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Dissertations / Theses on the topic 'Video telephony'
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1
Chung, Jin Yee. "Wireless video telephony." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409602.
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2
Högberg, Robert. "Video telephony in an IP-based set-top box environment." Thesis, Linköping University, Department of Computer and Information Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2351.
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This thesis evaluates and shows an implementation of a video telephony solution for network connected set-top boxes based on the SIP protocol for managing sessions.
Unlike other video telephony implementations the set-top box does not handle both audio and video, but only video. A separate phone is used to handle audio. To maintain compatibility with other video telephony implementations, which expect a single SIP device with both audio and video capabilities, a mechanism to merge the audio (SIP-phone) and video (set-top box) into a single entity was developed using a back-to-back user agent.
Due to the set-top boxes'limited hardware it could be impossible to have video compression and decompression performed by the set-top boxes. However, numerous performance tests of compression algorithms showed that the computational power available in the set-top boxes is sufficient to have acceptable frame rate and image quality in a video telephony session. A faster CPU or dedicated hardware for video compression and decompression would however be required in order to compete with dedicated video telephony systems available today.
The implemented video telephony system is based on open standards such as SIP, RTP and H.261, which means interoperability with other video telephony implementations, such as Microsoft's Windows Messenger 4.7, is good.
3
Ma, Zhenyu. "Semi-synchronous video for Deaf Telephony with an adapted synchronous codec." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_2950_1370593938.
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Communication tools such as text-based instant messaging, voice and video relay services, real-time video chat and mobile SMS and MMS have successfully been used among Deaf people. Several years of field research with a local Deaf community revealed that disadvantaged South African Deaf
people preferred to communicate with both Deaf and hearing peers in South African Sign Language as opposed to text. Synchronous video chat and video
relay services provided such opportunities. Both types of services are commonly available in developed regions, but not in developing countries like South
Africa. This thesis reports on a workaround approach to design and develop an asynchronous video communication tool that adapted synchronous video
codecs to store-and-forward video delivery. This novel asynchronous video tool provided high quality South African Sign Language video chat at the
expense of some additional latency. Synchronous video codec adaptation consisted of comparing codecs, and choosing one to optimise in order to
minimise latency and preserve video quality. Traditional quality of service metrics only addressed real-time video quality and related services. There was no
uch standard for asynchronous video communication. Therefore, we also enhanced traditional objective video quality metrics with subjective
assessment metrics conducted with the local Deaf community.
4
Dawood, Muneeb. "Error resilient packet switched H.264 video telephony over third generation networks." Thesis, De Montfort University, 2010. http://hdl.handle.net/2086/4849.
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Real-time video communication over wireless networks is a challenging problem because wireless channels suffer from fading, additive noise and interference, which translate into packet loss and delay. Since modern video encoders deliver video packets with decoding dependencies, packet loss and delay can significantly degrade the video quality at the receiver. Many error resilience mechanisms have been proposed to combat packet loss in wireless networks, but only a few were specifically designed for packet switched video telephony over Third Generation (3G) networks. The first part of the thesis presents an error resilience technique for packet switched video telephony that combines application layer Forward Error Correction (FEC) with rateless codes, Reference Picture Selection (RPS) and cross layer optimization. Rateless codes have lower encoding and decoding computational complexity compared to traditional error correcting codes. One can use them on complexity constrained hand-held devices. Also, their redundancy does not need to be fixed in advance and any number of encoded symbols can be generated on the fly. Reference picture selection is used to limit the effect of spatio-temporal error propagation. Limiting the effect of spatio-temporal error propagation results in better video quality. Cross layer optimization is used to minimize the data loss at the application layer when data is lost at the data link layer. Experimental results on a High Speed Packet Access (HSPA) network simulator for H.264 compressed standard video sequences show that the proposed technique achieves significant Peak Signal to Noise Ratio (PSNR) and Percentage Degraded Video Duration (PDVD) improvements over a state of the art error resilience technique known as Interactive Error Control (IEC), which is a combination of Error Tracking and feedback based Reference Picture Selection. The improvement is obtained at a cost of higher end-to-end delay. The proposed technique is improved by making the FEC (Rateless code) redundancy channel adaptive. Automatic Repeat Request (ARQ) is used to adjust the redundancy of the Rateless codes according to the channel conditions. Experimental results show that the channel adaptive scheme achieves significant PSNR and PDVD improvements over the static scheme for a simulated Long Term Evolution (LTE) network. In the third part of the thesis, the performance of the previous two schemes is improved by making the transmitter predict when rateless decoding will fail. In this case, reference picture selection is invoked early and transmission of encoded symbols for that source block is aborted. Simulations for an LTE network show that this results in video quality improvement and bandwidth savings. In the last part of the thesis, the performance of the adaptive technique is improved by exploiting the history of the wireless channel. In a Rayleigh fading wireless channel, the RLC-PDU losses are correlated under certain conditions. This correlation is exploited to adjust the redundancy of the Rateless code and results in higher Rateless code decoding success rate and higher video quality. Simulations for an LTE network show that the improvement was significant when the packet loss rate in the two wireless links was 10%. To facilitate the implementation of the proposed error resilience techniques in practical scenarios, RTP/UDP/IP level packetization schemes are also proposed for each error resilience technique. Compared to existing work, the proposed error resilience techniques provide better video quality. Also, more emphasis is given to implementation issues in 3G networks.
5
Newman, John M. "The effects of synchronous voice and video tools on acceptance of online communications by students in undergraduate technology courses /." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3276959.
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Thesis (Ph. D.)--University of Nevada, Reno, 2007."May, 2007." Includes bibliographical references (leaves 85-104). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2007]. 1 microfilm reel ; 35 mm.
6
Hallberg, Andreas. "A protocol for decentralized video conferencing with WebRTC : Solving the scalability problems of conferencing services for the web." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202963.
