Video streaming

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THE USE OF VIDEO IN TEACHING SPEAKING NARRATIVE TEXT: A Quasi Experimental at a State Senior High School in Bandung

This study aimed to find out the effectiveness of using video in teaching speaking narrative text and find out the students’ perception on the use of video on it. This study used a quasi-experimental design, the experimental group (N=30) and the control group (N=30). It was conducted in a state senior high school in Bandung with 60 sample students of eleventh graders. Both groups were given pre-test before treatment, and post-test after treatment. The experimental group was treated by video, while the control group was treated without video. In collecting the data, the researcher used pre-test, post-test and questionnaire. The data gained from pre-test and post-test then were analyzed by using t-test SPSS version 16.0. The data from posttest showed that the posttest value of t obt is -3.976, and the significant value (2 tailed) is .000. Since the significant value is lower than .05 ( Sig < .05), so the null hypothesis is rejected. It means that there is a significant difference between posttests of the experimental group and the control group. The questionnaire consisted of 15 closed questions. It was about three aspects of perception: affective, cognitive, and behaviour. The data from questionnaire showed that most students gave positive perception on the use of video in teaching speaking narrative text. From the result, it can be concluded that the use of video can improve students speaking competence especially in comprehending narrative text and video has been positively appreciated by most students. Penelitian ini bertujuan untuk mengetahui keefektifan penggunaan video dalam mengajarkan teks narasi yang di ucapkan dan persepsi para siswa terhadap penggunaan video tersebut.Penelitian ini menggunakan desain qwasi experimen dengan jumal 30 siswa pada grup eksperimen dan 30 siswa pada grup kontrol. Penelitian ini dilakukan pada salah satu SMAN di Bandung dengan jumlah 60 siswa kelas 11. Kedua grup tersebut diberikan pretest sebelum diberikan treatment. Setelah itu, mereka diberikan posttes. Grup eksperimen diberikan treatment menggunakan media video, sedangkan untuk grup kontrol diberikan treatment tanpa menggunakan media video. Dalam pengumpulan data, peneliti menggunakan pre-test, post-test dan kuesioner. Data yang didapatkan dari pre-test dan post-test, selanjutnya dianalisa menggunakan uji t SPSS versi 16.0. Data dari posttest menunjukkan bahwa nilai t obt adalah -3.976, dan nilai signifikansi (2 arah) adalah .000. ketika nilai signifikansi lebih rendah dari .05 ( Sig < .05), maka null hypothesis ditolak. Itu artinya terdapat sebuah perbedaan yang signifikan diantara posttest dari kedua grup tersebut. Kuesioner terdiri dari is pertanyaan yang tertutup. Pertanyaan itu terdiri dari 3 aspek persepsi: affective, cognitive, dan behaviour. Data dari kuesioner menunjukkan bahwa kebanyak sisa memberikan persepsi positif terhadap penggunaan video dalam mengajarkan teks narasi yang diucapkan. Dari hasil tersebut, dapat ditarik kesimpulan bahwa penggunaan video dapat mengembangkan kemampuan berbicara para siswa khususnya dalam memahami teks narasi dan video telah diapresiasi positif oleh kebanyakan para siswa

Video Quality Prediction for Video over Wireless Access Networks (UMTS and WLAN)

Transmission of video content over wireless access networks (in particular, Wireless Local Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing video quality prediction models. The main aim of the project is the development of novel and efficient models for video quality prediction in a non-intrusive way for low bitrate and resolution videos and to demonstrate their application in QoS-driven adaptation schemes for mobile video streaming applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content type was found to be the most important parameter. (3) Efficient regression-based and artificial neural network-based learning models were developed for video quality prediction over WLAN and UMTS access networks. The models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and optimization in network planning and content provisioning for network/service providers.(4) The applications of the proposed regression-based models were investigated in (i) optimization of content provisioning and network resource utilization and (ii) A new fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks. (5) Finally, Internet-based subjective tests that captured distortions caused by the encoder and the wireless access network for different types of contents were designed. The database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.Partially sponsored by EU FP7 ADAMANTIUM Project (EU Contract 214751

