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.
This trades off quality for reliability, but Adaptive Bit Rate Streaming achieves both by varying the quality to suit conditions, always delivering pictures even if the quality drops. This enables the internet to work more like a broadcast TV service, so that people can start playing a video almost instantly without having first to wait for buffers to fill.
As a result, Adaptive Bit Rate Streaming is now being adopted for delivery of video to PCs and other fixed internet connected devices as well as mobiles. It optimizes quality and fits well with the changes in Internet structure being driven by video and in particular the needs of live broadcast where many people want to watch the same content, according to Mike Nann, director of marketing at Digital Rapids, a vendor of video transmission technology.
“Adaptive Bit Rate Streaming is already associated with moving content closer to the consumption point, as it leverages existing web infrastructure and the vast network of HTTP caches already deployed for serving Web pages worldwide,” said Nann. Adding video is then largely a matter of scaling the capacity, while implementing the appropriate Adaptive Bit Rate Streaming software.
The main emerging Adaptive Bit Rate Streaming techniques using HTTP include Microsoft IIS Smooth Streaming and Adobe’s HTTP Dynamic Streaming. But as Nann added, “while these two technologies get much of the attention for Web delivery, they aren’t the only technologies that are using HTTP to adaptively reach viewers – there are numerous others, as well as adaptive streaming capabilities incorporated within broader service offerings.”
Although Adaptive Bit Rate Streaming is the key to effective distribution of popular video content including mass live streaming events like major concerts, it is not the only show in town, being less efficient for niche material with small audiences. “It isn’t going to be used all the time for the small-audience and lower-value use cases that are the majority of online streaming,” said Nann.
This is partly because Adaptive Bit Rate Streaming is costly to deploy and so only worth it when the audience and revenue are relatively large. “While deploying ABRS offers cost savings for scaling the delivery infrastructure, it is more expensive at various points in the chain,” said Nann. In particular there are increased processing requirements to create the multiple streams at different bit rates, coupled with additional storage and management requirements for handling on-demand content, which will have to be held at different locations for delivery over a wide area.
Currently only 1 percent of internet traffic is distributed via Adaptive Bit Rate Streaming, but this is likely to increase rapidly to at least 30 percent and possibly 50 percent or more over the next two years.