Werner Robitza

Werner Robitza
Technische Universität Ilmenau | TUI

Dipl.-Ing.

About

56
Publications
18,749
Reads
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580
Citations
Introduction
Werner Robitza is a researcher and PhD student at the Ilmenau University of Technology in Germany. Before, he worked at Telekom Innovation Laboratories of Deutsche Telekom AG. He received his diploma degree in computer science from the University of Vienna. His research interests are Quality of Experience for multimedia applications and user behavior aspects for Web TV services.
Additional affiliations
March 2015 - present
Telekom Innovation Laboratories
Position
  • Researcher
April 2014 - February 2015
Technische Universität Berlin
Position
  • Researcher
March 2009 - December 2012
University of Vienna
Position
  • Researcher
Education
September 2011 - March 2014
University of Vienna
Field of study
  • Media Informatics
September 2007 - June 2011
University of Vienna
Field of study
  • Informatics

Publications

Publications (56)
Article
Full-text available
The ever-increasing network traffic and user expectations at reduced cost make the delivery of high Quality of Experience (QoE) for multimedia services more vital than ever in the eyes of Internet Service Providers (ISPs). Real-time quality monitoring, with a focus on the user, has become essential as the first step in cost-effective provisioning o...
Conference Paper
Full-text available
Assuring user engagement has become a key issue for Internet Service Providers and Over-the-Top Providers. How long are users consuming a service? When are they likely to abandon it due to quality problems? Rather than just estimating perceived audiovisual quality, future quality prediction models will also factor in possible user behavior. This co...
Conference Paper
Full-text available
In this paper, we assess audiovisual quality of HTTP Adaptive Streaming using a novel subjective test design. The goal of this test was to systematically study the impact of both quality variations and stalling events on remembered quality. To gather more ecologically valid results, we wanted to reach a degree of test subject engagement and attenti...
Conference Paper
Full-text available
When users give ratings in subjective Quality of Experience experiments, they may experience a lack of confidence in assigning a score to a stimulus. This results in invalid votes that might need to be removed from the acquired data. We show results from a subjective video quality experiment in which we measured the rating times and asked observers...
Conference Paper
Full-text available
—Spatial Information (SI) and Temporal Information (TI) are frequently-used metrics to classify the spatiotemporal complexity of video content. However, they are mostly used on original video sources, and their impact on actual encoding efficiency is not known. In this paper, we propose a method to determine the compressibility of video sources, th...
Article
Full-text available
The paper presents a series of three new video quality model standards for the assessment of sequences of up to UHD/4K resolution. They were developed in a competition within the International Telecommunication Union (ITU-T), Study Group 12, in collaboration with the Video Quality Experts Group (VQEG), over a period of more than two years. A large...
Conference Paper
Full-text available
With the increasing requirement of users to view high-quality videos with a constrained bandwidth, typically realized using HTTP-based adaptive streaming, it becomes more and more important to determine the quality of the encoded videos accurately, to assess and possibly optimize the overall streaming quality. In this paper, we describe a bitstream...
Conference Paper
Full-text available
As video streaming accounts for the majority of Internet traffic, monitoring its quality is of importance to both Over the Top (OTT) providers as well as Internet Service Providers (ISPs). While OTTs have access to their own analytics data with detailed information, ISPs often have to rely on automated network probes for estimating streaming qualit...
Preprint
Full-text available
This white paper is the outcome of the W\"urzburg seminar on "Crowdsourced Network and QoE Measurements" which took place from 25-26 September 2019 in W\"urzburg, Germany. International experts were invited from industry and academia. They are well known in their communities, having different backgrounds in crowdsourcing, mobile networks, network m...
Poster
Full-text available
Users may experience symptoms of simulator sickness while watching 360°/VR videos with Head-Mounted Displays (HMDs). At present, practically no solution exists that can efficiently eradicate the symptoms of simulator sickness from virtual environments. Therefore, in the absence of a solution, it is required to at least quantify the amount of sickn...
Technical Report
Full-text available
This white paper is the outcome of the Würzburg seminar on "Crowdsourced Network and QoE Measurements" which took place from 25-26 September 2019 in Würzburg, Germany. International experts were invited from industry and academia. They are well known in their communities, having different backgrounds in crowdsourcing, mobile networks, network measu...
Conference Paper
Full-text available
In recent years, with the introduction of powerful HMDs such as Oculus Rift, HTC Vive Pro, the QoE that can be achieved with VR/360° videos has increased substantially. Unfortunately, no standardized guidelines, methodologies and protocols exist for conducting and evaluating the quality of 360° videos in tests with human test subjects. In this pape...
