A client device adaptively streams a 360-degree video. A first segment is displayed based on a first viewing direction at a first time, where the first viewing direction is associated with a first viewport. The client requests a first base buffer segment based on the first viewport. The first base buffer segment has a presentation time after the first segment. At a second time, the viewing direction changes to a second viewing direction associated with a second viewport. The client requests, prior to the presentation time, a first viewport buffer segment based on the second viewport, with the same presentation time. The client device displays a second segment at the presentation time, wherein the second segment is either the first viewport buffer segment or the first base buffer segment. The client provides reports on viewport switching latency and on the most-requested segments.