Editing Video server (section)

==Video broadcast and production==

[[File:XT2 SERVER.jpg|thumb|A video replay server, commonly used to provide instant replay in broadcasts of sporting events (EVS XT2)]]
[[File:Emulab-cluster2-back.jpg|thumb|Large online providers of video on-demand employ clusters of servers such as this to simultaneously output multiple streams (Emulab)]]
In TV [[broadcast]] industries, a server is a device used to store broadcast quality images and allows several users to edit stories using the images they contain simultaneously.

The video server can be used in a number of contexts, some of which include:

* News: providing short news video clips as part of a news broadcast as seen on networks such as [[CNN]], [[Fox News]] and the [[BBC]].
* Production: enhance live events with [[instant replays]] and [[slow motion]] and highlights (sport production) (see [[Outside broadcasting|OB Vans]])
* Instruction: delivering course material in video format.
* Public Access: delivering city specific information to residents over a cable system.
* Surveillance: deliver real-time video images of protected site.
* Entertainment: deliver anything used for entertainment. It can be gaming, news, movie trailers, or movies.

A professional-grade video server performs recording, storage, and [[playout]] of multiple video streams without any degradation of the video signal.  [[Broadcast quality]] video servers often store hundreds of hours of compressed audio and video (in different [[codecs]]), play out multiple and synchronised simultaneous streams of video by, and offer quality interfaces such as [[Serial digital interface|SDI]] for digital video and XLR for balanced analog audio, [[AES/EBU]] digital audio and also [[Time Code]].  A [[genlock]] input is usually provided to provide a means of synchronizing with the house reference clock, thereby avoiding the need for [[timebase correction]] or [[frame synchronizer (video)|frame synchronizers]].

Video servers usually offer some type of control interface allowing them to be driven by [[broadcast automation]] systems that incorporate sophisticated [[broadcast programming]] applications.  Popular protocols include [[VDCP]] and the [[9-Pin Protocol]].

They can optionally allow [[direct to disk recording]] using the same [[codec]] that is used in various [[post-production]] [[video editing software]] packages to prevent any wasted time in [[transcoding]].

=== Features ===

Typically, a video server can do the following:

* Ingest of different sources : [[video cameras]] (multiple angles), [[satellite]] [[data feed]]s, [[disk drives]] and other video servers. This can be done in different [[codecs]].
* Temporary or definitive storage of these video feeds.
* Maintain a clear structure of all stored media with appropriate [[metadata]] to allow fast search : name, remarks, rating, date, [[time code]], etc.
* [[video editing]] of the different [[digital video|clips]]
* Transfer those [[digital video|clips]] to other video servers or [[playout]] directly (via [[Internet Protocol|IP]] interface or SDI)
 
Generally, they have several bi directional channels (record and ingest) for video and audio. A perfect synchronisation is necessary between those channels to manage the feeds.