Article
In recent years, with the introduction of powerful HMDs such as Oculus Rift, HTC Vive Pro, the QoE that can be achieved with VR/360° videos has increased substantially. Unfortunately, no standardized guidelines, methodologies and protocols exist for conducting and evaluating the quality of 360° videos in tests with human test subjects. In this pape...
Conference Paper
Full-text available
4K television screens or even with higher resolutions are currently available in the market. Moreover video streaming providers are able to stream videos in 4K resolution and beyond. Therefore, it becomes increasingly important to have a proper understanding of video quality especially in case of 4K videos. To this effect, in this paper, we present...
Conference Paper
Full-text available
The test methods recommended by the International Telecommunication Union (ITU) for assessing 2D video quality are often used for evaluating omnidirectional / 360° videos. In this paper, we compare the performance of three different test methods, Absolute Category Rating (ACR), a modified version of ACR (M–ACR) with double presentation of the test...
Article
Full-text available
The past decades have shown a steady rise in the pixel resolution of digital visualization technologies. New TVs and computer displays available on the consumer market are commonly UHD/4K, and 8K recently started appearing in the commercial world. The added value of such higher resolution is not only indicated by the purported level of visual perfo...
Preprint
It is believed that consistent notation helps the research community in many ways. First and foremost, it provides a consistent interface of communication. Subjective experiments described according to uniform rules are easier to understand and analyze. Additionally, a comparison of various results is less complicated. In this publication we descri...
Conference Paper
Full-text available
Adaptive streaming is fast becoming the most widely used method for video delivery to the end users over the internet. The ITU-T P.1203 standard is the first standardized quality of experience model for audiovisual HTTP-based adaptive streaming. This recommendation has been trained and validated for H.264 and resolutions up to and including full-HD...
Article
Full-text available
Video resolution changes in an HTTP adaptive streaming session may negatively affect the viewer's Quality of Experience. Our goal is, through encoding, to make such resolution changes less noticeable for the viewers. This can be achieved by taking video complexity features into account in the encoding process. In this paper, we compare Constant Bit...
Conference Paper
Full-text available
This paper describes an open dataset and software for ITU-T Rec. P.1203. As the first standardized Quality of Experience model for audiovisual HTTP Adaptive Streaming (HAS), it has been extensively trained and validated on over a thousand audiovisual sequences containing HAS-typical effects (such as stalling, coding artifacts, quality switches). Ou...
Conference Paper
Full-text available
The available Internet bandwidth has a strong impact on the Quality of Experience of video services. In order to manage their network efficiently and prevent customer churn, Internet Service Providers need to constantly monitor the QoE of video services such as YouTube. However, they often only rely on simple measurement scenarios that consider onl...
Conference Paper
Full-text available
In this paper, we compare the Double-Stimulus Impairment Scale (DSIS) and a Modified Absolute Category Rating (M-ACR) subjective quality evaluation method for HEVC/H.265-encoded omnidirectional videos. These two methods differ in the type of rating scale and presentation of stimuli. Results of our test pro- vide insight into the similarities and di...
Conference Paper
Full-text available
In this paper, we perform subjective quality evaluation studies for HEVC/H.265-encoded omnidirectional videos at different bit-rates for two different resolutions (FHD and UHD) on an Oculus Rift. Results of these tests provide insight into appropriate coding and resolution settings for given bitrate constraints, for example in an HTTP-based streami...
Method
Full-text available
This contribution reports on two subjective tests to evaluate the subjective quality of 360° omnidirectional videos in Head Mounted Displays (HMDs). For the tests, adapted versions of the conventional Absolute Category Rating (ACR) method were applied, aiming to provide reliable subjective ratings for short (Test 2) as well as long video sequences...
Conference Paper
Full-text available
HTTP adaptive streaming (HAS) has become the de-facto standard for video streaming to ensure continuous multime-dia service delivery under irregularly changing network conditions. Many studies already investigated the detrimental impact of various playback characteristics on the Quality of Experience of end users, such as initial loading, stalling...
Conference Paper
Full-text available
When users decide to cancel a video playback because the video is not loading, this is a first step in their abandonment of a service. Internet or video service providers however are strongly interested in engaging people to continue using their offers. In this work, we are investigating when, how, and why users are reacting to typical problems pre...
Conference Paper
Full-text available
