Caching in HTTP Adaptive Streaming: Friend or Foe?

Video streaming is a major source of Internet traffic today and usage continues to grow at a rapid rate. To cope with this new and massive source of traffic, ISPs use methods such as caching to reduce the amount of traffic traversing their networks and serve customers better. However, the presence of a standard cache server in the video transfer path may result in bitrate oscillations and sudden rate changes for Dynamic Adaptive Streaming over HTTP (DASH) clients. In this paper, we investigate the interactions between a client and a cache that result in these problems, and propose an approach to solve it. By adaptively controlling the rate at which the client downloads video segments from the cache, we can ensure that clients will get smooth video. We verify our results using simulation and show that compared to a standard cache our approach (1) can reduce bitrate oscillations (2) prevents sudden rate changes, and compared to a no-cache scenario (3) provides traffic savings, and (4) improves the quality of experience of clients.