On 20 October 2022 Felix gave the talk “Walk Like an Englishman? The Cultural Experience of Walking Simulators” as part of the Transformative Play Initiative 2022 conference at Uppsala University, Sweden.
The content of the presentation was accepted for an article in the International Journal of Role-Playing (IJRP).
Felix talk titled “A Walk in the Park? Designing a Very British Gaming Experience” which he will be given together with Christoph Kaindel has been accepted for the Future and Reality of Gaming (FROG) Conference 2022 at Danube University Krems.

OTEC: An Optimized Transcoding Task Scheduler for Cloud and Fog Environments

ACM CoNEXT 2022ViSNext

Samira Afzal (Alpen-Adria-Universität Klagenfurt), Farzad Tashtarian (Alpen-Adria-Universität Klagenfurt), Hamid Hadian (Alpen-Adria-Universität Klagenfurt), Alireza Erfanian (Alpen-Adria-Universität Klagenfurt), Christian Timmerer (Alpen-Adria-Universität Klagenfurt), and Radu Prodan (Alpen-Adria-Universität Klagenfurt)


Encoding and transcoding videos into multiple codecs and representations is a significant challenge that requires seconds or even days on high-performance computers depending on many technical characteristics, such as video complexity or encoding parameters. Cloud computing offering on-demand computing resources optimized to meet the needs of customers and their budgets is a promising technology for accelerating dynamic transcoding workloads. In this work, we propose OTEC, a novel multi-objective optimization method based on the mixed-integer linear programming model to optimize the computing instance selection for transcoding processes. OTEC determines the type and number of cloud and fog resource instances for video encoding and transcoding tasks with optimized computation cost and time. We evaluated OTEC on AWS EC2 and Exoscale instances for various administrator priorities, the number of encoded video segments, and segment transcoding times. The results show that OTEC can achieve appropriate resource selections and satisfy the administrator’s priorities in terms of time and cost minimization.

OTEC architecture overview.

As a Hipeac member, we are hosting Zeinab Bakhshi, a Ph.D. student from Mälardalens University in Sweden. Zeinab achieved a Hipeac collaboration grant and is now hosted by Profesor Radu Prodan to expand her research on container-based fog architectures. Taking advantage of the multi-layer continuum computing architecture in Klagenfurt lab helps Zeinab deploy the use case she is researching on. These scientific experiments take her research work to the next level. We are planning to publish our collaborative research work in a series of papers based on the upcoming results.

Vignesh V Menon

Transactions on Multimedia Computing Communications and Applications (TOMM)

Journal Website

Vignesh V Menon (Alpen-Adria-Universität Klagenfurt),  Hadi Amirpour (Alpen-Adria-Universität Klagenfurt), Mohammad Ghanbari (School of Computer Science and Electronic Engineering, University of Essex, Colchester, UK)and Christian Timmerer (Alpen-Adria-Universität Klagenfurt)


In HTTP Adaptive Streaming (HAS), videos are encoded at multiple bitrates and spatial resolutions (i.e., representations) to adapt to the heterogeneity of network conditions, device attributes, and end-user preferences. Encoding the same video segment at
multiple representations increases costs for content providers. State-of-the-art multi-encoding schemes improve the encoding process by utilizing encoder analysis information from already encoded representation(s) to reduce the encoding time of the remaining
representations. These schemes typically use the highest bitrate representation as the reference to accelerate the encoding of the remaining representations. Nowadays, most streaming services utilize cloud-based encoding techniques, enabling a fully parallel
encoding process to reduce the overall encoding time. The highest bitrate representation has the highest encoding time than the other representations. Thus, utilizing it as the reference encoding is unfavorable in a parallel encoding setup as the overall encoding time is bound by its encoding time. This paper provides a comprehensive study of various multi-rate and multi-encoding schemes in both serial and parallel encoding scenarios. Furthermore, it introduces novel heuristics to limit the Rate Distortion Optimization (RDO) process across various representations. Based on these heuristics, three multi-encoding schemes are proposed, which rely on encoder analysis sharing across different representations: (i) optimized for the highest compression efficiency, (ii) optimized for the best compression efficiency-encoding time savings trade-off, and (iii) optimized for the best encoding time savings. Experimental results demonstrate that the proposed multi-encoding schemes (i), (ii), and (iii) reduce the overall serial encoding time by 34.71%, 45.27%, and 68.76% with a 2.3%, 3.1%, and 4.5% bitrate increase to maintain the same VMAF, respectively compared to stand-alone encodings. The overall parallel encoding time is reduced by 22.03%, 20.72%, and 76.82% compared to stand-alone encodings for schemes (i), (ii), and (iii), respectively.

An example of video representations’ storage in HAS. The input video is encoded at multiple resolutions and bitrates. Novel multi-rate and multi-resolution encoder
analysis sharing methods are presented to accelerate encoding in more than one representation.