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Video conferencing has been a part of many communication platforms over the years. Over the last decades users have moved from dedicated telephony networks to the Internet, and recently to the Web. With the introduction of Web Real-Time Communication (WebRTC) it is now possible to make voice- and video calls simply by visiting a web page, without having to install any additional software. Services that enable multi-user conferences are quite common. However existing solutions such as the Multipoint Control Unit (MCU) inherently do not scale and can be a single point of failure, due to its centralized architecture. This can lead to high maintenance costs and poor service availability.To solve the scalability- and availability problems of video-conferencing services, a decentralized alternative to the MCU is proposed. A decentralized conferencing system uses the distributed resources of its users instead of relying on a central server. This means that the system can handle an increasing number of users without having to upgrade any server infrastructure. Additionally, failures are only partial and can happen regularly without affecting the rest of the system. This report presents the development of a protocol built on top of WebRTC that enables completely decentralized multi-user conferencing. It includes a distributed algorithm for voice-activated switching to reduce the computation and network resources used. A load-balancing technique based on media stream relays is used to distribute the resource requirements of the conference participants. The protocol is implemented as a Javascript library that can be included in a web application. A proof-of-concept web application is developed using the library and its performance is evaluated. The performance data is analyzed and the results are used to make incremental improvements to the protocol and implementation. Although not all features of the protocol are implemented, the tests show promising results. The application allows multiple users to participate in high-definition video conferences, with no server infrastructure aside from a Mini PC that hosts a web server and a WebRTC signaling server.Videokonferenser har varit en del av många olika kommunikationsplattformar genom åren. Tekniken har yttats från dedikerade telefonnnät,, till Internet, och på senare tid till webben. I och med introduktionen av WebRTC (Web Real-Time Communication) är deti dag möjligt att enkelt deltaga i röst- och videosamtal genom att gå till en webbsida utan att behöva installera någon programvara annat an en webbläsare. De flesta existerande konferenstjänster är byggda med en centraliserad arkitektur, vilket kan leda till tekniska problem när antalet användare ökar eller när fel uppstår i systemens centrala servrar. Dessa problem kan leda till driftstopp och skada tjänstens tillgänglighet för användarna. Den här rapporten täcker utvecklingen av ett protokoll som tillsammans med WebRTC kan användas för att bygga en helt decentraliserad konferenstjänst. Målet är att tjänsten ska vara oberoende av centrala servrar, och på så vis lösa problemen med skalbarhet och tillgänglighet. Protokollet implementeras i en webbapplikation som testas och utvärderasöver flera iterationer för att hitta nya förbättringar. Testerna visar lovande resultat. Slutsatsen dras det är fullt möjligt att bygga en konferenstjänst på detta sätt, och möjligheter för framtida optimeringar och testfall föreslås.
7
Gandham, Venkata Kishore. "Virtual visual system for interactive video applications over telephone networks." FIU Digital Commons, 1995. http://digitalcommons.fiu.edu/etd/3449.
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8
Yoshida, Minoru. "Barriers for telecommunication accessibility and needs assessment of video relay services (VRS) : utilization of VRS for the deaf community /." Online version of thesis, 2008. http://hdl.handle.net/1850/6923.
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9
Karlsson, Johan. "Development and Standardization of a "Failure". : Ericsson and the Video Telephone in the 1970's." Thesis, Uppsala University, Department of Economic History, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122924.
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10
Stegmann, Johann. "Design and implementation of a digital video recorder, with live video streaming to cellphone over mobile broadband." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2642.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007.The work presented in this Thesis relates to the increased capabilities of the mobile Internet and the possible use of cellphones as an enhancement to video surveillance systems. The focus of the Thesis is on the delivery of live video content to Java enabled cellphones. The various characteristics, capabilities and limitations of the mobile networks- and phones are investigated. Various options for streaming video content to cellphones are also explored. The design and implementation of a digital surveillance system with the ability to stream live video to a cellphone is presented. Two versions of the streaming protocol are developed and implemented in cellphone applications, with which the video stream can be viewed. An evaluation and real-life testing of the applications are presented. Recommendations regarding further enhancements are provided.
11
Bugdayci, Done. "Stereo Video Broadcasting Over Dvb-h." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614024/index.pdf.
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This thesis proposes a complete framework of an end-to-end transmission of stereo video
to mobile devices using DVB-H. Block diagram of the system is presented and operations
conducted on the video at each layer are explained. Parameters and methodologies that may
make a robust transmission possible are discussed. The transmission performance is analyzed
in terms of error robustness under various coding methods, prediction structures, layering
and protection strategies for different contents and channel conditions. It also investigates
the effect of rate allocation between video quality and protection over robust transmission
in erroneous environment. This works provides directive conclusions on the selection of the
mentioned parameters and methods.
12
Zheng, Min. "Side information exploitation, quality control and low complexity implementation for distributed video coding." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/46760/.
