Video streaming applications over wireless networks have turned out to be immensely popular recently. In this thesis, we first study the buffering schemes for the VBR video streaming in heterogeneous wireless networks. An analytical framework is presented to derive the expected number of jitters and average buffering delay. Through experimenting with a wide range of buffering schemes, we quantify the bene¯t of incorporating user location information in streaming over heterogeneous wireless networks. Second, we consider the delivery of scalable VBR video streams over wireless channels. We propose adaptive rate control algorithms to improve the combined system performance of video frame quality and playout smoothness based on the feedback information of wireless network estimation, buffer content and playback situation. The proposed adaptive rate control algorithms provide significantly improved streaming quality compared with the non-control policy.

All major semiconductor companies are now shipping multi-cores. Phones, PCs, laptops, and mobile internet devices will all require software that can make effective use of these cores. Writing high-performance parallel software is difficult, time-consuming and error prone, increasing both time-to-market and cost. Software outlives hardware; it typically takes longer to develop new software than hardware, and legacy software tends to survive for a long time, during which the number of cores per system will increase. Development and maintenance productivity will be improved if parallelism and technical details are managed by the machine, while the programmer reasons about the application as a whole. Parallel software should be written using domain-specific high-level languages or extensions. These languages reveal implicit parallelism, which would be obscured by a sequential language such as C. When memory allocation and program control are managed by the compiler, the program's structure and data layout can be safely and reliably modified by high-level compiler transformations. One important application domain contains so-called stream programs, which are structured as independent kernels interacting only through one-way channels, called streams. Stream programming is not applicable to all programs, but it arises naturally in audio and video encode and decode, 3D graphics, and digital signal processing. This representation enables high-level transformations, including kernel unrolling and kernel fusion. This thesis develops new compiler and run-time techniques for stream programming. The first part of the thesis is concerned with a statically scheduled stream compiler. It introduces a new static partitioning algorithm, which determines which kernels should be fused, in order to balance the loads on the processors and interconnects. A good partitioning algorithm is crucial if the compiler is to produce efficient code. The algorithm also takes account of downstream compiler passes---specifically software pipelining and buffer allocation---and it models the compiler's ability to fuse kernels. The latter is important because the compiler may not be able to fuse arbitrary collections of kernels. This thesis also introduces a static queue sizing algorithm. This algorithm is important when memory is distributed, especially when local stores are small. The algorithm takes account of latencies and variations in computation time, and is constrained by the sizes of the local memories. The second part of this thesis is concerned with dynamic scheduling of stream programs. First, it investigates the performance of known online, non-preemptive, non-clairvoyant dynamic schedulers. Second, it proposes two dynamic schedulers for stream programs. The first is specifically for one-dimensional stream programs. The second is more general: it does not need to be told the stream graph, but it has slightly larger overhead. This thesis also introduces some support tools related to stream programming. StarssCheck is a debugging tool, based on Valgrind, for the StarSs task-parallel programming language. It generates a warning whenever the program's behaviour contradicts a pragma annotation. Such behaviour could otherwise lead to exceptions or race conditions. StreamIt to OmpSs is a tool to convert a streaming program in the StreamIt language into a dynamically scheduled task based program using StarSs. / Totes les empreses de semiconductors produeixen actualment multi-cores. Mòbils,PCs, portàtils, i dispositius mòbils d’Internet necessitaran programari quefaci servir eficientment aquests cores. Escriure programari paral·lel d’altrendiment és difícil, laboriós i propens a errors, incrementant tant el tempsde llançament al mercat com el cost. El programari té una vida més llarga queel maquinari; típicament pren més temps desenvolupar nou programi que noumaquinari, i el programari ja existent pot perdurar molt temps, durant el qualel nombre de cores dels sistemes incrementarà. La productivitat dedesenvolupament i manteniment millorarà si el paral·lelisme i els detallstècnics són gestionats per la màquina, mentre el programador raona sobre elconjunt de l’aplicació.El programari paral·lel hauria de ser escrit en llenguatges específics deldomini. Aquests llenguatges extrauen paral·lelisme implícit, el qual és ocultatper un llenguatge seqüencial com C. Quan l’assignació de memòria i lesestructures de control són gestionades pel compilador, l’estructura iorganització de dades del programi poden ser modificades de manera segura ifiable per les transformacions d’alt nivell del compilador.Un dels dominis de l’aplicació importants és el que consta dels programes destream; aquest programes són estructurats com a nuclis independents queinteractuen només a través de canals d’un sol sentit, anomenats streams. Laprogramació de streams no és aplicable a tots els programes, però sorgeix deforma natural en la codificació i descodificació d’àudio i vídeo, gràfics 3D, iprocessament de senyals digitals. Aquesta representació permet transformacionsd’alt nivell, fins i tot descomposició i fusió de nucli.Aquesta tesi desenvolupa noves tècniques de compilació i sistemes en tempsd’execució per a programació de streams. La primera part d’aquesta tesi esfocalitza amb un compilador de streams de planificació estàtica. Presenta unnou algorisme de partició estàtica, que determina quins nuclis han de serfusionats, per tal d’equilibrar la càrrega en els processadors i en lesinterconnexions. Un bon algorisme de particionat és fonamental per tal de queel compilador produeixi codi eficient. L’algorisme també té en compte elspassos de compilació subseqüents---específicament software pipelining il’arranjament de buffers---i modela la capacitat del compilador per fusionarnuclis. Aquesta tesi també presenta un algorisme estàtic de redimensionament de cues.Aquest algorisme és important quan la memòria és distribuïda, especialment quanles memòries locals són petites. L’algorisme té en compte latències ivariacions en els temps de càlcul, i considera el límit imposat per la mida deles memòries locals.La segona part d’aquesta tesi es centralitza en la planificació dinàmica deprogrames de streams. En primer lloc, investiga el rendiment dels planificadorsdinàmics online, non-preemptive i non-clairvoyant. En segon lloc, proposa dosplanificadors dinàmics per programes de stream. El primer és específicament pera programes de streams unidimensionals. El segon és més general: no necessitael graf de streams, però els overheads són una mica més grans.Aquesta tesi també presenta un conjunt d’eines de suport relacionades amb laprogramació de streams. StarssCheck és una eina de depuració, que és basa enValgrind, per StarSs, un llenguatge de programació paral·lela basat en tasques.Aquesta eina genera un avís cada vegada que el comportament del programa estàen contradicció amb una anotació pragma. Aquest comportament d’una altra manerapodria causar excepcions o situacions de competició. StreamIt to OmpSs és unaeina per convertir un programa de streams codificat en el llenguatge StreamIt aun programa de tasques en StarSs planificat de forma dinàmica.

