Idag finns som alltid behovet att distribuera media. Allt eftersom prestandan för överföring av information i dator-nätverk har ökat har detta blivit möjligt genom streaming, strömmande media. Detta innebär att klienten inte behöver ladda ner hela materialet för att kunna se eller lyssna på det. Allt eftersom kravet på kvalitén av materialet ökar blir kraven på nätverket högre. Precisallt Media AB är ett företagsom sysslar med digital skyltning. För att nå ut med film till sina skyltar som finns i olika butiker och varuhus, schemaläggs och skickas film till en vanlig pc som sköter skylten. Lagring av video sker lokalt, det vill säga materialet som spelas upp på en skylt är lagrat på samma dator som spelar upp det. Detta är ingen effektiv lösning eftersom överföringen av material som sker över Internet måste ske till varje dator som ska spela upp det. Går det att skapa en effektivare lösning genom att använda streaming hos kunden? Och går det att effektivisera distribueringen av media tillkundens nätverk?

The purpose of this essey is through empirical methods investigate usability factors on Video On Demand applications for the Internet. More specificly we will focus on a application called Voddler. The purpose is to identify usability problems that exist in Voddler, and present the reader with suggestions on possible solutions. This could be used as guidelines to how to design for usability in this kind of system. We will use an online survey to investigate Voddler usability and use this data as a basis for our analysis. We will also conduct a expert evaluation of the system. The data collected from the survey will be compared to the expert evalutation and different theories behind usability. We will come to the conclusion that through a usability perspective Voddler has designed the software as an interactive Video On Demand service meanwhile the target audience want the application to function more like an normal computer program. This causes a conflict between the two that has to be resolved if one wants to optimize usability this kind of software.

Video feedback (VF) has been widely integrated into cognitive behavioural treatment protocols for socially anxious individuals due to its presumed efficacy in improving negative self-perception and reducing underestimations of performance. However, studies examining VF in social anxiety reveal, surprisingly, that correction of overly negative self-perception does not unequivocally facilitate anxiety reduction during subsequent social interactions. In the current study, we examined whether VF could be optimized to facilitate social anxiety reduction through the inclusion of a post-VF encoding manipulation. The manipulation was designed to enable individuals to internalize the positive information received from VF by enhancing the depth at which they processed the self-exposure information. Forty-three individuals high in social anxiety and verbal communication anxiety were randomly assigned to one of the following three conditions: A) VF + Manipulation; B) VF + No Manipulation; and C) No VF. Results revealed that VF + Manipulation led to significant cognitive changes pertaining to self-efficacy and internal attributions of performance relative to the other two conditions. Unexpectedly, both VF conditions were equally efficacious in the facilitation of anxiety reduction relative to the No VF condition. Results are discussed in the context of cognitive behavioural models of anxiety and the mechanisms of exposure-based learning.

Video feedback (VF) has been widely integrated into cognitive behavioural treatment protocols for socially anxious individuals due to its presumed efficacy in improving negative self-perception and reducing underestimations of performance. However, studies examining VF in social anxiety reveal, surprisingly, that correction of overly negative self-perception does not unequivocally facilitate anxiety reduction during subsequent social interactions. In the current study, we examined whether VF could be optimized to facilitate social anxiety reduction through the inclusion of a post-VF encoding manipulation. The manipulation was designed to enable individuals to internalize the positive information received from VF by enhancing the depth at which they processed the self-exposure information. Forty-three individuals high in social anxiety and verbal communication anxiety were randomly assigned to one of the following three conditions: A) VF + Manipulation; B) VF + No Manipulation; and C) No VF. Results revealed that VF + Manipulation led to significant cognitive changes pertaining to self-efficacy and internal attributions of performance relative to the other two conditions. Unexpectedly, both VF conditions were equally efficacious in the facilitation of anxiety reduction relative to the No VF condition. Results are discussed in the context of cognitive behavioural models of anxiety and the mechanisms of exposure-based learning.

Today’s video game players sit in front of their screens immersing themselves within the fictional environment of the video game. They connect their physical self to the game-controller and their cerebral self to the game-world. The video game medium becomes a cybernetic and psychological appendage, a prosthesis that allows game players to share their consciousness across actual and virtual realities. Such an appendage has the ability to expand the personal spatial environment of the game players as they navigate the spaces of an increasingly complex, digitally constructed extension of the imagination. The thesis begins with an autobiographical summary of personal experiences in the suburbs and the resultant escape from suburbia that video games provide. The thesis then presents a series of experiential diaries generated from gameplay. This is followed by a conceptual analysis that uses six meditations to discuss the spaces and experiences presented in the diaries. The purpose of the conceptual analysis is to investigate how the narrative and spatial experiences of single player role playing video games expand our perceptions of architecture and space beyond the real-world. The spaces of these games represent a new way of thinking about, experiencing and creating architecture.

