An IPTV service, typically distributed by a service provider, delivers live TV programs or on-demand video content. An IPTV system may be used to provide video content over a private network in an enterprise, although such implementations are far less common than subscriber-based models due to complexity and scaling issues.
How does IPTV work?
IPTV content is often delivered over a managed or dedicated network. Compared to the public Internet, a private network gives network operators more control over the video traffic and, by extension, the ability to ensure quality of service (QoS), uptime and reliability.
In traditional television delivery, all programming is broadcast simultaneously. The available program signals flow downstream, and the viewer selects a program by changing the channel.
An IPTV service, by contrast, sends only one program at a time. Content remains on the service provider's network, and only the program the customer selects is sent to the residence. When a viewer changes the channel, a new stream is transmitted from the provider's server directly to the viewer. Like cable TV, IPTV requires a set-top box or other customer-premises device.
IPTV primarily uses IP multicasting with Internet Group Management Protocol (IGMP) for live television broadcasts and Real-Time Streaming Protocol (RTSP) for on-demand programs. Other common protocols include Real-Time Messaging Protocol (RTMP) and Hypertext Transfer Protocol (HTTP).
Types of IPTV
The use of IP also enables providers to support various other services and applications, such as video on demand, in-program messaging and timeshifting, a broad term for services that allow viewers to consume content other ways besides live broadcasts (e.g., digital recording, on-demand video and the ability to rewind or restart a live program already in progress).
IPTV competes with another delivery model known as Internet TV, which refers to television content distributed through a website.
IPTV providers include a wide range of companies from large network operators like Verizon with its FiOS services and massive companies like Google, Apple and Microsoft, to vendors that include Sony, and a wide variety of smaller or niche companies sometimes specializing in certain types of content delivered over a broadband IP connection.