Perceived audiovisual quality of low-bitrate multimedia content

10.1109/TMM.2006.879871IEEE Transactions on Multimedia85973-980ITMU

Perceived Audiovisual Quality of Low-Bitrate Multimedia Content

Abstract — This paper studies the quality of multimedia content at very low bitrates. We carried out subjective experiments for assessing audiovisual, audio-only, and video-only quality. We selected content and encoding parameters that are typical of mobile applications. Our focus were the MPEG-4 AVC (a.k.a. H.264) and AAC coding standards. Based on these data, we first analyze the influence of video and audio coding parameters on quality. We investigate the optimal trade-off between bits allocated to audio and to video under global bitrate constraints. Finally, we explore models for the interactions between audio and video in terms of perceived audiovisual quality. I

Qualitätstaxonomie für skalierbare Algorithmen von Free Viewpoint Video Objekten

Diese Dissertation beabsichtigt einen Beitrag zur Qualitätsbeurteilung von Algorithmen für Bildanalyse und Bildsynthese im Anwendungskontext Videokommunikationssysteme zu leisten. In der vorliegenden Arbeit werden Möglichkeiten und Hindernisse der nutzerzentrierten Definition von subjektiver Qualitätswahrnehmung in diesem speziellen Anwendungsfall untersucht. Qualitätsbeurteilung von aufkommender Visualisierungs-Technologie und neuen Verfahren zur Erzeugung einer dreidimensionalen Repräsentation unter der Nutzung von Bildinformation zweier Kameras für Videokommunikationssysteme wurde bisher noch nicht umfangreich behandelt und passende Ansätze dazu fehlen. Die Herausforderungen sind es qualitätsbeeinflussende Faktoren zu definieren, passende Maße zu formulieren, sowie die Qualitätsevaluierung mit den Erstellungsalgorithmen, welche noch in Entwicklung sind, zu verbinden. Der Vorteil der Verlinkung von Qualitätswahrnehmung und Servicequalität ist die Unterstützung der technischen Realisierungsprozesse hinsichtlich ihrer Anpassungsfähigkeit (z.B. an das vom Nutzer verwendete System) und Skalierbarkeit (z.B. Beachtung eines Aufwands- oder Ressourcenlimits) unter Berücksichtigung des Endnutzers und dessen Qualitätsanforderungen. Die vorliegende Arbeit beschreibt den theoretischen Hintergrund und einen Vorschlag für eine Qualitätstaxonomie als verlinkendes Modell. Diese Arbeit beinhaltet eine Beschreibung des Projektes Skalalgo3d, welches den Rahmen der Anwendung darstellt. Präsentierte Ergebnisse bestehen aus einer systematischen Definition von qualitätsbeeinflussenden Faktoren inklusive eines Forschungsrahmens und Evaluierungsaktivitäten die mehr als 350 Testteilnehmer inkludieren, sowie daraus heraus definierte Qualitätsmerkmale der evaluierten Qualität der visuellen Repräsentation für Videokommunikationsanwendungen. Ein darauf basierendes Modell um diese Ergebnisse mit den technischen Erstellungsschritten zu verlinken wird zum Schluss anhand eines formalisierten Qualitätsmaßes präsentiert. Ein Flussdiagramm und ein Richtungsfeld zur grafischen Annäherung an eine differenzierbare Funktion möglicher Zusammenhänge werden daraufhin für weitere Untersuchungen vorgeschlagen.The thesis intends to make a contribution to the quality assessment of free viewpoint video objects within the context of video communication systems. The current work analyzes opportunities and obstacles, focusing on users' subjective quality of experience in this special case. Quality estimation of emerging free viewpoint video object technology in video communication has not yet been assessed and adequate approaches are missing. The challenges are to define factors that influence quality, to formulate an adequate measure of quality, and to link the quality of experience to the technical realization within an undefined and ever-changing technical realization process. There are two advantages of interlinking the quality of experience with the quality of service: First, it can benefit the technical realization process, in order to allow adaptability (e.g., based on systems used by the end users). Second, it provides an opportunity to support scalability in a user-centered way, e.g., based on a cost or resources limitation. The thesis outlines the theoretical background and introduces a user-centered quality taxonomy in the form of an interlinking model. A description of the related project Skalalgo3d is included, which offered a framework for application. The outlined results consist of a systematic definition of factors that influence quality, including a research framework, and evaluation activities involving more than 350 participants. The thesis includes the presentation of quality features, defined by evaluations of free viewpoint video object quality, for video communication application. Based on these quality features, a model that links these results with the technical creation process, including a formalized quality measure, is presented. Based on this, a flow chart and slope field are proposed. These intend the visualization of these potential relationships and may work as a starting point for further investigations thereon and to differentiate relations in form of functions

