COBIRAS: Offering a Continuous Bit Rate Slide to Maximize DASH Streaming Bandwidth Utilization
ACM Transactions on Multimedia Computing Communications and Applications (ACM TOMM)
[PDF]
Michael Seufert (University of Augsburg, Germany), Marius Spangenberger (University of Würzburg, Germany), Fabian Poignée (University of Würzburg, Germany), Florian Wamser (Lucerne University of Applied Sciences and Arts, Switzerland), Werner Robitza (AVEQ GmbH, Austria), Christian Timmerer (Christian Doppler-Labor ATHENA, Alpen-Adria-Universität, Austria), Tobias Hoßfeld (University of Würzburg, Germany)
Comparison of classical DASH system to proposed DASH system with COBIRAS, JITE at the DASH server, and MinOff at the DASH client.}
Abstract: Reaching close-to-optimal bandwidth utilization in Dynamic Adaptive Streaming over HTTP (DASH) systems can, in theory, be achieved with a small discrete set of bit rate representations. This includes typical bit rate ladders used in state-of-the-art DASH systems. In practice, however, we demonstrate that bandwidth utilization, and consequently the Quality of Experience (QoE), can be improved by offering a continuous set of bit rate representations, i.e., a continuous bit rate slide (COBIRAS). Moreover, we find that the buffer fill behavior of different standard adaptive bit rate (ABR) algorithms is sub-optimal in terms of bandwidth utilization. To overcome this issue, we leverage COBIRAS’ flexibility to request segments with any arbitrary bit rate and propose a novel ABR algorithm MinOff, which helps maximizing bandwidth utilization by minimizing download off-phases during streaming. To avoid extensive storage requirements with COBIRAS and to demonstrate the feasibility of our approach, we design and implement a proof-of-concept DASH system for video streaming that relies on just-in-time encoding (JITE), which reduces storage consumption on the DASH server. Finally, we conduct a performance evaluation on our testbed and compare a state-of-the-art DASH system with few bit rate representations and our JITE DASH system, which can offer a continuous bit rate slide, in terms of bandwidth utilization and video QoE for different ABR algorithms.
Additional Key Words and Phrases: Dynamic Adaptive Streaming over HTTP, DASH, HTTP Adaptive Streaming, HAS, Encoding, Bit Rate Representations, Adaptive Bit Rate, ABR, Bandwidth Utilization, Quality of Experience, QoE
Biography: Christian Timmerer is a full professor of computer science at Alpen-Adria-Universität Klagenfurt (AAU), Institute of Information Technology (ITEC) and he is the director of the Christian Doppler (CD) Laboratory ATHENA (
Samira Afzal is a postdoctoral researcher at Alpen-Adria-Universität Klagenfurt, Austria, and in collaborating with Bitmovin. Before, she was a postdoctoral researcher at the University of Sao Paulo, researching deeply on IoT, SWARM, and Surveillance Systems. She graduated with her Ph.D. in November 2019 from the University of Campinas (UNICAMP). During her Ph.D., she collaborated with Samsung on a project in the area of mobile video streaming over heterogeneous wireless networks and multipath transmission methods in order to increase perceived
