• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 571
  • 101
  • 53
  • 52
  • 43
  • 34
  • 29
  • 24
  • 19
  • 17
  • 16
  • 10
  • 10
  • 9
  • 6
  • Tagged with
  • 1100
  • 314
  • 278
  • 206
  • 142
  • 136
  • 122
  • 121
  • 118
  • 112
  • 94
  • 92
  • 86
  • 83
  • 82
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Videoproduktion och distribution av gudstjänster

Ericsson, Ronnie January 2007 (has links)
Sammanfattning: Det är minst lika många människor som besöker arrangemang och gudstjänster i kyrkor som besöker idrottsevenemang. Det behövs studiogudstjänster dock sänds det allt färre Tv-gudstjänster direkt från kyrkor och medlen för att göra detta är också på väg att minskas. Många som ser dessa gudstjänster har av olika orsaker inte möjlighet att besöka en kyrka. Detta kan t ex bero på funktionshinder och sjukdom men också att många äldre har svårt att förflytta sig och se gudstjänster live. Ett sätt för kyrkorna att nå ut på bredare front skulle kunna vara att använda sig av Internet som media. Syftet med uppsatsen är att genom intervjuer, användningstestning och slutligen prototyptestning, ta fram en lösning för digital överföring av ljud och bild från ett ställe till ett annat via ett IP-nätverk och finna en avvägning mellan det tekniska och användbarheten då användaren har begränsad teknisk kunskap. Vid datainsamlingen användes en kvalitativ forskningsprocess med intervjuer och observation som insamlingstekniker. Vid användningstesterna användes observation som metod och testpersonerna uppmanades att tänka högt. Analysen av testerna visade vikten av att minimera inblandning av för mycket teknik i lösningarna då områdeskunskapen hos användare varierar kraftigt.
252

Investigation of IMS in an IPTV context.

Gustafsson, Tobias January 2006 (has links)
The trends in todays tele- and datacommunication market point toward using IP for all sorts of service delivery ranging from voice calls to TV. The next natural step in this evolution is to provide the same set of services to the end users independent of the access technology and device used. The IP Multimedia Subsystem (IMS) is an IP based telecommunications platform which targets this and lets the operators develop new services once which can then be used on many different devices. This thesis examines the integration of IPTV and IMS. Can IMS be used to deliver TV services and can the IPTV set-top-boxes of today be used as clients in IMS? Since this is a new and previously unexamined area an explorative approach is taken. The aim is to identify how such an integration could be performed and the possible problems which have to be solved. To assist in this exploration a TV-push service based on IMS technology is constructed. Based on the experiences from this service a general architecture for IPTV in IMS is suggested. A number of problems crucial to solve for a successful integration are identified and possible solutions to these are discussed.
253

Quality-Driven Cross-Layer Protocols for Video Streaming over Vehicular Ad-Hoc Networks