Contribución a los modelos de estimación de la calidad percibida en servicios de vídeo sobre Internet mediante parámetros objetivos

En los últimos años el consumo de servicios de vídeo se ha incrementado de forma notable y se espera que dicha tendencia continúe en los próximos años. Los servicios de streaming de vídeo Over-The-Top (OTT), en los que se centra esta tesis, constituyen uno de los principales motores de dicho crecimiento. A diferencia de los servicios Internet Protocol Television (IPTV), que utilizan una red controlada en la que se pueden implementar mecanismos de Quality of Service (QoS), los servicios de streaming de vídeo OTT se prestan sobre Internet, por lo que llevan asociados interesantes desafíos desde un punto de vista técnico. Uno de los mayores desafíos técnicos a los que se enfrentan los servicios de streaming de vídeo OTT es mantener un nivel de Quality of Experience (QoE) que satisfaga a sus usuarios, por lo que es necesario contar con técnicas y herramientas que permitan monitorizar la calidad percibida por los usuarios de estos servicios. El streaming de vídeo OTT supone un cambio de filosofía en comparación con otras técnicas de streaming más tradicionales como RTP/RTSP. Los servicios de vídeo OTT suelen seguir el paradigma Dynamic Adaptive Streaming over HTTP (DASH), que se basa en sustituir los servidores de streaming tradicionales por servidores web que ponen a disposición de los clientes los contenidos de vídeo codificados en varias versiones con distinto nivel de calidad. Cada una de estas versiones o representaciones está dividida en pequeños fragmentos o segmentos que los clientes pueden solicitar mediante el protocolo HTTP. Los clientes pueden solicitar diferentes niveles de calidad en función de los parámetros que consideren más adecuados (ancho de banda de la red, resolución de pantalla, tipo de códec, etc.), lo que les permite adaptarse a condiciones cambiantes del entorno. Como se puede ver, el paradigma DASH ha trasladado el control de la sesión del servidor al cliente y ha sustituido los servidores de streaming por servidores web que simplemente sirven los segmentos de vídeo que los clientes solicitan. Además se esta simplificación de los servidores de streaming, existen otras ventajas asociadas a DASH, como son la utilización de Content Delivery Network (CDN), la compatibilidad con NATs y firewalls, etc. En esta tesis doctoral se lleva a cabo la propuesta de un conjunto de modelos cuyo objetivo es estimar la calidad percibida por los usuarios de los servicios de vídeo basados en DASH. Más concretamente, partiendo de la definición del servicio como un conjunto de componentes de servicio, se desarrollan modelos parciales que estiman la calidad percibida asociada a cada uno de estos componentes: calidad de vídeo, calidad de audio, degradaciones asociadas a la transmisión, etc. Cada una de estas estimaciones de calidad percibida se combinan en un modelo global que estima la calidad percibida total del servicio

Quality of experience in digital mobile multimedia services

People like to consume multimedia content on mobile devices. Mobile networks can deliver mobile TV services but they require large infrastructural investments and their operators need to make trade-offs to design worthwhile experiences. The approximation of how users experience networked services has shifted from the inadequate packet level Quality of Service (QoS) to the user perceived Quality of Experience (QoE) that includes content, user context and their expectations. However, QoE is lacking concrete operationalizations for the visual experience of content on small, sub-TV resolution screens displaying transcoded TV content at low bitrates. The contribution of my thesis includes both substantive and methodological results on which factors contribute to the QoE in mobile multimedia services and how. I utilised a mix of methods in both lab and field settings to assess the visual experience of multimedia content on mobile devices. This included qualitative elicitation techniques such as 14 focus groups and 75 hours of debrief interviews in six experimental studies. 343 participants watched 140 hours of realistic TV content and provided feedback through quantitative measures such as acceptability, preferences and eye-tracking. My substantive findings on the effects of size, resolution, text quality and shot types can improve multimedia models. My substantive findings show that people want to watch mobile TV at a relative size (at least 4cm of screen height) similar to living room TV setups. In order to achieve these sizes at 35cm viewing distance users require at least QCIF resolution and are willing to scale it to a much lower angular resolution (12ppd) then what video quality research has found to be the best visual quality (35ppd). My methodological findings suggest that future multimedia QoE research should use a mixed methods approach including qualitative feedback and viewing ratios akin to living room setups to meet QoE’s ambitious scope