OTT Streaming by: Lionel Bringuier, CTO, Anevia What is Over The Top streaming?
OTT streaming, where OTT stands for “over the top”, is the delivery of video and audio media streams to connected devices via the Internet. Unlike traditional IPTV, there is no need for a dedicated network or infrastructure provided by the operator, as OTT is transported through regular Internet data protocols and uses the open Internet, on unmanaged networks. What is the difference between OTT and IPTV?
By IPTV, we mean traditional IPTV which has been widely deployed by numerous operators, namely those that propose a triple-play ADSL offer to their customers.
This traditional IPTV is delivered over a dedicated, operator-managed network that is used only for broadcasting TV. The operator has full control over the network and can configure certain parameters, such as bandwidth consumption and regularity of packet transportation, to ensure a high level of service quality. Traditional IPTV uses TS (transport stream) transmission technology which is based on satellite TV broadcasting and delivers content over UDP in datagram mode.
OTT TV uses HTTP, the protocol which has been used for decades to transport web pages over the Internet. HTTP is based on TCP, a connected transport protocol with more practical features than UDP. It is easier to track a TCP connection, for example. As a result, a TCP connection is easily managed through firewalls, NAT (network address translation), home and office networks. It also enables anyone that has sufficient web hosting capacity to broadcast any audio and video media to a worldwide audience over the open Internet.
HTTP has already been used as a transport solution for video on demand media embedded into web pages, especially on Flash-based sites, such as YouTube or Dailymotion. However this solution does not use real time streaming, but progressive downloading of one media file, where the browser downloads the file from the HTTP web server and when it has a sufficient amount of data, starts to play the content while downloading the rest of the file. The main drawback to this approach is the length of time it takes to fill the initial buffer. Another issue associated with http is streaming quality, which depends on the IP connection. Content streaming may be subject to stalling if there are fluctuations in bandwidth, leading to frame freezing. As a consequence, it is nearly impossible to use the solution to broadcast live channels.
Until recently, live broadcasting was therefore restricted to operator-managed IPTV networks using the UDP multicast protocol. The arrival of OTT streaming, however, has brought a new approach and it is now possible to achieve levels of streaming quality over HTTP that allow live content to also be broadcast over the Internet. What are the challenges in streaming content OTT?
If we take into account the principles described above, we can sum up the challenges faced by OTT service providers as follows:
- Video and audio content should be available wherever the Internet is accessible. HTTP must therefore be used as the transport protocol for these types of content;
- It should be used for live TV broadcasting as well as for VOD content;
- As the open Internet is by definition an “unmanaged” network, the end-user bandwidth cannot be controlled. This can lead to low streaming quality and negatively impact the user experience when watching TV. This issue is of particular importance for mobile networks;
- The proposed technology must be adapted for use on a full range of end-user devices (PC web browsers, STB/TV, mobile handsets, digital tablets, etc). This means it must be light on system resources and easy to install;
- It should also be easy to integrate into current digital TV workflows and ecosystems, because most content is now distributed using these formats and protocols (codecs, DRM, etc.).
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