Optimal rendition resolution selection algorithm for web streaming players

Abstract

In web streaming, the size of video rendered on screen may be influenced by a number of factors, such as the layout of a web page embedding the video, the position and size of the web browser window, and the resolution of the screen. During the playback, the adaptive streaming players, usually select one of the available encoded streams (renditions) to pull and render on the screen. Such selection is typically done based on the available network bandwidth, and also based on the size of the player window. Typically, the logic of matching video stream to be played to the size of the window is very simplistic, considering only pixel dimensions of the video. However, with vastly different video playback devices, their pixel densities and other parameters influencing the Quality of Experience (QoE), the reliance of pixel matching is bound to be suboptimal. A better approach must use a proper QoE model, considering parameters of viewing setup on each device, and then predicting which encoded resolution, given player window and other constraints would achieve best quality. In this paper, we adopt such a model and develop an optimal rendition selection algorithm based on it. We report results by considering several different categories of receiving devices (HDTV, PCs, tablets and mobile) and show that optimal selections in all those cases will be considerably different.