Vignesh V Menon

Paper accepted – Content-adaptive Encoder Preset Prediction for Adaptive Live Streaming

2022 Picture Coding Symposium (PCS)

December 7-9, 2022 | San Jose, CA, USA

Conference Website

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


In live streaming applications, a fixed set of bitrate-resolution pairs (known as bitrate ladder) is generally used to avoid additional pre-processing run-time to analyze the complexity of every video content and determine the optimized bitrate ladder. Furthermore, live encoders use the fastest available preset for encoding to ensure the minimum possible latency in streaming. For live encoders, it is expected that the encoding speed is equal to the video framerate. However, an optimized encoding preset may result in (i) increased Quality of Experience (QoE) and (ii) improved CPU utilization while encoding. In this light, this paper introduces a Content-Adaptive encoder Preset prediction Scheme (CAPS) for adaptive live video streaming applications. In this scheme, the encoder preset is determined using Discrete Cosine Transform (DCT)-energy-based low-complexity spatial and temporal features for every video segment, the number of
CPU threads allocated for each encoding instance, and the target encoding speed. Experimental results show that CAPS yields an overall quality improvement of 0.83 dB PSNR and 3.81 VMAF with the same bitrate, compared to the fastest preset encoding
of the HTTP Live Streaming (HLS) bitrate ladder using x265 HEVC open-source encoder. This is achieved by maintaining the desired encoding speed and reducing CPU idle time.


Paper accepted – Light-weight Video Encoding Complexity Prediction using Spatio Temporal Features

2022 IEEE 24th International Workshop on Multimedia Signal Processing (MMSP)

September 26-28, 2022 | Shanghai, China

Conference Website

Hadi Amirpour (Alpen-Adria-Universität Klagenfurt), Prajit T Rajendran (Universite Paris-Saclay, Paris, France), Vignesh V Menon (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)


The increasing demand for high-quality and low-cost video streaming services calls for the prediction of video encoding complexity. The prior prediction of video encoding complexity including encoding time and bitrate predictions are used to allocate resources and set optimized parameters for video encoding effectively. In this paper, a light-weight video encoding complexity prediction (VECP) scheme that predicts the encoding bitrate and the encoding time of video with high accuracy is proposed. Firstly, low-complexity Discrete Cosine Transform (DCT)-energy-based features, namely spatial complexity, temporal complexity, and brightness of videos are extracted, which can efficiently
represent the encoding complexity of videos. The latent vectors are also extracted from a Convolutional Neural Network (CNN) with MobileNet as the backend to obtain additional features from representative frames of each video to assist the prediction process. The extreme gradient boosting (XGBoost) regression algorithm is deployed to predict video encoding complexity using the extracted features. The experimental results demonstrate that VECP predicts the encoding bitrate with an error percentage of up to 3.47% and encoding time with an error percentage of up to 2.89%, but with a significantly low overall latency of 3.5 milliseconds per frame which makes it suitable for both Video on Demand (VoD) and live streaming applications.

VECP architecture

Vignesh V Menon

Paper accepted – ETPS: Efficient Two-pass Encoding Scheme for Adaptive Live Streaming

2022 IEEE International Conference on Image Processing (ICIP)

October 16-19, 2022 | Bordeaux, France

Conference 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 two-pass encoding, also known as multi-pass encoding, the input video content is analyzed in the first-pass to help the second-pass encoding utilize better encoding decisions and improve overall compression efficiency. In live streaming applications, a single-pass encoding scheme is mainly used to avoid the additional first-pass encoding run-time to analyze the complexity of every video content. This paper introduces an Efficient low-latency Two-Pass encoding Scheme (ETPS) for live video streaming applications. In this scheme, Discrete Cosine Transform (DCT)-energy-based low-complexity spatial and temporal features for every video segment are extracted in the first-pass to predict each target bitrate’s optimal constant rate factor (CRF) for the second-pass constrained variable bitrate (cVBR) encoding. Experimental results show that, on average, ETPS compared to a traditional two-pass average bitrate encoding scheme yields encoding time savings of 43.78% without any noticeable drop in compression efficiency. Additionally, compared to a single-pass constant bitrate (CBR) encoding, it yields bitrate savings of 10.89% and 8.60% to maintain the same PSNR and VMAF, respectively.