SVT is Sweden’s largest TV-network and broadcasts more then 22 000 hours of TV each year. SVT is a public service company where the basic idea is to reflect the world from different perspectives and news is very important for providing neutral and versatile information in a variety of areas. An important part of the flow of information is to continuously receive reports from all corners of the world around the clock. This places very high demands on the technology used and it is important that it function and develops to meet current and future growing needs. One of SVTs vision is to increase the proportion of live reports in news broadcasts and self produced news reports from remote locations and is therefore interested in new technologies that offer greater topicality and lower cost for the reports. There are two different technologies used in the present situation, Store and Forward and Live. The difference between them is that at the Store and Forward the reporter sends a complete edited feature back to the news room. When doing a Live the reporter simply performs a live reporting. During the project a technical comparison between today’s products has been performed, the comparison has highlighted advantages and disadvantages of these products video and audio coding and data transmission. Even a comparison of their ease of use and functionality has been conducted and results are to be the basis for a set of requirements for additional procurement of large scale purchases of new systems. The results have shown that the system from the English company Quicklink is the one that performs best image quality overall for both Store and Forward and Live. The system has a well working interface with many smart features and is also easy to use in a large scale environment. All these features make the application from Quicklink best suited for SVTs needs.

This qualitative case-study research investigated how Eastern European immigrant youth in a southern English public secondary school adjusted to and experienced the British educational system, which involves streaming students into levels of academic ability. The study focused on these students experiences of day-to-day life in a British secondary school and it explored the challenges and successes that they experienced. The study also investigated the experiences of teachers and administrators involved in the education of immigrant students. Through the use of student and faculty experiences, through recorded interviews, this study sought to understand how educators could improve the ways they are educating immigrant students.

No description available.