2022 IEEE International Conference on Image Processing (ICIP)

October 16-19, 2022 | Bordeaux, France

Conference Website


Abstract: According to the Bitmovin Video Developer Report 2021, live streaming at scale has the highest scope for innovation in video streaming services. Currently, there are no open-source implementations available which can predict video complexity for live streaming applications. To this light, we plan to demo the functions of VCA software, and show accuracy of the complexities analyzed by VCA (https://vca.itec.aau.at) using the heatmaps, and show-case the speed of video complexity analysis. VCA can achieve an analysis speed of about 370fps compared to the 5fps speed of the reference SITI implementation. Hence, we show that it can be used for live streaming applications.

In the demo, we also showcase an application of VCA in detail: optimized CRF prediction for adaptive streaming, which is being presented in ICIP’22 (Paper ID: 2030). This scheme improves the compression efficiency of the conventional ABR encoding for live streaming.


  • Vignesh V Menon, University of Klagenfurt, Austria (vignesh.menon@aau.at)
  • Christian Feldmann, Bitmovin, Austria (christian.feldmann@bitmovin.com)
  • Hadi Amirpour, University of Klagenfurt, Austria (hadi.amirpour@aau.at)
  • Christian Timmerer, Bitmovin, Austria (christian.timmerer@bitmovin.com)

IEEE Access, A Multidisciplinary, Open-access Journal of the IEEE


Minh Nguyen (Christian Doppler Laboratory ATHENA, Alpen-Adria-Universität Klagenfurt), Daniele Lorenzi (Christian Doppler Laboratory ATHENA, Alpen-Adria-Universität Klagenfurt), Farzad Tashtarian (Christian Doppler Laboratory ATHENA, Alpen-Adria-Universität Klagenfurt), Hermann Hellwagner (Christian Doppler Laboratory ATHENA, Alpen-Adria-Universität Klagenfurt), Christian Timmerer (Christian Doppler Laboratory ATHENA, Alpen-Adria-Universität Klagenfurt)

(*) Minh Nguyen and Daniele Lorenzi contributed equally to this work


Abstract: HTTP Adaptive Streaming (HAS) solutions use various adaptive bitrate (ABR) algorithms to select suitable video qualities with the objective of coping with the variations of network connections. HTTP has been evolving with various versions and provides more and more features. Most of the existing ABR algorithms do not significantly benefit from the HTTP development when they are merely supported by the most recent HTTP version. An open research question is “How can new features of the recent HTTP versions be used to enhance the performance of HAS?” To address this question, in this paper, we introduce Days of Future Past+ (DoFP+ for short), a heuristic algorithm that takes advantage of the features of the latest HTTP version, HTTP/3, to provide high Quality of Experience (QoE) to the viewers. DoFP+ leverages HTTP/3 features, including (i) stream multiplexing, (ii) stream priority, and (iii) request cancellation to upgrade low-quality segments in the player buffer while downloading the next segment. The qualities of those segments are selected based on an objective function and throughput constraints. The objective function takes into account two factors, namely the (i) average bitrate and the (ii) video instability of the considered set of segments. We also examine different strategies of download order for those segments to optimize the QoE in limited resources scenarios. The experimental results show an improvement in QoE by up to 33% while the number of stalls and stall duration for DoFP+ are reduced by 86% and 92%, respectively, compared to state-of-the-art ABR schemes. In addition, DoFP+ saves on average up to 16% downloaded data across all test videos. Also, we find that downloading segments sequentially brings more benefits for retransmissions than concurrent downloads; and lower-quality segments should be upgraded before other segments to gain more QoE improvement. Our source code has been published for reproducibility at https://github.com/cd-athena/DoFP-Plus.

Keywords: HTTP/3, ABR algorithm, QoE, HAS, DASH

DataCloud will research and develop novel methods to support the complete lifecycle of #BigData pipelines processing.Follow us to know more about #datacloud2020

On the first two days of October 2022, Sebastian Uitz and Michael Steinkellner presented their game “A Webbing Journey” at the Vienna Comic Con 2022 (VIECC 2022). The new demo level from Gamescom was incorporated into the existing demo and replaced the old first level. In addition, the art style was updated, and the new arachnophobia mode was added to help everyone enjoy our game, even those afraid of spiders. This event was the biggest Austrian event we attended yet, with over 35.000 visitors. Next to meeting some cool Austrian game devs and having many happy players, we also had an interview with the FM4 Spielekammerl about our game.

From Wednesday, 24.08.2022, until Sunday, 28.08.2022, players from all over the world played our game “A Webbing Journey” at Gamescom 2022 in Cologne. Our booth was run by Sebastian Uitz, Manuel Santner, and Fabian Schober, and we have been one of the only two Austrian games in the indie area this year. The second one is Gibbon from Broken Rules. The size of the Gamescom is just crazy compared to the Austrian events, with over 250.000 people attending this year. We prepared a new demo level for this event, and the feedback was great, as always. In addition, we made valuable connections to the games industry through other game devs, publishers, and the press.

The futurezone Awards 2022 are looking for the most innovative ideas and projects. Three finalists (each category) have now been selected from the numerous submissions.

ITEC was nominated for two projects: 5G Virtual Realities and GAIA (together with Bitmovin).