User behavior is one of the key components of customer engagement and abandonment, which result from a good or bad Quality of Experience. However, methods to evoke and measure user behavior are still understudied. This paper presents an in-depth look at a study in which we measured user behavior during video streaming consumption in a controlled la...
Conference Paper
Full-text available
This paper presents a conceptual model that relates the quality formation process—as established in literature—to human behavior in multimedia consumption. It gives theoretical definitions of behavioral aspects to allow a common understanding of the terms in the User Experience and Quality of Experience communities. The work creates a basis for the...
Conference Paper
Full-text available
This paper proposes a highly flexible framework to stream videos using unreliable transport mechanisms involving combinations of MPEG-2 TS, RTP and UDP. The framework currently supports the H.264 and H.265 codecs. Transmission impairments such as packet loss, delay and jitter can also be simulated during streaming or offline. Various adjustable mod...
Article
In January 2014, the new ITU-T P.913 recommendation for measuring subjective video, audio and multimedia quality in any environment has been published. This document does not contain any time-continuous subjective method. However, environmental parameter values are changing continuously in a majority of outdoor and also most indoor environments. To...
Conference Paper
Full-text available
Tags assigned by users to shared content can be ambiguous. As a possible solution, we propose semantic tagging as a collaborative process in which a user selects and associates Web resources drawn from a knowledge context. We applied this general technique in the specific context of online historical maps and allowed users to annotate and tag them....
Conference Paper
Full-text available
This paper considers the problem of decreasing the number of video sequences to present in a subjective experiment so that the duration stays under the standard recommendations , while allowing to evaluate the perceived quality on a large set of configurations and contents. We present the constraints and related issues, then compare three selection...
Conference Paper
Full-text available
As smartphones and other mobile multimedia devices are becoming part of our everyday life, supported by the continuous development of mobile broadband services all around the world, mobile TV is naturally becoming a more and more popular application. Mainly because of the high cost of content production and delivery, most of current mo-bile TV serv...
Conference Paper
Full-text available
As more and more mobile mobile stereoscopic displays be-come available in phones and portable game consoles, many factors still have to be considered for the successful imple-mentation of an end-to-end mobile 3D television system. Limited bandwidth in 3G networks require a tradeoff be-tween perceived quality and bit rate shaping. When impor-tant ob...
Conference Paper
Full-text available
Historic maps are valuable scholarly resources that record information often retained by no other written source. With the YUMA Map Annotation Tool we want to facilitate collaborative annotation for scholars studying historic maps, and allow for semantic augmentation of annotations with structured, contextually relevant information retrieved from L...
Chapter
14.1 Introduction Mobile TV on mobile phones is an important example for convergence of telecommunications and broadcasting services and of telephones and television devices; the mobile phone is becoming a multimedia mobile integration medium. Television on the mobile phone is also referred to as television on the “third screen” [13].
Conference Paper
Full-text available
User interaction has always been one of the most crucial points when evaluating the quality of experience of a service. Mobile television, especially when received over DVB-H or in other small bandwidth transmission environments such as UMTS networks, imposes some restrictions to this interaction, since switching from one channel to another require...
Conference Paper
Quality of Experience in mobile multimedia services is subject to environmental changes. Especially in urban environments, several types of background noises affect the perceived quality of audio content, and the characteristics of noise can rapidly change within a few minutes of travel. Also, the change of loudness in the multimedia content itself...
Conference Paper
Mobile TV is already available for several years. The provided quality is generally attractive but of course, data transfer is not always optimal. It can be subject to disturbances such as fading, noise or interference that are responsible for temporary quality decreases. In Europe, the common way of realising mobile broadcasting is the implementat...
Conference Paper
Full-text available
Some time ago it has been understood that subjective qual-ity assessment is crucial to determine the multimedia quality of distorted or compressed data. Generally, researchers fol-low the ITU recommendations to carry out their user tests. There, it is specified that at least fifteen non-experts need to act as test-persons. It seems that in many opp...
Conference Paper
Mobile devices are small and environmental conditions are far from being optimal. Hence, only few details can be perceived by the mobile user. The main aim of this demonstration consists in optimizing standard television content in respect to mobile TV constraints.

Projects

Projects (3)
Project
The aim of this project to find and study the factors such as Simulator Sickness, Presence, and Immersion on QoE.