ETPS architecture

Paper accepted: MOGPlay: A Decentralized Crowd Journalism Application for Democratic News Production @ 2022 IEEE/ACM International Conference

Title: MOGPlay: A Decentralized Crowd Journalism Application for Democratic News Production

Authors: Ines Rito Lima, Claudia Marinho,Vasco Filipe, Alexandre Ulisses, Nishant Saurabh, Antorweep Chakravorty, Zhiming Zhao, Atanas Hristov, Radu Prodan

2022 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM)

Abstract: Media production and consumption behaviors are changing in response to  new technologies and demands, giving birth to a new generation of social  applications. Among them, crowd journalism represents a novel way of constructing democratic and trustworthy news relying on ordinary citizens arriving at breaking news locations and capturing relevant videos using their smartphones. The ARTICONF project proposes a trustworthy, resilient, and globally sustainable toolset for developing decentralized applications (DApps). Leveraging the ARTICONF tools, we introduce a new DApp for crowd journalism called MOGPlay. MOGPlay collects and manages audio-visual content generated by citizens and provides a secure blockchain platform that rewards all stakeholders involved in professional news production. Besides live streaming, MOGPlay offers a marketplace for audio-visual content trading among citizens and free journalists with an internal token ecosystem. We discuss the functionality and implementation of the MOGPlay DApp and illustrate three pilot crowd journalism live scenarios that validate the prototype.


Hermann Hellwagner received appreciation award

We are happy to announce and our congratulations to Dr. Hermann Hellwagner for receiving the appreciation award of Carinthia in the area of natural/technical sciences.


Paper accepted: Towards Better Quality of Experience in HTTP Adaptive Streaming

16th International Conference on Signal Image Technology & Internet based Systems – Dijon, France – October 19-21, 2022

Conference Website

Babak Taraghi (Alpen-Adria-Universität Klagenfurt, Austria), Selina Zoë Haack (Alpen-Adria-Universität Klagenfurt, Austria), and Christian Timmerer (Alpen-Adria-Universität Klagenfurt, Austria)

Abstract: HTTP Adaptive Streaming (HAS) is nowadays a popular solution for multimedia delivery. The novelty of HAS lies in the possibility of continuously adapting the streaming session to current network conditions, facilitated by Adaptive Bitrate (ABR) algorithms. Various popular streaming and Video on Demand services such as Netflix, Amazon Prime Video, and Twitch use this method. Given this broad consumer base, ABR algorithms continuously improve to increase user satisfaction. The insights for these improvements are, among others, gathered within the research area of Quality of Experience (QoE). Within this field, various researchers have dedicated their works to identifying potential impairments and testing their impact on viewers’ QoE. Two frequently discussed visual impairments influencing QoE are stalling events and quality switches. So far, it is commonly assumed that those stalling events have the worst impact on QoE. This paper challenged this belief and reviewed this assumption by comparing stalling events with multiple quality and high amplitude quality switches. Two subjective studies were conducted. During the first subjective study, participants received a monetary incentive, while the second subjective study was carried out with volunteers. The statistical analysis demonstrated that stalling events do not result in the worst degradation of QoE. These findings suggest that a reevaluation of the effect of stalling events in QoE research is needed. Therefore, these findings may be used for further research and to improve current adaptation strategies in ABR algorithms.


Paper accepted: ARARAT: A Collaborative Edge-Assisted Framework for HTTP Adaptive Video Streaming

IEEE Transactions on Network and Service Management (TNSM)

Journal Website

Authors: Reza Farahani (Alpen-Adria-Universität Klagenfurt, Austria), Mohammad Shojafar (University of Surry, UK), Christian Timmerer (Alpen-Adria-Universität Klagenfurt, Austria), Farzad Tashtarian (Alpen-Adria-Universität Klagenfurt, Austria), Mohammad Ghanbari (University of Essex, UK), and Hermann Hellwagner (Alpen-Adria-Universität Klagenfurt, Austria)