Asefi, Mahdi 30 August 2011 (has links)
The emerging vehicular ad-hoc networks (VANETs) offer a variety of applications and new potential markets related to safety, convenience and entertainment, however, they suffer from a number of challenges not shared so deeply by other types of existing networks, particularly, in terms of mobility of nodes, and end-to-end quality of service (QoS) provision. Although several existing works in the literature have attempted to provide efficient protocols at different layers targeted mostly for safety applications, there remain many barriers to be overcome in order to constrain the widespread use of such networks for non-safety applications, specifically, for video streaming: 1) impact of high speed mobility of nodes on end-to-end QoS provision; 2) cross-layer protocol design while keeping low computational complexity; 3) considering customer-oriented QoS metrics in the design of protocols; and 4) maintaining seamless single-hop and multi-hop connection between the destination vehicle and the road side unit (RSU) while network is moving. This thesis addresses each of the above limitations in design of cross-layer protocols for video streaming application. 1) An adaptive MAC retransmission limit selection scheme is proposed to improve the performance of IEEE 802.11p standard MAC protocol for video streaming applications over VANETs. A multi-objective optimization framework, which jointly minimizes the probability of playback freezes and start-up delay of the streamed video at the destination vehicle by tuning the MAC retransmission limit with respect to channel statistics as well as packet transmission rate, is applied at road side unit (RSU). Two-hop transmission is applied in zones in which the destination vehicle is not within the transmission range of any RSU. In the multi-hop scenario, we discuss the computation of access probability used in the MAC adaptation scheme and propose a cross-layer path selection scheme; 2) We take advantage of similarity between multi-hop urban VANETs in dense traffic conditions and mesh connected networks. First, we investigate an application-centric routing scheme for video streaming over mesh connected overlays. Next, we introduce the challenges of urban VANETs compared to mesh networks and extend the proposed scheme in mesh network into a protocol for urban VANETs. A classification-based method is proposed to select an optimal path for video streaming over multi-hop mesh networks. The novelty is to translate the path selection over multi-hop networks to a standard classification problem. The classification is based on minimizing average video packet distortion at the receiving nodes. The classifiers are trained offline using a vast collection of video sequences and wireless channel conditions in order to yield optimal performance during real time path selection. Our method substantially reduces the complexity of conventional exhaustive optimization methods and results in high quality (low distortion). Next, we propose an application-centric routing scheme for real-time video transmission over urban multi-hop vehicular ad-hoc network (VANET) scenarios. Queuing based mobility model, spatial traffic distribution and prob- ability of connectivity for sparse and dense VANET scenarios are taken into consideration in designing the routing protocol. Numerical results demonstrate the gain achieved by the proposed routing scheme versus geographic greedy forwarding in terms of video frame distortion and streaming start-up delay in several urban communication scenarios for various vehicle entrance rate and traffic densities; and 3) finally, the proposed quality-driven routing scheme for delivering video streams is combined with a novel IP management scheme. The routing scheme aims to optimize the visual quality of the transmitted video frames by minimizing the distortion, the start-up delay, and the frequency of the streaming freezes. As the destination vehicle is in motion, it is unrealistic to assume that the vehicle will remain connected to the same access router (AR) for the whole trip. Mobile IP management schemes can benefit from the proposed multi-hop routing protocol in order to adapt proxy mobile IPv6 (PMIPv6) for multi-hop VANET for video streaming applications. The proposed cross-layer protocols can significantly improve the video streaming quality in terms of the number of streaming freezes and start-up delay over VANETs while achieving low computational complexity by using pattern classification methods for optimization.
254

SPLITS Stream Handlers: Deploying Application-level Services to Attached Network Processor

Gavrilovska, Ada 12 July 2004 (has links)
Modern distributed applications utilize a rich variety of distributed services. Due to the computation-centric notions of modern machines, application-level implementations of these services are problematic for applications requiring high data transfer rates, for reasons that include the inability of modern architectures to efficiently execute computations with communication. Conversely,network-level implementations of services are limited due to the network's inability to interpret application-level data or execute application-level operations on such data. The emergence of programmable network processors capable of high-rate data transfers, with flexible interfaces for external reconfiguration, has created new possibilities for movement of processing into the network infrastructure. This thesis explores the extent to which programmable network processors can be used in conjunction with standard host nodes, to form enhanced computational host-ANP (Attached Network Processor) platforms that can deliver increased efficiency for variety of applications and services. The main contributions of this research are the creation of SPLITS, a Software architecture for Programmable LIghtweighT Stream handling, and its key abstraction stream handlers. SPLITS enables the dynamic configuration of data paths through the host-ANP nodes, and the dynamic creation, deployment and reconfiguration of application-level processing applied along these paths. With SPLITS, application-specific services can be dynamically mapped to the host, ANP, or both, to best exploit their joint capabilities. The basic abstraction used by SPLITS to represent instances of application-specific activities are stream handlers - parameterizable, lightweight, computation units that operate on data headers as well as application-level content. Experimental results demonstrate performance gains of executing various application-level services on ANPs, and demonstrate the importance of the SPLITS host-ANP nodes to support dynamically reconfigurable services, and to deal with the resource limitations on the ANPs.
255

