Look Ahead: a DASH adaptation algorithm

Abstract

This paper proposes a video quality adaptation algorithm based on the Dynamic Adaptive Streaming over HTTP (DASH) standard for on-demand video services. When a video is encoded with constant quality, the resulting bitstream has variable bitrate due to the inherent nature of the video encoding process. The proposed algorithm, called Look Ahead, takes into account this bitrate variability in order to calculate, on the fly, the appropriate quality level that minimizes the number of interruptions during the playback. Moreover, the Look Ahead algorithm has been implemented and integrated into ExoPlayer v2, the latest version of the library developed by Google to play DASH contents. The proposed algorithm is compared to the Müller and Segment Aware Rate Adaptation (SARA) algorithms as well as to the adaptive algorithm integrated into ExoPlayer. The comparison reflects that Look Ahead outperforms the Müller, SARA and the ExoPlayer adaptive algorithms in terms of number and duration of video playback stalls, with hardly decreasing the average video quality.