DASH: Adaptive Streaming over HTTP

Video streaming has become one of the most prominent Internet applications. And more recently, with the introduction of a variety of smartphones and tablets, video streaming over wireless networks has also become an important application.

Wireless data transmissions are subject to significantly higher variations in bandwidth and delay compared to similar transmissions via a wired network. Qualcomm’s Adaptive Streaming R&D project aims to enhance the user experience with video streaming over a wireless connection, by seamlessly adapting the video quality and bit rate according to available bandwidth, device capability and content characteristics. Qualcomm’s solution is based on the DASH (Dynamic Adaptive Streaming over HTTP) standard from MPEG and 3GPP. Recently, the DASH Promoters Group was formed by several companies, including Qualcomm, to facilitate the adoption of the DASH standard.

Increasingly, video is being watched on mobile devices. People are interested in watching movies, sports highlights and news updates wherever they are. In addition, operators and content publishers are making high value content such as sports, concerts, movies and other forms of video available to mobile devices.

Adaptive streaming helps enhance the user experience by adapting the requested video quality based on available bandwidth, device capability and other factors. Compared to traditional video streaming, which requires dedicated streaming servers, HTTP-based adaptive streaming can use off-the-shelf web servers and benefit from the scale of content distribution networks. Adaptive delivery allows for graceful improvement or degradation of video quality without stoppage under varying channel conditions, and can be used to handle different types of wireless connections including 3G, 4G, and Wi-Fi.

Qualcomm's adaptive streaming team is fully engaged in the R&D and commercialization of adaptive streaming technologies based on the newly standardized MPEG DASH (Dynamic Adaptive Streaming over HTTP) standard. Our efforts cover the following aspects: 1) Client-side algorithm design for video quality adaptation; 2) Performance measurement and evaluation of adaptively streamed video; 3) Bringing adaptive streaming into Android Platform; 4) Standardization of adaptive streaming protocols – MPEG DASH; and 5) Methods to enhance the reliability and efficiency of adaptive delivery.

The available bandwidth experienced by a mobile device can change precipitously. Instead of downloading a video encoded at a low fixed bit rate, Qualcomm’s adaptive streaming client algorithm will continuously monitor available bandwidth and adapt the requested video bit rate to maximize the user experience in such a way that the video quality is sustainably high, while stalls and jitter are minimized.