Supporting Scalable and Resilient Video Streaming Applications in Evolving Networks

Guo, Meng 24 August 2005 (has links)
While the demand for video streaming services has risen rapidly in recent years, supporting video streaming service to a large number of receivers still remains a challenging task. Issues of video streaming in the Internet, such as scalability, and reliability are still under extensive research. Recently proposed network contexts such as overlay networks, and mobile ad hoc networks pose even tougher challenges. This thesis focuses on supporting scalable video streaming applications under various network environments. More specifically, this thesis investigates the following problems: i) Server selection in replicated batching video on demand (VoD) systems: we find out that, to optimize the user perceived latency, it is vital to consider the server state information and channel allocation schemes when making server selection decisions. We develop and evaluate a set of server selection algorithms that use increasingly more information. ii) Scalable live video streaming with time shifting and video patching: we consider the problem of how to enable continuous live video streaming to a large group of clients in cooperative but unreliable overlay networks. We design a server-based architecture which uses a combined technique of time-shifting video server and P2P video patching. iii) A Cooperative patching architecture in overlay networks: We design a cooperative patching architecture which shifts video patching responsibility completely to the client side. An end-host retrieves lost data from other end-hosts within the same multicast group. iv) V3: a vehicle to vehicle video streaming architecture: We propose V3, an architecture to provide live video streaming service to driving vehicles through vehicle-to-vehicle (V2V) networks. V3 incorporates a novel signaling mechanism to continuously trigger video sources to send video data back to the receiver. It also adopts a store-carry-and-forward approach to transmit video data in a partitioned network environment. We also develop a multicasting framework that enables live video streaming applications from multiple sources to multiple receivers in V2V networks. A message integration scheme is used to suppress the signaling overhead, and a two-level tree-based routing approach is adopted to forward the video data.
256

Implementation of Action Recognition Algorithm on Multiple-Streaming Multimedia Unit

Lin, Tzu-chun 03 August 2010 (has links)
Action recognition had become prosperous in development and been broadly applied in several sectors. From homeland security, personal property, home caring, even the smart environment and the motion-sensing games, are in its territories This paper analysis the algorithm of Action recognition for embedded system, finds that there are many blocks can use the parallel execution to compute more efficiently. This paper tries to implement action recognition algorithm on Multiple-Streaming Multimedia Unit (MSMU). MSMU is a MMX-like SIMD architecture, with SIMD Operation and Data Storage. By introduction the concept of multiple streaming, MSMU will be able to modulate the amount of parallel data streams dynamically via switching the instruction mode. With Mode Switching and new added transfer instruction to compute 2D image processing, study the benefit of the instruction mode switching Through comparing the 128-bit SSE architecture and MSMU architecture with the practical example, highlight the problems that exploiting the subword parallelisms facing and bring out the advantage of Multistreaming. For the algorithm, study the slicing the minimum element and using the bitwise operation approach to better efficiency. Compare to embedded SIMD architecture "WMMX", MSMU can achieve 3.49¡Ñ overall speedup.
257

Evaluation of Probabilistic Early Response TCP (PERT) for Video Delivery and Extension with ACK Coalescing

Qian, Bin 2011 August 1900 (has links)
This thesis demonstrates the performance of Probabilistic Early Response TCP (PERT), a new TCP congestion control, for video streaming. As a delay based protocol, it measures the delay at the end host and adjusts the congestion window accordingly. Our experiments show that PERT improves video delivery performance by decreasing the fraction of packets delivered late. Furthermore, our Linux live streaming test indicates that PERT is able to reduce the playback glitches, when high resolution video is delivered over a link with non-zero packet loss. In order to operate PERT at higher thoughputs, we design PERT to work with Acknowledgement (ACK) coalescing at the receiver. ACK coalescing makes data transfers burstier and makes it hard to estimate delays accurately. We apply TCP pacing to fix this issue, and validate its effectiveness in the aspects of throughput, packet loss and fairness. Our experiment results also show that PERT with Delayed ACK and Pacing is more friendly, and therefore more suitable when multiple traffic flows are competing for limited bottleneck bandwidth or sharing the same router buffer.
258

