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In broadcasting, channel playout is the generation of the source signal of a radio or television channel produced by a broadcaster, coupled with the transmission of this signal for primary distribution or direct-to-audience distribution via any network. Such radio or television distribution networks include terrestrial broadcasting (analogue or
digital radio Digital radio is the use of digital technology to transmit or receive across the radio spectrum. Digital transmission by radio waves includes digital broadcasting, and especially digital audio radio services. Types In digital broadcasting s ...
), cable networks,
satellites A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
(either for primary distribution intended for
cable television headend A cable television headend is a master facility for receiving television signals for processing and distribution over a cable television system. A headend facility may be staffed or unstaffed and is typically surrounded by some type of security ...
s or for direct reception, DTH / DBS),
IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded medi ...
, OTT Video, point-to-point transport over managed networks or the public Internet, etc. The television channel playout happens in
master control Master control is the technical hub of a broadcast operation common among most over-the-air television stations and television networks. It is distinct from a production control room (PCR) in television studios where the activities such as swit ...
room (MCR) in a playout area, which can be either situated in the
central apparatus room In broadcast facilities and television studios, a central apparatus room (CAR, pronounced "C-A-R"), central machine room, or central equipment room (CER), or central technical area (CTA), or rack room is where shared equipment common to all techn ...
or in purposely built playout centres, which can be owned by a broadcaster or run by an independent specialist company that has been contracted to handle the playout for a number of channels from different broadcasters. Some of the larger playout centres in Europe, Southeast Asia and the United States handle well in excess of 50 radio and television "feeds". Feeds will often consist of several different versions of a core service, often different language versions or with separately scheduled content, such as local opt outs for news or promotions.


Playout systems

Centralcasting In terrestrial radio and television broadcasting, centralcasting refers to the use of systems automation by which customised signals for broadcast by multiple individual stations may be created at one central facility. Definition Centralcasti ...
is multi-channel playout that generally uses
broadcast automation Broadcast automation incorporates the use of broadcast programming technology to automate broadcasting operations. Used either at a broadcast network, radio station or a television station, it can run a facility in the absence of a human oper ...
systems with
broadcast programming Broadcast programming is the practice of organizing or ordering (scheduling) of broadcast media shows, typically radio and television, in a daily, weekly, monthly, quarterly or season-long schedule. Modern broadcasters use broadcast automation ...
applications. These systems generally work in a similar way, controlling
video server {{refimprove, date=September 2014 A video server is a computer-based device that is dedicated to delivering video. Video servers are used in a number of applications, and often have additional functions and capabilities that address the needs of p ...
s,
video tape recorder A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were us ...
(VTR) devices, Flexicarts, audio
mixing console A mixing console or mixing desk is an electronic device for mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals from electric or electronic instr ...
s,
vision mixer A vision mixer is a device used to select between several different live video sources and, in some cases, compositing live video sources together to create visual effects. In most of the world, both the equipment and its operator are called ...
s and video routers, and other devices using a
serial communications In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are s ...
9-Pin Protocol (
RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' ('' data terminal equipment'') suc ...
or
RS-422 RS-422, also known as TIA/EIA-422, is a technical standard originated by the Electronic Industries Alliance that specifies electrical characteristics of a digital signaling circuit. It was meant to be the foundation of a suite of standards that ...
). This provides deterministic control, enabling frame accurate playback,
Instant replay Instant replay or action replay is a video reproduction of something that recently occurred which was both shot and broadcast live. The video, having already been shown live, is replayed in order for viewers to see again and analyze what had ...
or video switching. Many systems consist of a front end operator interface on a separate platform to the controllers – e.g. a Windows
GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inst ...
will present a friendly easy to use method of editing a playlist, but actual control would be done on a platform with a
real-time operating system A real-time operating system (RTOS) is an operating system (OS) for real-time applications that processes data and events that have critically defined time constraints. An RTOS is distinct from a time-sharing operating system, such as Unix, which m ...
such that any large-scale playlist amendments do not cause delays to device control. Most broadcast automation systems will have a series of common device drivers built in, for example Sony VTR control (aka Sony Serial), Louth Video Disk Control Protocol (VDCP, a proprietary communications protocol), General Purpose Interface (GPI), or Grass Valley Group M21 Master Control. This ensures that a broadcast automation system bought "off the shelf" will at least be able to ingest and playout content, although may not be able to take advantage of more efficient methods of control. Most server, and especially most
digital on-screen graphic A digital on-screen graphic, digitally originated graphic (DOG, bug, or network bug) is a watermark-like station logo that most television broadcasters overlay over a portion of the screen area of their programs to identify the channel. They are ...
and
character generator A character generator, often abbreviated as CG, is a device or software that produces static or animated text (such as news crawls and credits rolls) for keying into a video stream. Modern character generators are computer-based, and they can ...
(CG) manufacturers will have a specific
device driver In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and ot ...
for their device, with increasing degrees of complexity, and different automation companies will include these drivers to enhance their product or to fit a customers need. This is the "traditional" method of playout automation, where there are multiple devices. Some modern automation systems use a unified playout method, where the broadcast server fulfills the functions of multiple devices as a self-contained system, like the PlayBox Technology channel-in-a-box.


