An HTTP/2 Push-Based Approach for SVC Adaptive Streaming

HTTP Adaptive Streaming (HAS) is becoming the de-facto standard for over-the-top video streaming. In HAS, video content is encoded at multiple quality levels and temporally divided into multiple segments. The client can control the streaming session, by selecting the quality level for every video segment, allowing a smoother playback and a better Quality of Experience (QoE) for the user. Although results are promising, current solutions often suffer from high round-trip-time (RTT) cycles in mobile networks. This is especially true for scalable video coding (SVC), where the client decodes higher quality levels in combination with lower ones: multiple requests are required to retrieve a single video segment, which makes the approach more susceptible to high RTTs. Meanwhile, the IETF has standardized the HTTP/2 protocol, which provides new features that allow a reduction of the page load time in web browsing. In this paper, we propose to use the new server push feature of HTTP/2 to actively push the base layer of live, SVC-encoded content from server to client. This allows to eliminate at least one idle RTT cycle for every video segment, which has a potentially significant impact on the QoE of the user. By evaluating the proposed approach through emulation, we show that an improvement can be achieved for the average video quality in high-RTT networks. Furthermore, we show that the startup time of the client can actively be reduced with one RTT.