Dynamic bit-rate adaptation as a best practice
February 1, 2010
If providing multimedia content via ubiquitous, superior streaming to mobile phones is the challenge, one necessity is dynamic bit-rate adaptation (DBRA): a network’s ability to dynamically adjust the content quality or size to varying network conditions.
With network deployment of wireless data infrastructure continuing to accelerate, promising wide mobile broadband coverage and, in turn, seamless delivery of multimedia content, the cost and complexity of fulfilling any content, any screen expectations have only grown more apparent. The variety of devices, formats and networks and the limits to quality-of-service supported in wireless networks stands in the way of accessing rich multimedia content from the Internet and TV environments. Reaching that high-quality user experience means that operators must deal with both network congestion and fragmentation.
When the video connection is initialized, a DBRA-capable network uses monitored bandwidth metrics data that relies on available bandwidth, jitter, bit rate and packet loss to adapt the stream quality dynamically by negotiating a transmission rate based on the evaluation of the connection’s real-time quality. If the connection quality deteriorates, DBRA lets the network negotiate a lower-transmission bit rate and incrementally increases it when conditions improve, all in real time. That’s how DBRA optimizes video streaming quality on the fly.
DBRA delivers a “bit-by-bit”’ or “frame-by-frame” maximum available user experience on the network at any given time. Because the video stream’s output is directly linked to the network’s current conditions, maintaining a smooth, coherent viewing experience requires data to reach the mobile unit at a constant rate. DBRA accomplishes this constancy through heuristic algorithms that deliver pattern-matching capabilities predictively, changing the bit rate before any perceptible changes in quality for the end users.
Patrick Lopez is CMO at Vantrix.