Abstract
When a video is encoded with constant quality, the resulting bitstream will have variable bitrate due to the inherent nature of the encoding process. This paper proposes an Adaptive Bitrate Streaming (ABR) algorithm, called Look Ahead, which takes into account this variability in order to calculate, in real time, the appropriate quality level that minimizes the number of interruptions during playback. The algorithm is based on Dynamic Adaptive Streaming over HTTP (DASH) standard for on-demand services. It has been implemented and integrated into ExoPlayer v2, the latest library developed by Google to play DASH contents. The proposed algorithm is compared with Müller and Segment Aware Rate Adaptation (SARA) algorithms as well as the default ABR algorithm of ExoPlayer, using the most relevant QoE parameters: number of stalls, average quality, and representation switches. This paper also proposes two new QoE models for evaluating ABR algorithms, one based on VMAF (Video Multimethod Assessment Fusion) developed by Netflix. Results show that Look Ahead outperforms the compared algorithms in terms of stalls while hardly decreasing video quality, and that the proposed models are more accurate than similar existing ones.
Type
Publication
Multimedia Tools and Applications, 79(33–34), 25143–25170. Springer