Adaptive bit rate streaming, content caching, and other techniques are great ways to improve the quality of real-time services, but they all fail when they eventually encounter congestion. These techniques need to be combined with quality of service markings to ensure that real-time traffic is prioritized before non-real-time traffic like common web browsing. Once differentiated services are offered, consumers will have a true choice of content providers from traditional voice and video distributors.
Philip Hunter, Reporter, BroadbandBreakfast.com
LONDON, October 1, 2010 – With online video now the main cause of internet bottlenecks and consumer frustration over poor performance, new ways are emerging to provide better picture quality within limited bandwidth under the banner of Adaptive Bit Rate Streaming.
Various versions of this technology already have been deployed for mobile TV transmission, where bandwidth is even more limited. For example, by Apple with HTTP Live Streaming for iPhone, and by Google in its Android mobile operating system. Microsoft Windows Phone 7 scheduled for an October launch also incorporates a form of Adaptive Bit Rate Streaming.
The idea is simple and old – encoding video at a variety of bit rates to suit different quality requirements and consumer display capabilities, and then break the bit streams into small chunks that can be delivered more efficiently. But the new development is to make this work better for high bit rate video transmission, and above all do it via HTTP (Hypertext Transfer Protocol), the linchpin of communications over the World Wide Web. Adaptive Bit Rate Streaming adds the key quality component for video, enabling HTTP to cope with the limited bandwidth available at various points of the internet delivery chain.
The delivery of video in small chunks also allows adjustment in real-time to deliver the best pictures that the bandwidth will allow at any given moment. By contrast, the preceding technique of progressive downloading assumes the worst and delivers video only at the quality supported by the minimum bandwidth available, making use of any temporary boost in capacity to get ahead and deliver video that the viewer has not yet watched.
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