Development of the method in multimedialization of Environmental science and technology courses

T.J. Juang, Simon 26 June 2003 (has links)
This purpose of this study was to develop the method in multimedia of environmental science and technology courses. The advanced net-work streaming technology was presented to edit the environmental science and technology courses. A development method combined vision technology and engineering experiments was to fulfill the eport of multimedia. In this work, we found (1) the interrelating ability of editing soft wares in production of above courses was very important; (2) to make a satisfactory works, a balancing decision was need between expected good result and limited budget; (3) as for net-work wide frequency extended and soft ware technology developed, the designer of courses must be careful the upgrade in editing soft wares in order to increase the courses broadcast; (4) used the practical teaching in topics, it could be training the real operation and resolving ability in problem on students; (5) a unique method correlated the record in experiment procedures to be a final report by vision technology; (6)presented a vision in multimedia of report to the project offer, to increase the trust and responsibility for works.
259

Implementation of face detection algorithm with parallel extended-MMX instruction set

Tzeng, Hua-Yi 20 August 2008 (has links)
Face detection has many applications in technical area. We think about accuracy and regular arrangement of data of face detection. So, we select Recognition algorithms using neural network for implementation. The implementation method can be divided into three parts. One is Modified Census Transform. The other one is computing hypotheses. Other is square frame for mark face. Modified Census Transform is a regularly computing method and regular arrangement of data. Modified Census Transform is compatible using SIMD execution, but other parts is irregular arrangement of data and not easy to parallel execution. This paper uses SIMD processor architecture which develops in our laboratory to implementation of Modified Census Transform and multi-data streaming property. The picture is divided four parts to execute at the same time and changes different mode to execute according to different algorithm then fetch data is smooth and moving data can reduce frequency. Adding a new instruction that uses 16bits data format uses four MMX registers for 4¡Ñ4 transpose of the matrix. The other is loading data and extending signed bit or unsigned bit at the same time. They can accelerate parallel execution in multi-data streaming. We also support multi-data streaming that is not series. It uses striping mode to fetch multi-data which between the same distance then we can achieve to compute multi-data streaming. Besides, we use hypotheses to distinguish different person that we only want find one. We compare two hypotheses. If the difference in hypotheses between two different picture that there is small than 0.3%, they are the same person which in different picture. Finial, we verify the function is correct in UMVP-2500 platform. We compare efficiency with MMX and Xscale and analysis multi-data streaming SIMD architecture which has some benefits. We compare efficiency with MMX. We speed up 373%. We compare efficiency with Xscale. We speed up 345%. This result will show that multi-data streaming SIMD architecture compares speed up with others SIMD architecture. Multi-data streaming SIMD architecture adds a new instruction which is 4¡Ñ4 transpose of the matrix. Because the 4¡Ñ4 transpose of the matrix can change row and column, we have new abstraction. The common computation likes a line, but the new abstraction becomes a phase. MMX and Xscale are not this abstraction.
260

Smart-Fit: Peer-to-Peer Topology Construction Strategy for Live Video Streaming towards Minimized Delay

Chang, Chun-hao 18 July 2009 (has links)
Due to the fast growing bandwidth of Internet users, the P2P video streaming on the Internet becomes one of impaortant solutions to release the traffic load. However, the current studies fall short of addressing the video delay issue on live P2P streaming. In this research, we proposed a topology construction method: Smart-Fit, towards minimizing the transmission delay between users and video server. The concept is based on minimizing the hop counts between server and users, in further to reduce the delay. With the bandwidth variety of Internet users, the proppsed method builds a predicted ideal template. Then the users¡¦ joining and leaving behaviors and the system¡¦s topology are constructed according to the template. Simulation results show the proposed method successfully reduces the hop count and the transmission delay between users and server. Moreover, due to the reduction of hop count, the packet loss rate is also reduced.

Page generated in 0.0893 seconds