Architecture of IPTV
Architecture of a Video Server Network
Depending on the network architecture of the Service Provider, there are two main types of Video Server architectures that can be considered for IPTV deployment, Centralized, and Distributed.
The Centralized Architecture model is a relatively simple and easy to manage solution. For example, as all contents are stored in Centralized servers, it does not require a comprehensive content distribution system. Centralized Architecture is generally good for a network that provides relatively small VOD service deployment, has adequate core and edge bandwidth and has an efficient Content Delivery Network (CDN).
A Distributed Architecture is just as scalable as the Centralized model, however it has bandwidth usage advantages and inherent system management features that are essential for managing a larger server network. Operators who plan to deploy a relatively large system should therefore consider implementing a Distributed Architecture model right from the start. Distributed Architecture requires intelligent and sophisticated content distribution technologies to augment effective delivery of multimedia contents over service provider's network

DEFINITION OF IPTV AND INTERNET TV

IPTV and Internet TV
A telco IPTV service is usually delivered over a complex and investment heavy walled garden network, which is carefully engineered to ensure bandwidth efficient delivery of vast amounts of multicast video traffic. The higher network quality also enables easy delivery of high quality SD or HD TV content to subscribers’ homes. This makes IPTV by default the preferred delivery platform for premium content. However the investment for a telco to build an end-to-end IPTV service can be substantial.
By contrast "Internet TV" generally refers to transport streams sent over IP networks (normally the Internet) from outside the network that connects to the users premises. An Internet TV provider has no control over the final delivery and so broadcasts on a "best effort" basis. Elementary streams over IP networks and proprietary variants as used by websites such as YouTube are now rarely considered to be IPTV services.
Compared to telco IPTV, Internet TV is a quick-to-market and relatively low investment service. Internet TV rides on existing infrastructure including broadband, ADSL, Wi-Fi, cable and satellite which makes it a valuable tool for a wide variety of service providers and content owners looking for new revenue streams. However, due to the fact that IPTV is always delivered over low cost IP STBs, which have limited computing power, the capability for IPTV operators to provide diverse multimedia services is limited. This is where Internet TV has an advantage as it is delivered to a subscriber's (generally) powerful PC.
The relative ease of establishing an Internet TV service seems at first a threat to telco IPTV operators’ multimillion dollar investment, but both services do not necessarily compete for the same customers and there are some synergies between the two such as a common technology platform in the form of web-based technologies for content storage and delivery.
Broadcast IPTV has two major architecture forms: free and fee based. As of June 2006, there are over 1,300 free IPTV sources available.[10] This sector is growing rapidly and major television broadcasters worldwide are transmitting their broadcast signal over the Internet. These free IPTV sources require only an Internet connection and an Internet enabled device such as a personal computer, HDTV connected to a computer or even a 3G cell/mobile phone to watch the IPTV content. Various Web portals offer access to these free IPTV sources. Some cite the ad-sponsored availability of TV series such as Lost as indicators that IPTV will become more prevalent.
Because IPTV uses standard networking protocols, it promises lower costs for operators and lower prices for users. Using set-top boxes with broadband Internet connections, video can be streamed to households more efficiently than current coaxial cable. ISPs are upgrading their networks to bring higher speeds and to allow multiple High Definition TV channels.
IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software (much like a cable or DSS box) that can handle viewer requests to access to many available media sources.
Local IPTV, as used by businesses for Audio Visual AV distribution on their company networks is typically based on a mixture of: a) Conventional TV reception equipment and IPTV encoders b) IPTV Gateways that take broadcast MPEG channels and IP wrap them to create multicast streams.

IPTV

Markets
While all major western countries and most developed economies have IPTV deployments, the world's leading markets for IPTV for now are France (led by Free, then Orange, then Neuf Cegetel; total of over 4 million subscriptions), South Korea (1.8 million subscriptions), Hong Kong, Japan, Italy, Spain, Belgium, China, Switzerland and Portugal. Services have also launched in Slovenia, Romania, Croatia, Serbia, Montenegro, Scandinavia and, with two competing players, Iceland. The United Kingdom launched IPTV early but has been slow to grow. IPTV is just beginning to grow in Central and Eastern Europe,now it is growing in South Asian countries such as Sri Lanka, Pakistan and especially India.[8] but significant plans exist in countries such as Poland and Russia.
The first IPTV service to launch on the Chinese mainland sells under the "BesTV" brand and is currently available in the cities of Shanghai and Harbin.[9]