Media Flow Controller Overview : Media Flow Controller Functions : SmoothFlow™

SmoothFlow™ refers to the Quality of Experience (QoE) feature that Juniper Networks Media Flow Controller can provide to viewers for uninterrupted video viewing. Last-mile bandwidth fluctuations can cause buffering, or long pauses. Juniper Networks SmoothFlow technology provides viewers a TV-like video viewing experience irrespective of last-mile bandwidth fluctuations, by dynamically detecting available bandwidth and seamlessly switching the bit-rate of a video being progressively downloaded over HTTP. Viewers with high bandwidth connections receive videos at higher quality resolutions while viewers with lower bandwidth connections receive videos encoded at bit-rates matching their available bandwidth. Media Flow Controller always sends video data at the bit-rate that is appropriate to the available bandwidth between the server and client at any point of time.
Media Flow Controller SmoothFlow receives client-side signals from the client player providing information about real-time resource utilization (for example, if the viewer starts a CPU-intensive application while watching a video). In addition to SmoothFlow, such signals enable Media Flow Controller to allow viewers to control their media playback experience using flow commands such as fast forward, rewind, frame step, pause, etc., on a video that is currently being downloaded.
Media Flow Controller server-side intelligence, coupled with player feedback, allows Juniper Networks Media Flow Controller to deliver a really high quality of viewing experience tailored specifically to each viewer. Figure 4, next, illustrates a SmoothFlow deployment.
Figure 4 SmoothFlow™ Deployment Overview
How SmoothFlow Works
SmoothFlow is based on a dual channel approach where one channel is used for video delivery, and the other for control purposes to signal to Media Flow Controller adaptation points for responding to bandwidth fluctuations. SmoothFlow technology is delivered via progressive download over HTTP, providing the additional benefit that the consumer does not need to download a custom player. As shown in Figure 4:
Content providers decide how many bit-rate profiles (differently encoded versions) of any one video they want to create. Each set of encoded bit-rate profiles must include a metadata file describing how many bit-rate profiles a video has and where they are stored; this file may be created by the provider, or auto-created, depending on the encoding procedure used. Together, the bit-rate profiles and the description file are the “asset.” Once the assets are created, they are pre-staged to an origin server, typically via FTP.
Next the publisher or encoder sends a properly configured Media Flow Controller a SmoothFlow processing request for the asset. This may be done with a script, depending on the encoding procedure used.
SmoothFlow reads the data file given in the processing request, obtains the video files, and processes them for delivery; this includes chunking the different bit-rate profiles, creating the internal metadata file for Media Flow Controller, and queuing the assets on the origin server.
Assets are delivered to the edge either upon cache miss or via a SmoothFlow virtual player. As the assets are delivered to the client players over the delivery channel, feedback hints to SmoothFlow are sent over the control channel telling Media Flow Controller when to switch to a different bit-rate profile.

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