Using IP protocols and standards (i.e. Zixi, RIST or SRT) to transport professional-grade video for live sport broadcasts has gathered momentum. As a low-cost, high-quality option, broadcasters see IP as a revolutionary method of content delivery.
Nonetheless, transporting content over the internet brings technical challenges. Public internet services are patchy, and this can have a severe impact on the quality of feeds; packet loss, jitter and latency are well-known problems facing internet broadcasts. So, what can be done to ensure that live feeds are transported at a high quality?
What is RIST?
Transport protocols have been developed to help protect video content being sent from on-site to distribution centres via the internet. Similar to SRT, RIST is a way of delivering lossless broadcast-grade video quality over any type of internet infrastructure. RIST’s structure prevents disruption to services; it protects from packet loss and network outages, enabling broadcasters to retain the quality of their feeds.
Most of the organisations using it today are doing so over the public internet, for professional media workflows such as contribution, remote production, affiliate interconnect, primary distribution and cloud ingest. One of RIST’s strengths lies in its interoperability; with many different tools available to produce and package content, RIST ensures that equipment is compatible to send and receive content without any delays.
When would you use it?
A live sports feed is an example of why you would choose to use RIST. IP is highly competitive in terms of cost and therefore it is an attractive option when transporting live sports feeds. However, fans do not want a delayed feed; beyond the obvious annoyances at finding out that your team has scored in the group chat, customers interested in live betting and fan interactivity need the feed to be delivered with the lowest latency possible, without compromising on quality.
Prior to the availability of transport protocols, using IP for broadcasting introduced unacceptable levels of latency. Historically, satellite or terrestrial methods would have been used to help improve the reliability and consistency of transmission, however both methods come at a high cost. Protocols such as RIST remove the unpredictability of transporting content over the internet, ensuring that latency over IP, rivals that of traditional methods. Additionally, the RIST protocol delivers encryption to ensure that the valuable content is sent securely. The reliability and consistency of RIST introduces IP as a competitive and comprehensive method of distributing content.
Why would you choose RIST over alternatives?
We have found that RIST offers a higher bitrate than other methods, such as SRT. This is important when contributing live sports feeds because of the minimum bitrate requirements of 4:2:2 10 bit encoding profiles and opens it up to transport higher bitrate UHD feeds whether encoded as h.264 or h.265. This also makes it suitable for transporting Multi Program Transport Streams (MPTS) whether looking at traditional satellite multiplexes or a broadcaster packaging up their entire offering.
A significant benefit of RIST is that it has low technical debt. Built on top of multiple existing RFC standards, RIST is better positioned to benefit from decades of real world experience than any single vendor solution. Developing the protocol further, adding new features and functionality, especially around security, is not always possible when using protocols, such as SRT, as it is limited by the set of libraries at its core. RIST provides developers with a solid technical code base to build, enhance and deploy as future technologies are released, ensuring a continuing standards based approach to the transmission of live linear video over IP networks.
RIST is the first open specification and interoperable implementation that enables the use of Adaptive Repeat Request (ARQ) in multi-vendor scenarios. Using selective retransmission of lost packets through ARQ technology, RIST can recover information that is lost in transport between sender and receiver to keep latency both low and consistent over time.
The importance of reliable live IP delivery
Live sports feeds and IP delivery are clearly well-matched. IP’s flexibility, cost efficiency and versatility suit the rapid pace of sports broadcasting. By leveraging innovation within transport protocol development, and implementing consistent standards, the delivery of feeds over IP are resilient, consistent, and secure.
Choosing the right protocol for the job is key in maintaining the highest quality broadcast. By having an overview of certain limitations, broadcast engineers can ensure that feeds are not hindered unnecessarily. IP should, and will, help sports organisations and broadcasters to deliver more sophisticated, high-quality feeds to their customers. Ultimately ensuring that the customer has the best viewing experience possible on match day.