Abstract: With the ever-increasing demands for high-definition and low-latency video streaming applications, network-assisted video streaming schemes have become a promising complementary solution in the HTTP Adaptive Streaming (HAS) context to improve users’ Quality of Experience (QoE) as well as network utilization. Edge computing is considered one of the leading networking paradigms for designing such systems by providing video processing and caching close to the end-users. Despite the wide usage of this technology, designing network-assisted HAS architectures that support low-latency and high-quality video streaming, including edge collaboration is still a challenge. To address these issues, this article leverages the Software-Defined Networking (SDN), Network Function Virtualization (NFV), and edge computing paradigms to propose A collaboRative edge-Assisted framewoRk for HTTP Adaptive video sTreaming (ARARAT). Aiming at minimizing HAS clients’ serving time and network cost, besides considering available resources and all possible serving actions, we design a multi-layer architecture and formulate the problem as a centralized optimization model executed by the SDN controller. However, to cope with the high time complexity of the centralized model, we introduce three heuristic approaches that produce near-optimal solutions through efficient collaboration between the SDN controller and edge servers. Finally, we implement the ARARAT framework, conduct our experiments on a large-scale cloud-based testbed including 250 HAS players, and compare its effectiveness with state-of-the-art systems within comprehensive scenarios. The experimental results illustrate that the proposed ARARAT methods (i) improve users’ QoE by at least 47%, (ii) decrease the streaming cost, including bandwidth and computational costs, by at least 47%, and (iii) enhance network utilization, by at least 48% compared to state-of-the-art approaches.


Hadi Amirpour to give a talk at INSA France

LiVE: Toward Better Live Video Experience

INSA, France

 27th September 2022 | Rennes, France


Abstract: In this presentation, we first introduce the principles of video streaming and the existing challenges. While live video streaming is expected to continue growing at an accelerated pace, one potential area for optimization that has remained relatively untapped is the use of content-aware encoding to improve the quality of live contribution streams due to avoid of latency. In this talk, we introduce revolutionary real-time content-aware video quality improvement methods for live applications that keep the added latency very low.




Hadi Amirpour is a postdoctoral researcher at the University of Klagenfurt. He received his B.Sc. degrees in Electrical and Biomedical Engineering, and he pursued his M.Sc. in Electrical Engineering. He got his Ph.D. in computer science from the University of Klagenfurt in 2022. He was involved in the project EmergIMG, a Portuguese consortium on emerging imaging technologies, funded by the Portuguese funding agency and H2020. Currently, he is working on the ATHENA project in cooperation with its industry partner Bitmovin. His research interests are image processing and compression, video processing and compression, quality of assessment, emerging 3D imaging technology, and medical image analysis.

Bringing the Carinthian gaming scene to the next level

The “Game Studies and Engineering” master’s program can be studied at the University of Klagenfurt for five years. It’s much more about technical skills, a critical understanding of the influence of games on society “as well as the courage and creativity to use this knowledge and experience in your own innovative ways for yourself and for society,” says program director Felix Schniz.
Carinthian newspaper “Kleine Zeitung” interviewed current and former ITEC team members about how games will change in the future. Read the whole article here about former “Octopus project” colleagues Fabian and Daniela from “Dirty Paws Studio” and Sebastian’s “A Webbing Journey” (German only).



Paper accepted: CardioHPC: Serverless Approaches for Real-Time Heart Monitoring of Thousands of Patients @17th Workshop on Workflows in Support of Large-Scale Science

Titel: CardioHPC: Serverless Approaches for Real-Time Heart Monitoring of Thousands of Patients

Authors: Marjan Gusev, Sashko Ristov, Andrei Amza, Armin Hohenegger, Radu Prodan, Dimitar Mileski, Pano Gushev, Goran Temelkov

17th Workshop on Workflows in Support of Large-Scale Science

Abstract: We analyze a heart monitoring center for patients wearing electrocardiogram sensors outside hospitals. This prevents serious heart damages and increases life expectancy and health-care efficiency. In this paper, we address a problem to provide a scalable infrastructure for the real-time processing scenario for at least 10000 patients simultaneously, and efficient fast processing architecture for the postponed scenario when patients upload data after realized measurements. CardioHPC is a project to realize a simulation of these two scenarios using digital signal processing algorithms and artificial intelligence-based detection and classification software for automated reporting and alerting. We elaborate the challenges we met in experimenting with different serverless implementations: 1) container-based on Google Cloud Run, and 2) Function-as-a-Service (FaaS) on AWS Lambda. Experimental results present the effect of overhead in the request and transfer time, and speedup achieved by analyzing the response time and throughput on both container-based and FaaS implementations as serverless workflows.