Playout devices

Playout will usually involve an
airchain In broadcast engineering for radio or television, the airchain or transmission chain (UK) (sometimes air chain (US) or just chain (UK)) is the path or route an audio or video signal takes on its way through a radio station or television station. ...
of devices which begin with content, typically stored on
video server {{refimprove, date=September 2014 A video server is a computer-based device that is dedicated to delivering video. Video servers are used in a number of applications, and often have additional functions and capabilities that address the needs of p ...
s, and ultimately an output, either as an (
Asynchronous serial interface Asynchronous Serial Interface, or ASI, is a method of carrying an MPEG Transport Stream ( MPEG-TS) over 75-ohm copper coaxial cable or optical fiber. It is popular in the television industry as a means of transporting broadcast programs from the st ...
) (ASI) / IP or ( Serial Digital Interface) (SDI) for on pass to a distribution company. The devices in the chain depend on the service required under the contract with the Channel. Typically a standard television channel would require a
Master Control Master control is the technical hub of a broadcast operation common among most over-the-air television stations and television networks. It is distinct from a production control room (PCR) in television studios where the activities such as swit ...
, Video switcher, and/or a Video router to allow switching of live sources. This video switcher may include other functions such as
keying (graphics) Compositing is the process or technique of combining visual elements from separate sources into single images, often to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously ca ...
(also known as Down Stream Keyers), Audio Overs for mixing in
voice over Voice-over (also known as off-camera or off-stage commentary) is a production technique where a voice—that is not part of the narrative (non-diegetic)—is used in a radio, television production, filmmaking, theatre, or other presentations. ...
s (VO) or announcements, and facilitate transitions between events, such as a fade through black or crossfade (also known as mix). Other devices include: Graphics inserters – At least one Graphics inserter, or one with several layers. This allows for
Station identification Station identification (ident, network ID or channel ID or bumper) is the practice of radio and television stations and networks identifying themselves on-air, typically by means of a call sign or brand name (sometimes known, particularly in the ...
/Logo/
Digital on-screen graphic A digital on-screen graphic, digitally originated graphic (DOG, bug, or network bug) is a watermark-like station logo that most television broadcasters overlay over a portion of the screen area of their programs to identify the channel. They are ...
(Dog or Bug) insertion, and can also be used for
end credits Closing credits or end credits are a list of the cast and crew of a particular motion picture, television program, or video game. Where opening credits appear at the beginning of a work, closing credits appear close to, or at the very end of a ...
sequences, coming next graphics or programme information straps Subtitling inserters – This can be either closed or open – i.e. in vision as a graphic for all to see, or closed either as an MPEG stream item,
Closed Captioning Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio po ...
or
World System Teletext World System Teletext (WST) is the name of a standard for encoding and displaying teletext information, which is used as the standard for teletext throughout Europe today. It was adopted into the international standard CCIR 653 (now ITU-R BT.653) ...
. Audio servers – An audio playout system would provide scheduled voiceovers Aspect Ratio Converters – These alter the picture shape or send an embedded signal to allow the material format to be displayed correctly on a particular feed (e.g. Widescreen on a standard non-widescreen Analogue terrestrial feed) Some of these more advanced devices require information from the playlist, and so do not tend to use an RS422/232 driver, but a complex XML based system which allows for more complex metadata to be passed, e.g. a "Now" or "Next" Graphic can be created from a template using text information from the playlist.


Channel-in-a-box concept

With the "softwarization" of the various functions required to generate the channel signal in a playout system, the possibility to gather all of them into a single piece of equipment became possible. Such all-in-one video playout servers are known as channel-in-a-box systems.


Playout Centers

Playout is one of the basic infrastructure of a playout center. Mostly called as channel in a box server, but basically composed of playout servers with integrated graphics and IP or ASI output. Aim of playout centers is mostly to serve customers a simple file based television facility. Up-link and TV Channel in a box servers simply provide the facility.


Scheduling

The playout system execute a scheduled and time-accurate playlist of content to generate a linear radio or television signal (or "feed"). Within that playlist, there is the content that goes "on-air": live or recorded shows/programs, ad breaks, auto-promo clips, etc.


Workflow

A common workflow is for the broadcast automation system to have a recording schedule to ingest material from a satellite or line feed source and then time-shift that material based on a playlist or schedule. The playout schedule will have been created in the customer's
broadcast programming Broadcast programming is the practice of organizing or ordering (scheduling) of broadcast media shows, typically radio and television, in a daily, weekly, monthly, quarterly or season-long schedule. Modern broadcasters use broadcast automation ...
scheduling system and exported into a format suitable to be used in the Playout system. There is a move to SMPTE-22, known as Broadcast Exchange Format (BXF) to try to standardise the messaging involved in this interaction. The resulting playlist is "loaded" into the appropriate channel of the broadcast automation system in advance of the transmission time. Various processes will take place to ensure the content is available on the correct servers for playout at the right time, typically this involves advance requests to move material from deep storage such as Tape Archives or FTP Clusters to Broadcast Video servers, often using FTP. On playing out the material, the audio and video signals are usually transported from the playout area to the network via a
studio/transmitter link A studio transmitter link (or STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is ac ...
(STL), which may be fibre backlink, microwave or satellite uplink. Playout is often referred to as ''Presentation'' or ''Transmission (TX)'', and is under control of an automatic transmission system.


See also

*
Broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...


References

{{Analogue TV transmitter topics Broadcast engineering Television terminology it:Emissione