The threat of climate change requires a drastic reduction of global greenhouse gas (GHG) emissions in several societal spheres. Thus, this also applies to reducing and rethinking the energy consumption of digital technologies. Video streaming technology is responsible for more than half of digital technology’s global impact [ref]. There is rapid growth, also now with digital and remote work has become more mainstream, in the amount of video data volume, processing of video content, and streaming which affects the rise of energy consumption and its associated GHG emissions.

The International Workshop on Green Multimedia Systems 2023 (GMSys 2023) aims to bring together experts and researchers to present and discuss recent developments and challenges for energy reduction in multimedia systems. This workshop focuses on innovations, concepts, and energy-efficient solutions from video generation to processing, delivery, and further usage.

Find further info at


A pre-kickoff meeting for Graph-Massivizer took place on November 4, 2022, at Vrije Universiteit Amsterdam. Ana Lucia Varbanescu, Michael Cochez, Alexandru Iosup, and Radu Prodan discussed the scientific goals of the Graph Massivizer project and how to exceed them.

A new online article about Graphmassivizer has been published in the Science blog; check it out HERE.

29th International Conference on MultiMedia Modeling
9 – 12 January 2023 | Bergen, Norway

Daniele Lorenzi (Alpen-Adria-Universität Klagenfurt), Farzad Tashtarian (Alpen-Adria-Universität Klagenfurt), Hadi Amirpour (Alpen-Adria-Universität Klagenfurt), Christian Timmerer (Alpen-Adria-Universität Klagenfurt), and Hermann Hellwagner (Alpen-Adria-Universität Klagenfurt)


HTTP Adaptive Streaming (HAS) is the predominant technique to deliver video contents across the Internet with the increasing demand of its applications. With the evolution of videos to deliver more immersive experiences, such as their evolution in resolution and framerate, highly efficient video compression schemes are required to ease the burden on the delivery process. While AVC/H.264 still represents the most adopted codec, we are experiencing an increase in the usage of new generation codecs (HEVC/H.265, VP9, AV1, VVC/H.266, etc.). Compared to AVC/H.264, these codecs can either achieve the same quality besides a bitrate reduction or improve the quality while targeting the same bitrate. In this paper, we propose a Mixed-Binary Linear Programming (MBLP) model called Multi-Codec Optimization Model at the edge for Live streaming (MCOM-Live) to jointly optimize (i) the overall streaming costs, and (ii) the visual quality of the content played
out by the end-users by efficiently enabling multi-codec content delivery. Given a video content encoded with multiple codecs according to a fixed bitrate ladder, the model will choose among three available policies, i.e., fetch, transcode, or skip, the best option to handle the representations. We compare the proposed model with traditional approaches used in the industry. The experimental results show that our proposed method can reduce the additional latency by up to 23% and the streaming costs by up to 78%, besides improving the visual quality of the delivered segments by up to 0.5 dB, in terms of PSNR.

MCOM architecture overview.

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.

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

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).