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Distributed video coding (DVC) is a new video coding methodology that shifts the highly complex motion search components from the encoder to the decoder, such a video coder would have a great advantage in encoding speed and it is still able to achieve similar rate-distortion performance as the conventional coding solutions. Applications include wireless video sensor networks, mobile video cameras and wireless video surveillance, etc. Although many progresses have been made in DVC over the past ten years, there is still a gap in RD performance between conventional video coding solutions and DVC. The latest development of DVC is still far from standardization and practical use. The key problems remain in the areas such as accurate and efficient side information generation and refinement, quality control between Wyner-Ziv frames and key frames, correlation noise modelling and decoder complexity, etc. Under this context, this thesis proposes solutions to improve the state-of-the-art side information refinement schemes, enable consistent quality control over decoded frames during coding process and implement highly efficient DVC codec. This thesis investigates the impact of reference frames on side information generation and reveals that reference frames have the potential to be better side information than the extensively used interpolated frames. Based on this investigation, we also propose a motion range prediction (MRP) method to exploit reference frames and precisely guide the statistical motion learning process. Extensive simulation results show that choosing reference frames as SI performs competitively, and sometimes even better than interpolated frames. Furthermore, the proposed MRP method is shown to significantly reduce the decoding complexity without degrading any RD performance. To minimize the block artifacts and achieve consistent improvement in both subjective and objective quality of side information, we propose a novel side information synthesis framework working on pixel granularity. We synthesize the SI at pixel level to minimize the block artifacts and adaptively change the correlation noise model according to the new SI. Furthermore, we have fully implemented a state-of-the-art DVC decoder with the proposed framework using serial and parallel processing technologies to identify bottlenecks and areas to further reduce the decoding complexity, which is another major challenge for future practical DVC system deployments. The performance is evaluated based on the latest transform domain DVC codec and compared with different standard codecs. Extensive experimental results show substantial and consistent rate-distortion gains over standard video codecs and significant speedup over serial implementation. In order to bring the state-of-the-art DVC one step closer to practical use, we address the problem of distortion variation introduced by typical rate control algorithms, especially in a variable bit rate environment. Simulation results show that the proposed quality control algorithm is capable to meet user defined target distortion and maintain a rather small variation for sequence with slow motion and performs similar to fixed quantization for fast motion sequence at the cost of some RD performance. Finally, we propose the first implementation of a distributed video encoder on a Texas Instruments TMS320DM6437 digital signal processor. The WZ encoder is efficiently implemented, using rate adaptive low-density-parity-check accumulative (LDPCA) codes, exploiting the hardware features and optimization techniques to improve the overall performance. Implementation results show that the WZ encoder is able to encode at 134M instruction cycles per QCIF frame on a TMS320DM6437 DSP running at 700MHz. This results in encoder speed 29 times faster than non-optimized encoder implementation. We also implemented a highly efficient DVC decoder using both serial and parallel technology based on a PC-HPC (high performance cluster) architecture, where the encoder is running in a general purpose PC and the decoder is running in a multicore HPC. The experimental results show that the parallelized decoder can achieve about 10 times speedup under various bit-rates and GOP sizes compared to the serial implementation and significant RD gains with regards to the state-of-the-art DISCOVER codec.
13
Aksay, Anil. "Error Resilient Multiview Video Coding And Streaming." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611682/index.pdf.
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In this thesis, a number of novel techniques for error resilient coding and streaming for multiview video are presented. First of all, a novel coding technique for stereoscopic video is proposed where additional coding gain is achieved by downsampling one of the views spatially or temporally based on the well-known theory that the human visual system can perceive high frequencies in 3D from the higher quality view. Stereoscopic videos can be coded at a rate upto 1.2 times that of monoscopic videos with little visual quality degradation with the proposed coding technique. Next, a systematic method for design and optimization of multi-threaded multi-view video encoding/decoding algorithms using multi-core processors is proposed. The proposed multi-core decoding architectures are compliant with the current international standards, and enable multi-threaded processing with negligible loss of encoding efficiency and minimum processing overhead. End-to-end 3D Streaming system over Internet using current standards is implemented. A heuristic methodology for modeling the end-toend rate-distortion characteristic of this system is suggested and the parameters of the system is optimally selected using this model. End-to-end 3D Broadcasting system over DVB-H using current standards is also implemented. Extensive testing is employed to show the importance and characteristics of several error resilient tools. Finally we modeled end-to-end RD characteristics to optimize the encoding and protection parameters.
14
Gurses, Eren. "Optimal Streaming Of Rate Adaptable Video." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607352/index.pdf.
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In this study, we study the dynamics of network adaptive video streaming and propose novel algorithms for rate distortion control in video streaming. While doing so, we maintain inter-protocol fairness with TCP (Transmission Control Protocol) that is the dominant transport protocol in the current Internet. The proposed algorithms are retransmission-based and necessitate the use of playback buffers in order to tolerate the extra latency introduced by retransmissions. In the first part, we propose a practical network-adaptive streaming scheme based on TCP transport and the idea of Selective Frame Discarding (SFD) that makes use of two-layer temporally scalable video. The efficacy of the SFD scheme is validated for playout buffer times in the order of seconds and therefore makes it suitable more for delay tolerant streaming applications.
In the second part of the thesis, we propose an application layer rate-distortion control algorithm which provides Optimal Scheduling and Rate Control (OSRC) policies in the average reward sense in order to achieve efficient streaming of video. The Optimal Scheduling (OS) we propose maximizes the probability of successfully on time delivery according to a prespecified set of rate constraints, and different channel conditions by using Markov Decision Process (MDP) models. On the other hand optimal rate control (RC) is achieved by calculating the optimal rate constraint which minimizes the average distortion of a video streaming session by making use of the video distortion model derived for lossy channels and achievable success probabilities provided by the set of optimal schedules. For numerical examples, we focus on an equation-based TCP friendly rate control (TFRC) protocol where transport layer retransmissions are disabled and Fine Granular Scalable (FGS) coded video is used for improved rate adaptation capabilities but with an additional rate distortion penalty. The efficacy of the proposed OSRC algorithm is demonstrated by means of both analytical results and ns-2 simulations.
15
Dinc, Mustafa Baris. "Design And Fabrication Of A Detector Logarithmic Video Amplifier." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613617/index.pdf.
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In this thesis a single stage detector logarithmic video amplifier is designed with a dynamic range of 40dB in 2-6GHz frequency band. Since the detector logarithmic video amplifier (DLVA) is used to convert the power of the RF signals to video voltages in logarithmic scale, it can be regarded as a logarithmic converter instead of logarithmic amplifier. The design is composed of two main parts: The Schottky diode detector rectifies the incoming RF signal and produces a video voltage and the logarithmic amplifier transforms the scale of the video voltage from linear scale to logarithmic scale in order to observe the RF signals with a wide amplitude range. The approximation of the logarithmic function is obtained by the summation of the output currents of the differential amplifiers operating as logarithmic stages. Offset voltage of the DLVA is minimized in order to obtain maximum sensitivitythis makes the detection of RF signals with low power possible. The study is composed of mainly three parts: First, brief information about logarithmic amplification techniques is given and the circuit architecture is developed for logarithmic amplification and video detection, second these circuits are simulated and finally the design is implemented and tested.
