Cloud playout is software, running on servers in the cloud, that plays out a TV channel's schedule of programmes and ads to the second, 24 hours a day. Playout is the last step inside a broadcaster before the channel leaves for viewers. It used to run on special machines in a broadcaster's own building. Now it often runs on rented cloud servers; see cloud computing. Many of the free channels on smart TVs, called FAST channels, are run this way.
What does playout do? A channel's schedule is a list of every item that will go on air: each programme, each ad break, each ad and each promotion, with its exact start time. The schedule is called a playlist. The playout software reads the playlist and plays each video file at its planned second. It switches to live feeds, such as a news studio or a match, when the playlist says so. It adds the channel's logo in a corner, the subtitles, and graphics such as "coming up next". It also inserts markers at the start and end of each ad break. Later systems use these markers to replace the ads, for example with different ads for viewers who stream the channel; see server-side ad insertion (SSAI).
Take, for example, a Punjabi music channel based in Mohali. Its schedule for one day has 1,440 minutes of airtime: music videos, two live request shows, and 96 ad breaks. At 8:29:30 pm, a music video ends. At exactly 8:30:00, the playout software starts a three-minute ad break of six 30-second ads, in the order the sales team booked. At 8:33:00 it switches to the live request show from the studio, and puts the show's title on screen. The channel runs from servers in two different cloud regions. If the first copy fails, the second copy is already playing the same playlist, and it takes over within a second.
Why move playout to the cloud? A broadcaster does not have to buy machines for each channel, or keep a building full of them. A new channel can be started in days, by setting up one more copy of the software. A broadcaster can also make a special version of a channel, such as one for a FAST service in another country, without new hardware.
Playout receives its live feeds through a broadcast video router, and its schedule from the television network that owns the channel. Its output is compressed by video encoding software before it goes to satellites, cable operators and streaming services. On smart TVs, FAST channels appear in the TV's operating system like ordinary channels. While the channel is on air, broadcast monitoring checks every second of its output.