Iñigo Sedano

Analysis and characterization of IPTV user behavior

Today, due to the fast development of Internet Protocol TV (IPTV), which is the combination of IP technology and two-way broadband networks, the telecom industry is undergoing fundamental changes. Network operators and service providers around the world are making significant investments in order to deliver digital video content to their subscribers. Video puts very high demands on the network and utilizes a large fraction of the available bandwidth. Consequently, it is important to understand the technical demands that IPTV requires of the network infrastructure as well as user behavior and network traffic patterns to further optimize network operation. The purpose of this paper is to characterize IPTV traffic and study end user behavior by analyzing and modeling IPTV traffic collected from a Swedish municipal network. The focus of the measurements was put on Internet Group Management Protocol (IGMP) packets. Apart from the measurement results and analysis, the paper provides background information about the technologies and issues of IPTV. IP multicast which is used for transferring Live TV content is based on the concept of a group. IGMP is used to manage the membership of multicast groups. Based on this information, traffic parameters for analysis were chosen and measured.

Standardized toolchain and model development for video quality assessment — The mission of the Joint Effort Group in VQEG

Since 1997, the Video Quality Experts Group (VQEG) has been active in the field of subjective and objective video quality assessment. The group has validated competitive quality metrics throughout several projects. Each of these projects requires mandatory actions such as creating a testplan and obtaining databases consisting of degraded video sequences with corresponding subjective quality ratings. Recently, VQEG started a new open initiative, the Joint Effort Group (JEG), for encouraging joint collaboration on all mandatory actions needed to validate video quality metrics. Within the JEG, effort is made to advance the field of both subjective and objective video quality measurement by providing proper software tools and subjective databases to the community. One of the subprojects of the JEG is the joint development of a hybrid H.264/AVC objective quality metric. In this paper, we introduce the JEG and provide an overview of the different ongoing activities within this newly started group.

Full-reference video quality metric assisted the development of no-reference bitstream video quality metrics for real-time network monitoring

High-quality video is being increasingly delivered over Internet Protocol networks, which means that network operators and service providers need methods to measure the quality of experience (QoE) of the video services. In this paper, we propose a method to speed up the development of no-reference bitstream objective metrics for estimating QoE. This method uses full-reference objective metrics, which makes the process significantly faster and more convenient than using subjective tests. In this process, we have evaluated six publicly available full-reference objective metrics in three different databases, the EPFL-PoliMI database, the HDTV database, and the Live Video Wireless database, all containing transmission distortions in H.264 coded video. The objective metrics could be used to speed up the development process of no-reference real-time video QoE monitoring methods that are receiving great interest from the research community. We show statistically that the full-reference metric Video Quality Metric (VQM) performs best considering all the databases. In the EPFL-PoliMI database, SPATIAL MOVIE performed best and TEMPORAL MOVIE performed worst. When transmission distortions are evaluated, using the compressed video as the reference provides greater accuracy than using the uncompressed original video as the reference, at least for the studied metrics. Further, we use VQM to train a lightweight no-reference bitstream model, which uses the packet loss rate and the interval between instantaneous decoder refresh frames, both easily accessible in a video quality monitoring system.

Evaluation of video quality metrics on transmission distortions in H.264 coded video

The development of high-speed access networks has enabled a variety of video delivery alternatives over the Internet, for example IPTV and peer-to-peer based video services as Voddler. Consequently, the development of real-time video QoE monitoring methods is receiving large attention in the research community. We believe that the good performing objective metrics using reference information could be used to speed up the development process of real-time video QoE monitoring methods. Thus in this paper we study the accuracy of full-reference objective methods for assessing the quality degradation due to the transmission distortions. We evaluated several well-known publicly-available full-reference objective metrics on the freely available EPFL-PoliMI (Ecole Polytechnique Fédérale de Lausanne and Politecnico di Milano) video quality assessment database, which was specifically designed for the evaluation of transmission distortions. The full-reference metrics are usually evaluated using a reference which is uncompressed. Instead, we study the performance of the metrics when the reference videos are lightly compressed to ensure high quality.

Hybrid video quality prediction: reviewing video quality measurement for widening application scope

A tremendous number of objective video quality measurement algorithms have been developed during the last two decades. Most of them either measure a very limited aspect of the perceived video quality or they measure broad ranges of quality with limited prediction accuracy. This paper lists several perceptual artifacts that may be computationally measured in an isolated algorithm and some of the modeling approaches that have been proposed to predict the resulting quality from those algorithms. These algorithms usually have a very limited application scope but have been verified carefully. The paper continues with a review of some standardized and well-known video quality measurement algorithms that are meant for a wide range of applications, thus have a larger scope. Their individual artifacts prediction accuracy is usually lower but some of them were validated to perform sufficiently well for standardization. Several difficulties and shortcomings in developing a general purpose model with high prediction performance are identified such as a common objective quality scale or the behavior of individual indicators when confronted with stimuli that are out of their prediction scope. The paper concludes with a systematic framework approach to tackle the development of a hybrid video quality measurement in a joint research collaboration.

Application of full-reference video quality metrics in IPTV

Executing an accurate full-reference metric such as VQM can take minutes in an average computer for just one user. Therefore, it can be unfeasible to analyze all the videos received by users in an IPTV network for example consisting of 10.000 users using a single computer running the VQM metric. One solution can be to use a lightweight no-reference metrics in addition to the full-reference metric mentioned. Lightweight no-reference metrics can be used for discarding potential situations to evaluate because they are accurate enough for that task, and then the full-reference metric VQM can be used when more accuracy is needed. The work in this paper is focused on determining the maximum number of situations/users that can be analyzed simultaneously using the VQM metric in a computer with good performance. The full-reference metric is applied on the transmitter using a method specified in the recommendation ITU BT.1789. The best performance achieved was 112.8 seconds per process.