of a fully functional Photo-conferencing service, supporting shared remote interaction techniques, simultaneous voice communication and seamless digital media exchange between remote and collocated mobile users. Furthermore, through systematic design, experimental evaluations and field studies we evaluate the effects of different shared remote interaction techniques – 'pointing', 'scaling', 'mixed' and 'hybrid' – assessing the task effort required by users when interacting around shared images across resource constrained mobile devices. This thesis presents a direction for the future development of technologies and methods to enable a new era of scalable always-to-hand mobile collaborative environments.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

NASA Tech Briefs, May 1991

Topics: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

The Winonan

https://openriver.winona.edu/thewinonan1990s/1224/thumbnail.jp