OPTIMAL MULTI-CODEC ADAPTIVE BITRATE STREAMING

We consider adaptive bitrate streaming system serving a population of mobile devices, where first subset of devices can only decode first codec (e.g. H.264), another subset of devices can only decode the second codec (e.g. HEVC), and where the third sub-set of devices can decode both codecs and can also seamlessly switch between them. We focus on a problem of design of encoding profiles, defining pluralities of streams encoded by both codecs, such that overall quality delivered by such system is optimal. We define this problem mathematically, show how it maps to known classes of optimization problems, and identify approach for solving it numerically. Examples of optimal ladders constructed for different models of networks as well as types of content are provided. It is shown that proposed approach leads to significant improvements compared to systems employing ABR ladders constructed separately for each codec.