Delivering high-quality of video to end users over the best-effort Internet is a challenging task since quality of streaming video is highly subject to network conditions. A fundamental issue in this area is how real-time applications cope with network dynamics and adapt their operational behavior to offer a favorable streaming environment to end users. As an effort towards providing such streaming environment, the first half of this work focuses on analyzing the performance of video streaming in best-effort networks and developing a new streaming framework that effectively utilizes unequal importance of video packets in rate control and achieves a near-optimal performance for a given network packet loss rate. In addition, we study error concealment methods such as FEC (Forward-Error Correction) that is often used to protect multimedia data over lossy network channels. We investigate the impact of FEC on the quality of video and develop models that can provide insights into understanding how inclusion of FEC affects streaming performance and its optimality and resilience characteristics under dynamically changing network conditions. In the second part of this thesis, we focus on measuring bandwidth of network paths, which plays an important role in characterizing Internet paths and can benefit many applications including multimedia streaming. We conduct a stochastic analysis of an end-to-end path and develop novel bandwidth sampling techniques that can produce asymptotically accurate capacity and available bandwidth of the path under non-trivial cross-traffic conditions. In addition, we conduct comparative performance study of existing bandwidth estimation tools in non-simulated networks where various timing irregularities affect delay measurements. We find that when high-precision packet timing is not available due to hardware interrupt moderation, the majority of existing algorithms are not robust to measure end-to-end paths with high accuracy. We overcome this problem by using signal de-noising techniques in bandwidth measurement. We also develop a new measurement tool called PRC-MT based on theoretical models that simultaneously measures the capacity and available bandwidth of the tight link with asymptotic accuracy.

Multimedia streaming is one of the killer applications for cellular communications. Although the 3GPP proposes the Packet-Switched Streaming (PSS) protocol to support the multimedia streaming services, the performances are still not good enough. To improve the performances, most of the researches divide the cellular networks into two parts: the wired network and the wireless network, and focus on the wireless network part. Hence the adaptive streaming was proposed. It utilizes the RTCP feedback in RTP to monitor the wireless network, and makes appropriate transmission parameters adjustments to prevent from buffer underflow and packet loss. But the overall performance may not be only limited by the wireless network part. Also, with high mobility, the link quality may be influenced severely by many factors. Hence, we will evaluate the performance of streaming services over 3G cellular networks on the train of Taiwan high speed railway in this paper and propose a mechanism to improve the performance.

The H.264 Protocol is an important method for the multimedia transmission and calculation, but it is difficult to work smoothly on the embedded systems because of the low clock in the working environment of the embedded system .Although many new multimedia instruction sets have been developed, the immediate multimedia calculation is still difficult to implement on the embedded system. So this paper uses the ¡§Multimedia Operation Register¡¨, a SIMD architecture, to implement H.264 algorithm on the embedded system to improve the performance of handling multimedia calculation. Multimedia Operation Register, which performs the parallel execution of the multi-data-streaming, uses the bit slice concept to design operation pair combining bit storage cell and bit computation. According to the characteristic , which is the address having constant distance between more than two data being used saved in the Memory, this paper using the striping addressing mode , which can cooperate with the parallel execution of multi-data-streaming , to load the data having strode addresses from the Memory in one instructions. On the other hand, this paper designs a new instruction set based on the Intel MMX instruction set and the operation feature of multimedia calculation. When a designer uses single-data-steaming to implement the H.264 Protocol by the multimedia instruction sets, he will use more interactions to do the same thing in every block. Now this paper can use fewer interactions to do the same thing because the Multimedia Operation Register can use the parallel execution of the multi-data-stream to calculate the data in many different blocks to implement H.264 Protocol at the same time. On the other hand, this paper can reallocate the number of the registers to the arithmetic unit which will be used smartly by changing the working mode. This paper also saves much execution time of some actions such as the transpose of the matrix, the data resorting and the SAD (Sum of Absolute Differences) calculation by using new instructions. In order to reduce the times of memory access, this paper uses the method which rotates the data between two registers to let the data been used as possible as it can. So the coding efficiency can be improved explosively by using all the methods which have been introduced. The conclusion in this paper shows that the parallel execution of the multi-data-streaming will be a very important method to handle multimedia calculation. And this paper advances an innovative architecture to implement the parallel execution of the multi-data- streaming. According to the simulation in 5th chapter, the speedup of handling H.264 Protocol by Multimedia Operation Register is more than four times with MMX instruction set. In the SAD calculation, it even can have ten times advanced then MMX instruction set. At last the efficacy is even better than the latest multimedia instruction set -¡§SSE4¡¨.

Thèse de doctorat : Informatique : Nancy 1 : 2009. / Titre provenant de l'écran-titre.

Thesis (Ph. D.)--OGI School of Science & Engineering at OHSU, 2004. / Includes bibliographical references (leaves 170-178).