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Atar, Neriman. "Video Segmentation Based On Audio Feature Extraction." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610397/index.pdf.
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In this study, an automatic video segmentation and classification system based on audio features has been presented. Video sequences are classified such as videos with &ldquospeech&rdquo
, &ldquo
music&rdquo
, &ldquo
crowd&rdquo
and &ldquo
silence&rdquo
. The segments that do not belong to these regions are left as &ldquo
unclassified&rdquo
. For the silence segment detection, a simple threshold comparison method has been done on the short time energy feature of the embedded audio sequence. For the &ldquo
speech&rdquo
, &ldquo
music&rdquo
and &ldquo
crowd&rdquo
segment detection a multiclass classification scheme has been applied. For this purpose, three audio feature set have been formed, one of them is purely MPEG-7 audio features, other is the audio features that is used in [31] the last one is the combination of these two feature sets. For choosing the best feature a histogram comparison method has been used. Audio segmentation system was trained and tested with these feature sets. The evaluation results show that the Feature Set 3 that is the combination of other two feature sets gives better performance for the audio classification system. The output of the classification system is an XML file which contains MPEG-7 audio segment descriptors for the video sequence. An application scenario is given by combining the audio segmentation results with visual analysis results for getting audio-visual video segments.
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Ayran, Orhan. "Reliable Real-time Video Communication In Wireless Sensor Networks." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608233/index.pdf.
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Many wireless sensor network (WSN) applications require efficient multimedia communication capabilities. However, the existing communication protocols in the literature mainly aim to achieve energy efficiency and reliability objectives and do not address the multimedia communication challenges in WSN. In this thesis, comprehensive performance evaluation of the existing transport protocols is performed and it has been shown that the existing proposals achieve very poor performance in terms of large set of metrics such as packet delivery rate, end-to-end packet delay, bandwidth and energy efficiency, frame peak signal-to-noise ratio (PSNR), delay-bounded frame PSNR, frame delivery probability, frame end-to-end delay and jitter. Based on these results, an energy-efficient real-time and reliable video sensor communication protocol (VSCP) is introduced for WSN. VSCP estimates video quality perceived by sink using lost segments of video frames and aims to maintain the overall reliability at a given level with minimum energy expenditure. Source data rates are adjusted in a quality adaptable manner according to the network conditions and the overall reliability computed by sink. QSC (quality scalable coding) encoding technique is used to produce a nearly constant quality video at a given maximum data rate during adjustment of source data rates. Performance evaluations show that VSCP protocol significantly outperforms the existing proposals in terms of multimedia communication performance metrics in WSN.
18
Ozkalayci, Burak Oguz. "Multi-view Video Coding Via Dense Depth Field." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607517/index.pdf.
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Emerging 3-D applications and 3-D display technologies raise
some transmission problems of the next-generation multimedia data.
Multi-view Video Coding (MVC) is one of the challenging topics in
this area, that is on its road for standardization via ISO MPEG. In
this thesis, a 3-D geometry-based MVC approach is proposed and
analyzed in terms of its compression performance. For this purpose,
the overall study is partitioned into three preceding parts. The
first step is dense depth estimation of a view from a fully
calibrated multi-view set. The calibration information and
smoothness assumptions are utilized for determining dense
correspondences via a Markov Random Field (MRF) model, which is
solved by Belief Propagation (BP) method. In the second part, the
estimated dense depth maps are utilized for generating (predicting)
arbitrary (other camera) views of a scene, that is known as novel
view generation. A 3-D warping algorithm, which is followed by an
occlusion-compatible hole-filling process, is implemented for this
aim. In order to suppress the occlusion artifacts, an intermediate
novel view generation method, which fuses two novel views generated
from different source views, is developed. Finally, for the last
part, dense depth estimation and intermediate novel view generation
tools are utilized in the proposed H.264-based MVC scheme for the
removal of the spatial redundancies between different views. The
performance of the proposed approach is compared against the
simulcast coding and a recent MVC proposal, which is expected to be
the standard recommendation for MPEG in the near future. These
results show that the geometric approaches in MVC can still be
utilized, especially in certain 3-D applications, in addition to
conventional temporal motion compensation techniques, although the
rate-distortion performances of geometry-free approaches are quite
superior.
19
Onur, Ozgur Deniz. "A Complexity-utility Framework For Optimizing Quality Ofexperience For Visual Content In Mobile Devices." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614088/index.pdf.
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Subjective video quality and video decoding complexity are jointly optimized in order to determine the video encoding parameters that will result in the best Quality of Experience (QoE) for an end user watching a video clip on a mobile device. Subjective video quality is estimated by an objective criteria, video quality metric (VQM), and a method for predicting the video quality of a test sequence from the available training sequences with similar content characteristics is presented. Standardized spatial index and temporal index metrics are utilized in order to measure content similarity. A statistical approach for modeling decoding complexity on a hardware platform using content features extracted from video clips is presented. The overall decoding complexity is modeled as the sum of component complexities that are associated with the computation intensive code blocks present in state-of-the-art hybrid video decoders. The content features and decoding complexities are modeled as random parameters and their joint probability density function is predicted as Gaussian Mixture Models (GMM). These GMMs are obtained off-line using a large training set comprised of video clips. Subsequently, decoding complexity of a new video clip is estimated by using the available GMM and the content features extracted in real time. A novel method to determine the video decoding capacity of mobile terminals by using a set of subjective decodability experiments that are performed once for each device is also proposed. Finally, the estimated video quality of a content and the decoding capacity of a device are combined in a utility-complexity framework that optimizes complexity-quality trade-off to determine video coding parameters that result in highest video quality without exceeding the hardware capabilities of a client device. The simulation results indicate that this approach is capable of predicting the user viewing satisfaction on a mobile device.