With the technological advancement, entertainment has become revolutionized and the High-definition (HD) video has become a common feature of our modern amusement devices. Moreover, the demand for wireless transmission of HD video is rising increasingly for its ubiquitous nature, easy installation and relocation. The high bandwidth requirement is the main concern for wireless transmission of high quality video streams. Research has been going on by the consumer electronics industry to provide different solutions of this issue, for the last few years.<p> In this research work, HD video transmission feasibility using the Ultra-wideband (UWB) communication channel is analyzed. The UWB channel is selected for its short-range, high-speed data transmission capability at low-cost, and low-power consumption. The maximum transmitting range of this technology is about 10 m at 100 Mbps data rate. Simulation is conducted by controlling key parameters, such as, in-loop deblocking filter, group of pictures, and quantization parameter of an H.264/AVC encoder. Here, standard HD video streams with different motion characteristics are used, and the impact of these parameters change on the reconstructed video quality and the broadcasting data rate are analyzed. Finally, a generalized parameters settings, and a video content dependent settings for an H.264/AVC encoder are proposed for different bandwidth requirements, as well as acceptable video quality. Performance evaluation of these parameters settings is performed, and the results are quite satisfactory as long as the symbol energy to noise power density ratio, Es/No, is above 15. With the proposed parameters settings, maximum 20 Mbps data rate is achieved with 33.5 dB Y-PSNR.

The objectives of this thesis are to investigate the challenges on video streaming, to explore and compare different video streaming mechanisms, and to develop video streaming algorithms that maximize visual quality. To achieve these objectives, we first investigate scalable video multicasting schemes by comparing layered video multicasting with replicated stream video multicasting. Even though it has been generally accepted that layered video multicasting is superior to replicated stream multicasting, this assumption is not based on a systematic and quantitative comparison. We argue that there are indeed scenarios where replicated stream multicasting is the preferred approach. We also consider the problem of providing perceptually good quality of layered VBR video. This problem is challenging, because the dynamic behavior of the Internet's available bandwidth makes it difficult to provide good quality. Also a video encoded to provide a consistent quality exhibits significant data rate variability. We are, therefore, faced with the problem of accommodating the mismatch between the available bandwidth variability and the data rate variability of the encoded video. We propose an optimal quality adaptation algorithm that minimizes quality variation while at the same time increasing the utilization of the available bandwidth. Finally, we investigate the transmission control protocol (TCP) for a transport layer protocol in streaming packetized media data. Our approach is to model a video streaming system and derive relationships under which the system employing the TCP protocol achieves desired performance. Both simulation results and the Internet experimental results validate this model and demonstrate the buffering delay requirements achieve desired video quality with high accuracy. Based on the relationships, we also develop realtime estimation algorithms of playout buffer requirements.

The primary objective of this thesis is to provide a low-complexity rate-distortion optimal coding mode selection method in digital video encoding. To achieve optimal compression efficiency in the rate-distortion framework with low computational complexity, we first propose a rate-distortion model and then apply it to the coding mode selection problem. The computational complexity of the proposed method is very low compared to overall encoder complexity because the proposed method uses simple image properties such as variance that can be obtained easily. Also, the proposed method gives significant PSNR gains over the mode selection scheme used in TM5 for MPEG-2 because the rate-distortion model considers rate constraints of each mode as well as distortion. We extend the model-based mode selection approach to motion vector selection for further improvement of the coding efficiency. In addition to our theoretical work, we present practical solutions to real-time implementation of encoder modules including our proposed mode selection method on digital signal processors. First, we investigate the features provided by most of the recent digital signal processors, for example, hierarchical memory structure and efficient data transfer between on-chip and off-chip memory, and then present practical approaches for real-time implementation of a video encoder system with efficient use of the features.

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The purpose of this study was to investigate the effectiveness of two different concept mapping methods - learner-generated and expert-generated concept mapping - in computer-based video learning. The students’ attitudes toward the use of the concept mapping and computer-based instruction in general were also investigated. The study was performed using the entire enrollment of the junior level undergraduate course (n = 65) Developmental Psychology for Educators (EPSY-320) class, the spring semester of 2010 at Texas A & M University. Using experimental research design, the relationship between student achievements and learning tools was observed. The convenience sampling method was used to assign the students randomly to two treatment groups. The study built on previous research findings on the instructional use of video and concept mapping. It focused on the relative influence of expert-generated versus learner-generated concept maps on student achievement during computer-based video instruction. Results indicated that there were no significant differences among achievements of students who used either learner-generated concept maps or expert-generated concept maps in the study. However, the expert-generated concept mapping group spent significantly less time than the learner-generated concept mapping group interacting with the instructional tool. The findings revealed that concept map scores mediated the relationships between the numbers of clicks on the video player control, time spent creating concept maps, and time spent on all interaction and student achievement. Although the variables - the number of clicks on the video player control, time spent creating concept maps, and time spent on all interactions - did not have a direct effect on student achievement, they affected the concept map scores, which in turn affected student achievement. The three variables - perceived usefulness, ease of use, and attitude toward use - were used to define the attitude of the students toward the instructional tool. The results showed that the attitude of the expert-generated group toward the instructional tool was significantly higher than the learner-generated group. Also, on average, the expert-generated concept mapping group expressed neutral feelings on using the instructional tool to improve their learning performance. Alternatively, the learner-generated group did not appreciate the value of this tool. Both groups reported neutral views about the ease of use of the instructional tool. In conclusion, concept mapping might enhance cognitive learning after the basic skills are acquired and the learners become competent concept mappers. During the creation of concept maps, cognitive load might hinder student learning; therefore, students must be well trained before starting to use the learning tool. Moreover, concept map scores might be used as student grades in video-based learning.