On multiple media representations and CDN performance

Abstract

This paper proposes a mathematical model describing the effects of using multiple media representations on CDN performance in HTTP-based streaming systems. Specifically, we look at cases of using multiple versions of the same content packaged differently and derive an asymptotic formula for CDN cache-miss probability considering parameters of the content's distribution and the distribution of formats used for packaging and delivery. We then study the validity of this proposed formula by considering statistics collected for several streaming deployments using mixed HLS and DASH packaging and show that it predicts the experimentally observed data reasonably well. We further discuss several possible extensions and applications of this proposed model.