In ABR (adaptive bit rate) streaming, the player controls the quality (bit rate) selection function of its maximum available bandwidth estimation and based on the buffer level. The player has one objective: to maximize the quality of experience (QoE) perceived by the user while avoiding rebuffering. Bandwidth estimation performed by the player is usually based on HTTP (application layer), which does not work properly in some situations like with CMAF low latency. With the latter, a video segment is split into chunks that are coded and transmitted continuously in such a way that a segment is sent and received roughly at the video bit rate. Relying on the buffer level is not really feasible as with low latency the aim is to have the buffer as small as possible. In order to mitigate this problem, several player-side algorithms have been proposed and tested through a common test framework.

We have adapted the test environment in order to test a server-side approach wherein the server decides about the video segment’s bitrate/quality relying on bandwidth estimation relying on the underlaying transport layer’s congestion control (e.g. BBR). Several test campaigns have shown the merits of the server-side approach beating the best client-side algorithms. In my presentation, I introduce the basics of the server side ABR approach (in particular how it fits with standard client-side approach such as MPEG DASH), I give details of the test bed and present the measurement results comparing with the best-known client-side algorithms. This talk was presented at Demuxed ’22, a conference for video nerds in San Francisco featuring amazing talks like this one. Demuxed ’22 was made possible by sponsors like our Platinum sponsor Daily (https://daily.co) and organized by people from Mux (https://mux.com). For more information about the conference and community, see https://2022.demuxed.com.