20
Brunson, Jeremy Linn. "The practice and organization of sign language interpreting in video relay service : an institutional ethnography of access." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available, full text:, 2008. http://wwwlib.umi.com/cr/syr/main.
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21
Heberling, Rachel Elaine. "Obsolete Communication: An Apparition of the Disembodied Hand and Voice." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306854239.
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22
Belin, Sofia, and Josefina Brinkenius. "Upplevelse av bedömningssamtal hos gravida inför internetbaserad kognitiv beteendeterapi : Har valmöjlighet och besöksmodalitet betydelse?" Thesis, Linnéuniversitetet, Institutionen för psykologi (PSY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-103688.
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Depression förekommer under 10% av alla graviditeter och medför risker för både den gravida och barnet. Syfte: Studien IKBT för gravida med depression syftar till att bekräfta tidigare studiers resultat av IKBT-behandling samt utvärdera olika besöksmodaliteter, telefonsamtal, videosamtal eller fysiskt besök, för bedömningssamtalet. Metod: 26 gravida (graviditetsvecka 8–30 vid antagning) med samtidig egentlig depression randomiserades till antingen eget val av besöksmodalitet eller randomiserades till en viss besöksmodalitet för sitt bedömningssamtal. Efteråt tillfrågades deltagarna om sina upplevelser av bedömningssamtalet avseende innehåll, modalitet samt hur Covid-19 pandemin påverkade deras inställning. Resultat: Det förelåg ingen statistisk signifikant skillnad mellan hur de tre besöksmodalitetsgrupperna eller mellan de som fick välja gentemot de som blev tilldelade en besöksmodalitet upplevde bedömningssamtalet. Kvalitativa data pekar mot att deltagarna hade föredragit fysiskt besök men uppskattade andra möjligheter med anledning av Covid-19 pandemin. Slutsats: Deltagarna var generellt lika nöjda med sitt bedömningssamtal oavsett besöksmodalitet och om de själva hade fått välja besöksmodalitet eller ej. Att erbjuda olika besöksmodaliteter ökar tillgängligheten och möjliggör behandling med IKBT för gravida med depression från hela landet. För att validera resultatet krävs vidare forskning med större antal deltagare.Depression is present during 10% of all pregnancies and leads to risk for both the pregnant and the baby. Objective: The study ICBT towards pregnant with depression aims to confirm earlier studies results of ICBT-treatment and to evaluate different visiting modalities, telephone call, video call or face to face meeting, of the assessment interview. Method: 26 pregnant women (gestational week 8–30 at intake) currently suffering from major depressive disorder randomized to either free choice of visiting modality or randomized to a certain visiting modality of the assessment interview. Afterwards the participants were asked about their experience of the assessment interview regarding content, modality and how the Covid-19 pandemic affected their attitude. Results: There was no statistically significant difference between how the three visiting modality groups or between the ones who got to choose opposite the ones who was assigned a visiting modality regarding the experience of the assessment interview. Qualitative data indicates that the participants would have preferred a face to face meeting but appreciated other possibilities due to the Covid-19 pandemic. Conclusion: The participants was in general equally satisfied with their assessment interview regardless visiting modality or if they got to choose their visiting modality or not. To offer different visiting modalities increases the availability and enables treatment with ICBT towards pregnant with depression throughout the country. These results need to be replicated in larger trials to validate.
23
Koz, Alper. "Watermarking For 3d Representations." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608886/index.pdf.
Full textAbstract:
In this thesis, a number of novel watermarking techniques for different 3D representations are presented. A novel watermarking method is proposed for the mono-view video, which might be interpreted as the basic implicit representation of 3D scenes. The proposed method solves the common flickering problem in the existing video watermarking schemes by means of adjusting the watermark strength with respect to temporal contrast thresholds of human visual system (HVS), which define the maximum invisible distortions in the temporal direction. The experimental results indicate that the proposed method gives better results in both objective and subjective measures, compared to some recognized methods in the literature.
The watermarking techniques for the geometry and image based representations of 3D scenes, denoted as 3D watermarking, are examined and classified into three groups, as 3D-3D, 3D-2D and 2D-2D watermarking, in which the pair of symbols identifies whether the watermark is embedded-detected in a 3D model or a 2D projection of it. A detailed literature survey on 3D-3D watermarking is presented that mainly focuses on protection of the intellectual property rights of the 3D geometrical representations. This analysis points out the specific problems in 3D-3D geometry watermarking , such as the lack of a unique 3D scene representation, standardization for the coding schemes and benchmarking tools on 3D geometry watermarking.
For 2D-2D watermarking category, the copyright problem for the emerging free-view televisions (FTV) is introduced. The proposed watermarking method for this original problem embeds watermarks into each view of the multi-view video by utilizing the spatial sensitivity of HVS. The hidden signal in a selected virtual view is detected by computing the normalized correlation between the selected view and a generated pattern, namely rendered watermark, which is obtained by applying the same rendering operations which has occurred on the selected view to the original watermark. An algorithm for the estimation of the virtual camera position and rotation is also developed based on the projective planar relations between image planes. The simulation results show the applicability of the method to the FTV systems.
Finally, the thesis also presents a novel 3D-2D watermarking method, in which a watermark is embedded into 3-D representation of the object and detected from a 2-D projection (image) of the same model. A novel solution based on projective invariants is proposed which modifies the cross ratio of the five coplanar points on the 3D model according to the watermark bit and extracts the embedded bit from the 2D projections of the model by computing the cross-ratio. After presenting the applicability of the algorithm via simulations, the future directions for this novel problem for 3D watermarking are addressed.
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Sävenstedt, Stefan. "Telecare of frail elderly : reflections and experiences among health personnel and family members /." Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-339.
