Media Server
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A media server is a computing device, ranging from an enterprise class machine providing video on demand, to, more commonly, a small home computer storing various digital media.
[edit] Purpose
In a home setting, a media server acts as an aggregator of information: video, audio, photos, books, etc. These different types of media (whether they originated on DVD, CD, digital camera, or in physical form) are stored on the media server's hard drive. Access to these is then available from a central location. The media server usually connects to a large HDTV and is run using a remote instead of the traditional mouse and keyboard. Special software and operating systems, such as Microsoft Windows Media Center Edition, provide the user interface necessary to support remote control. Media Server is also a component of a VoIP (Voice Over IP) network which provides media processing functions, such as audio announcements, IVR (Interactive Voice Response), and multimedia conferencing.
[edit] Hardware
An obvious requirement of the media server is a large hard disk drive or array. As of 2006, media servers are available with storage in the terabyte range. Also required are audio/video inputs and outputs, much like those that would be found in a traditional A/V receiver. To output high definition content, component, DVI, or HDMI connectors are required. HDMI is the connector of choice, as it carries both video and audio in one cable, and also supports the latest DRM encryption scheme, HDCP. While some DVI connectors do support DRM, they do not carry audio information, requiring a fiber optic or digital coaxial cable to support surround sound. In addition to this, network support is often included, as this allows any connected devices to access the media server (indeed, Microsoft's Origami is rumored to be an add-on product to its Media Center operating system).
A media server provides building blocks for the feature server and application server to use.
Typical building blocks include announcements, interactive voice response (IVR), conferencing (or bridging), play and record, speech recognition, text-to-speech, and facsimile. These building blocks are generic and can be applied, unchanged, to a large variety of services.
A media server’s building blocks are used by application service logic in an application server or softswitch to provide services requiring interaction with the media or bearer path. When an application requires media processing, it instructs the media server and far-end devices to set up connections to each other and then invokes one or more building blocks on the connection(s). When the need for media processing is finished, the application can withdraw the media server from the connection(s).
There is agreement that the media server should not maintain any call state or feature/application logic in the network. It serves instead as a service device, used as needed by network elements that do have the feature or application logic within them.
