Server-Side Versus Client-Side Synchronization for Watch Together Applications Using CMAF Low Latency

Abstract

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Watch together is an application that was widely deployed during the COVID-19 global health crisis. Early results show a much longer viewing time when the feature is activated. The synchronization between the A/V streamed content, combined with the need to have a low, end-to-end latency compatible with the user interactions through integrated social media apps, is challenging, especially when watch together is deployed on all devices. The legacy approach used by existing watch together applications is to rely on a master user that will drive the other members of the group using an overlay control protocol to make sure that all the players will synchronize their playback. This article proposes a scheme that uses the built-in synchronization provided in Common Media Application Format (CMAF) low latency for both Dynamic Adaptive Streaming over HTTP (DASH) and HTTP Live Streaming (HLS), enabling a subsecond time delay between clients in the same geographical location</i> .