Full text
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Huebner, Uwe. "Workshop: INFRASTRUKTUR DER ¨DIGITALEN UNIVERSIAET¨." Universitätsbibliothek Chemnitz, 2000. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200000692.
Full textAbstract:
Gemeinsamer Workshop von Universitaetsrechenzentrum und
Professur Rechnernetze und verteilte Systeme (Fakultaet fuer
Informatik) der TU Chemnitz.
Workshop-Thema: Infrastruktur der ¨Digitalen Universitaet¨
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Jaume, Bennasar Andrés. "Las nuevas tecnologías en la administración de justicia. La validez y eficacia del documento electrónico en sede procesal." Doctoral thesis, Universitat de les Illes Balears, 2009. http://hdl.handle.net/10803/9415.
Full textAbstract:
La tesis se encarga de analizar, por un lado, la integración y el desarrollo de las nuevas tecnologías en la Administración de Justicia; y, por otro, los parámetros que constituyen la validez y eficacia del documento electrónico. La primera cuestión se centra en la configuración de los Sistemas de Información de la Oficina Judicial y del Ministerio Fiscal, así como de la informatización de los Registros Civiles, donde el art. 230 LOPJ es la pieza clave. Se estudian sus programas, aplicaciones, la videoconferencia, los ficheros judiciales y las redes de telecomunicaciones que poseen la cobertura de la firma electrónica reconocida, donde cobran gran relevancia los convenios de colaboración tecnológica. La digitalización de las vistas quizá sea una de las cuestiones con más trascendencia, teniendo en cuenta que el juicio es el acto que culmina el proceso. Aunque no todos los proyectos adoptados en el ámbito de la e.justicia se han desarrollado de forma integral, ni han llegado a la totalidad de los órganos judiciales. El objetivo final es lograr una Justicia más ágil y de calidad, a lo cual aspira el Plan Estratégico de Modernización de la Justicia 2009-2012 aprobado recientemente.
En referencia a la segunda perspectiva, no cabe duda que el Ordenamiento jurídico y los tribunales, en el ámbito de la justicia material, otorgan plena validez y eficacia al documento electrónico. Nuestra línea de investigación se justifica porque cada vez son más los procesos que incorporan soportes electrónicos de todo tipo, ya sea al plantearse la acción o posteriormente como medio de prueba (art. 299.2 LEC). Entre otros temas examinamos el documento informático, la problemática que rodea al fax, los sistemas de videograbación y el contrato electrónico.
La tesi s'encarrega d'analitzar, per una part, la integració i el desenvolupament de les noves tecnologies dins l´Administració de Justícia; i, per l'altra, els paràmetres que constitueixen la validesa i l'eficàcia del document electrònic.
La primera qüestió es centra en la configuració dels Sistemes d´Informació de l´Oficina Judicial i del Ministeri Fiscal, així com de la informatització dels Registres Civils, on l'art. 230 LOPJ es la peça clau. S'estudien els seus programes, aplicacions, la videoconferència, el fitxers judicials i les xarxes de telecomunicacions que tenen la cobertura de la firma electrònica reconeguda, on cobren gran rellevància els convenis de col·laboració tecnològica. La digitalització de les vistes tal vegada sigui una de les qüestions amb més transcendència, tenint amb compte que el judici es l'acte que culmina el procés. Però no tots el projectes adoptats en l'àmbit de la e.justicia s'han desenvolupat d'una manera integral ni han arribat a la totalitat dels òrgans judicials. L'objectiu final es assolir una Justícia més àgil i de qualitat, al que aspira el Pla Estratègic de Modernització de la Justícia 2009-2012 aprovat recentment.
En referència a la segona perspectiva, no hi ha dubte que l´Ordenament jurídic i els tribunals, en l'àmbit de la justícia material, donen plena validesa i eficàcia al document electrònic. La nostra línia d'investigació es justifica perquè cada vegada son més el processos que incorporen suports electrònics de tot tipus, ja sigui quant es planteja l'acció o posteriorment como a medi de prova (art. 299.2 LEC). Entre altres temes examinem el document informàtic, la problemàtica que envolta al fax, els sistemes de videogravació i el contracte electrònic.
The thesis seeks to analyse, on the one hand, the integration and development of the new technologies in the Administration of Justice; and, on the other, the parameters which constitute the validity and efficiency of the electronic document.
The first question centres on the configuration of the Information Systems of the Judicial Office and the Public Prosecutor, as well as the computerisation of the Civil Registers, where the art. 230 LOPJ it's the part key. Their programmes, applications, the Video Conferencing, the judicial registers and the telecommunication networks which are covered by the recognised electronic signatures, are studied, where the agreements on technological collaboration gain great relevance. The digitalisation of evidence might perhaps be one of the questions with most consequence, bearing in mind that the judgment is the act by which the process is culminated. Although not all the projects adopted within the compass of e.justice have developed completely nor have reached all the judicial organs. The final objective is to achieve an agile, quality Justice, to which the recently approved Strategic Plan for the Modernisation of Justice aspires.
With reference to the second perspective, there is no doubt that the juridical Ordinance and the tribunals within the compass of material justice grant full validity and efficacy to the electronic document. Our line of investigation is justified because there are more and more processes which are sustained by electronic supports of all kinds, whether it be at the establishment of the action or later, as a proof of it (art. 299.2 LEC). Amongst other things, we examine the computerised document, the problems which surround the fax, the systems for video recording and the electronic contract.
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Wang, Jeng-Jie, and 王證傑. "Active Switching System for "Video Telephony Service" Based on H.323." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/84295072403601240408.
Full textAbstract:
碩士國立交通大學
電信工程系
88
The study focuses on the solution of “Video Telephony Service” over Internet to solve the limitation of Telephony Service with VoIP technology based on H.323 standard under current environment, and considers the complex of system affiliated with Video Communication application. Presently, academic community had done lots of researches in H.323 protocol regarding QoS Control, Rate control, and Error control; however, it seldom concentrated on the current network environment, the structure limitation, user habit and system integration. Now it proposes a new structure based on H.323 and should review precisely the information exchange procedure including control message and multi-media data. It also redesigns a switching system for “Video Telephony Service” which is an application oriented switching system and could be constructed at every service node. This is just like the concept of “Active Switching”. It analyses each document of protocols under H.323 Protocol Stack and a serial of technique papers which is published in Vol.15, No. 6, Aug. 1997, IEEE JSAV journal and studies related topics of Rate Control, CODEC Design, Synchronization Control, and Admission Control. It also investigates and integrates current networking environment (Ex. Ethernet, TCP/IP), PBX Interface, CTI Planning, Hub/Switch Design, Video Capture Card Application, and Windows Programming.
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Alipour, Hanieh. "QoS Enabled Video Telephony with a Virtualized HSS in a 4G EPC Environment." Thesis, 2013. http://spectrum.library.concordia.ca/978015/1/Alipour_MSc_S2014.pdf.
Full textAbstract:
Video Telephony is the real time exchange of voice and video between end-users. It is the basis of a wide range of applications (e.g. Multiparty games, distance learning). Quality of service (QoS) enables network performance control for meeting specific applications and/or end-user requirements. It is a differentiating factor for service providers. Evolved Packet Core (EPC) is the new core network for 3GPP 4G networks. Home Subscriber Server (HSS) is the standardized master database of 3GPP next generation networks including video telephony networks and EPC. It contains the subscription related information that is needed to support the network entities when they handle sessions. The constant increase in the number of subscribers is one of the challenges for future mobile networks including video telephony networks and EPC. Virtualization is a technique used to emulate the physical characteristics of resources. It enables efficiency in resource usage and is a key technology for scalability and elasticity.
This thesis proposes an architecture for QoS Enabled video telephony with a Virtualized HSS (VHSS) in a 3GPP 4G environment. It makes two main contributions. Firstly, it proposes a differentiated QoS service delivery platform that relies on EPC. This platform enables the provisioning of a refined differentiated QoS scheme which allows prioritization between different sessions of a same video telephony application running on a same network. This new scheme is a differentiating factor for service providers. Second it proposes a preliminary mechanism for a scalable and elastic HSS in order to cope with the increasing number of subscribers. This is done by decomposing the HSS into three main layers (diameter layer, database computation layer and storage layer). Each of these layers are virtualized and can grow/shrink independently. We have built a proof of concept prototype to demonstrate the feasibility of the proposed architecture. Performance measurements have also been made to evaluate viability.
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Ko, I.-Ling, and 柯伊玲. "Market Segmentation Analysis of Video Telephony Service: A Study on the consumers of Hsin-Chu City." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/28489124945640072652.
Full textAbstract:
碩士國立交通大學
科技管理研究所
85
This thesis reports on a segmentation of. video telephony service This segmentation was obtained by assimilating from three major theories in marketing, namely, consumer behavior theory, market segmentation theory, and lifestyle theory. A questionnaire was used to investigating the consumer behavior of people who live in Shin-Chu city . Statistical methods were used to analyze data obtained from survey questionnaire. The following were the results.1.Eight lifestyle factors were identified.f Image Scanner grow fast. Besides, 2.Three segments were classified by using eight lifestyle factors.end to be a 3.There was significant difference among four segments in “ usage occasion”unde“Behavioral variable”.4.There was significant difference among four segments in“Sex”、“Age”、 “Occupation”and“Income”under“Demographic variable”.5.There was significant difference among three segments in Characteristics of“video telephony service ”.Marketing strategies were recommended to service providers by above results.l
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"Marketing a new service by a public utility company: the case study on Videolink." Chinese University of Hong Kong, 1991. http://library.cuhk.edu.hk/record=b5886831.
Full textAbstract:
by Luk Wai-keung.Thesis (M.B.A.)--Chinese University of Hong Kong, 1991.
Bibliography: leaf 80.
ABSTRACT --- p.i
TABLE OF CONTENTS --- p.iii
Chapter
Chapter I. --- INTRODUCTION --- p.1
Proliferation of New Products --- p.1
Impact of Market Forces --- p.2
The Case of New Service Launch --- p.4
Outline of Study --- p.5
Chapter II. --- METHODOLOGY --- p.6
Multi-dimensional Approach --- p.6
Literature Survey --- p.7
Review of Company's Own Records --- p.8
Discussion with Product Management Team --- p.9
Field Observation of Marketing Activities --- p.9
User Interviews --- p.10
Chapter III. --- INDUSTRY & COMPANY OVERVIEW --- p.12
Global Trend in the Telecom Industry --- p.12
Rapid Development & Proliferation of New Services --- p.12
Deregulation of Telecommunication Industry --- p.13
Telecommunication Industry in Hong Kong --- p.14
The Hong Kong Telephone Company - Monopoly & Its Impacts --- p.17
Company Strengths --- p.19
Company Weaknesses --- p.20
Chapter IV. --- VIDEOLINK SERVICE & ITS DEVELOPMENT IN HONG KONG --- p.22
What is VideoLink ？ --- p.22
Some Technical Information --- p.23
VideoLink Service Development in Hong Kong --- p.24
Development History --- p.24
Service Format & Pricing --- p.26
Preliminary Assessment of Marketing Progress --- p.27
Chapter V. --- VIDEOLINK MARKETING PROFILES --- p.29
Product Profile --- p.29
Product Strengths --- p.29
Product Weaknesses --- p.32
Competitive Profile --- p.33
Competing Products & Services --- p.33
Evaluation of Competitors --- p.34
Customer Profile --- p.37
User Requirements & Characteristics --- p.37
Application Types & Market Potentials --- p.39
Chapter VI. --- ANALYSING THE MARKETING PROBLEMS --- p.44
Review of Marketing Program --- p.44
Product Strategy --- p.45
Pricing Strategy --- p.45
Sales & Distribution --- p.46
Promotion Strategy --- p.47
Identifying the Marketing Problems --- p.49
Exploring the Underlying Causes --- p.52
Technology Driven Culture --- p.52
Monopoly Status --- p.54
Organisational Hindrance --- p.55
Chapter VII. --- STRATEGIC RECOMMENDATION --- p.57
Reformulating the Marketing Program --- p.57
Identifying the Target Market --- p.57
The Product Offerings --- p.60
The Promotion Mix --- p.62
The Sales Strategy --- p.63
Establishing a Marketing Orientation --- p.64
Chapter VIII. --- CONCLUSION --- p.70
APPENDIX
Chapter 1 --- User Interviews Discussion Guideline --- p.73
Chapter 2 --- VideoLink Tariff Schedule --- p.75
Chapter 3 --- Customer Profile Analysis --- p.76
Chapter 4 --- Orangization Structure of VideoLink Team --- p.77
Chapter 5 --- VideoLink Service Configuration - Comparison of Fixed & Switched Connections --- p.78
Chapter 6 --- Hong Kong Telephone Corporate Vision Program --- p.79
BIBLIOGRAPHY --- p.80
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Chen, Chang-Hong, and 陳長宏. "Video Telephone and H.263 Coding Techniques." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/30484678664586938087.
Full textAbstract:
碩士國立臺灣大學
電機工程學系
85
In this thesis, a region-based blurring algorithm to reduce the bitrate in very low bitrate video coding is proposed. The algorithm reduces the bitrate by passing the original background image through a filter before motion estimation. In the algorithm, each original images will be segmented into foreground and background at first. After segmentation, the background, which is of less importance for human vision, will be blurred through a blurring filter, while the foreground is kept unchanged. The bitrate for head-and-shoulder type sequence can achieve 5%~20% bitrate saving by the blurring algorithm according to the complexity of the sequence. Consider the human vision model, PSNR degradation in the background is not evident. If we use the blurring algorithm but allocate it with the same bitrate as the original sequence, about 0.5~1dB gain in foreground can be achieved due to bits reallocation. In segmentation part of the algorithm, a region-growing-based segmentation efficient for the special purpose of blurring is explored. The requirement of segmentation for blurring has to be fast enough, but doesn't have to provide find accuracy. This is fulfilled with the region-growing-based segmentation. To further reduce the computation time, a fast search algorithm, such as 3-step search, is applied to the segmented background. Since the background has already been blurred, the local minimums are smoothed out and thus the fast search algorithm will not degrade too much quality any more. Beside the algorithm above, a real videophone system prototype based on the algorithm is constructed for test. The videophone system is built on PC platform, and can achieve 3 more frames per second.
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Chien, Chih-Peng, and 簡志鵬. "Reducing Temperature Rise of Video Telephones." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24821434941832252816.
Full textAbstract:
碩士元智大學
機械工程學系
98
With diverse functions and long time use of video phone, central processing unit operates too fast to radiate high temperature. These reasons cause chips are damaged and high temperature on the surface as well. Therefore, the experiments focused on the original reasons of high temperature and to lower temperature further. The topics are as below: (1) To add the area of radiations; (2) To increase convection; (3) To choose metallic materials with good thermal conductivity; (4) To conduct high temperature to low; (5) To lower the temperature of charge areas to improve the operation. In this paper, the tests and modifications of testing and manufacturing products are as below, to design more holes in the bottom and back, to rise the feet 3mm of bottom, to move 3V and 5V of charge areas, to join the top shielding together with heat sink and to join the base shielding together with power area, to lower down the circuit of DECT Board form 10V to 8V in order to lower power charge, to paste aluminum foil to isolate temperature, and to add radiated slice to conduct temperature. Finally, these tests and modifications shall lower the temperature 17˚C of video phone’s surface. Indeed, it shall help related industries to improve their technologies and find out the problems of video phone when people dedicate in this industry.
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Middleton-Green, Laura, A. Gadoud, Beverley Norris, Anita R. Sargeant, S. Nair, L. Wilson, H. Livingstone, and Neil A. Small. "“A Friend in the Corner”: Supporting people at home in the last year of life via telephone and video consultation – an evaluation." 2016. http://hdl.handle.net/10454/10075.
Full textAbstract:
YesObjective: To evaluate a 24/7, nurse led telephone and video-consultation support service for patients thought to be in the last year of life in Bradford, Airedale, Wharfedale and Craven. Method: Activity and other data recorded at the time of calls were analysed. Interviews with 13 participants captured patients and carers perspectives. Results: Between April 1st 2014 and March 31st 2015, 4648 patients were registered on the Gold Line. 42% had a non-cancer diagnosis and 46% were not known to specialist palliative care services. The median time on the caseload was 49 days (range 1-504 days). 4533 telephone calls and 573 video consultations were received from 1813 individuals. 39% of the 5106 calls were resolved by Gold Line team without referral to other services. 69% of calls were made outside normal working hours. Interviews with patients and carers reported experiences of support and reassurance and the importance of practical advice. Conclusion: A nurse led, 24/7 telephone and video consultation service can provide valuable support for patients identified to be in the last year of life and their cares. The line enabled them to feel supported and remain in their place of residence, reducing avoidable hospital admissions and use of other services. Providing this service may encourage health care professionals to identify patients approaching the last year of life, widening support offered to this group of patients beyond those known to specialist palliative care services.
Health Foundation adn Shared Purpose
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"Workshop: INFRASTRUKTUR DER ¨DIGITALEN UNIVERSIAET¨." Technische Universität Chemnitz, 2000. https://monarch.qucosa.de/id/qucosa%3A17644.
Full textAbstract:
Gemeinsamer Workshop von Universitaetsrechenzentrum und
Professur Rechnernetze und verteilte Systeme (Fakultaet fuer
Informatik) der TU Chemnitz.
Workshop-Thema: Infrastruktur der ¨Digitalen Universitaet¨