SRT Open Source Streaming for Low Latency Video



4K UHD TVs now account for the majority of large screen sales worldwide. With 4K quickly becoming the new norm, broadcasters are facing increased pressure to differentiate and deliver engaging live content for UHD screens. In fact, when we polled broadcast professionals for our Broadcast IP Transformation Report about which technologies they thought would have the biggest impact on broadcasting in the next five years, 4K UHD ranked in second place, behind 5G.

With 4K comes increased bandwidth requirements which in turn can significantly increase the costs and complexity of traditional broadcast contribution workflows over satellite and dedicated fiber. The ability to reliably stream 4K video at very low latency over IP networks, especially over the internet, opens up the possibility for broadcasters to introduce live 4K services while lowering production costs.


Years ago, there were very few options available for delivering high-quality video signals for contribution applications over long distances, and all of them were expensive. Satellite connections had to be booked in advance and required relatively expensive terminal gear on both ends of the circuit. Terrestrial connections over dedicated video networks also required reservations, and are still only available in locations where carriers have chosen to deploy interfaces (known as PoPs or Points of Presence). Organizations using these technologies may have felt that they had few alternatives for transporting high-value contribution signals (including feeds from sporting events and live news), because the resulting programs needed to be of the highest quality for broadcasting to thousands or millions of viewers.

Today, many organizations have deployed devices that can transmit high-quality video feeds over the public internet, and this installed base is growing rapidly. These products provide a number of operational advantages for broadcasters, not the least of which is rapid deployment for breaking news stories. Being able to use whatever network connections are available at the site of a story permits live video signals to be transmitted when previously only taped reports could be filed. The flexibility of this technology also eliminates the need to send satellite or microwave equipment to remote broadcast locations, further reducing costs as well as improving flexibility and speeding up dispatch times.

Technologies that transport high-bandwidth, low-latency video streams over unmanaged networks must be able to handle large amounts of packet delay variation (jitter) and be able to recover packets that have been lost in transmission (packet loss). Both of these impairments can be accommodated through error correction or various applications of packet retransmission. Selecting the right implementation of these techniques and providing a product that minimizes delay and maximizes video quality is the key to a successful solution.

A number of companies have developed closed, proprietary systems to address the vibrant market for delivering contribution-quality video over the public internet. Several of these offerings require ongoing monthly payments in exchange for a fixed number of hours of use. Unfortunately, these single-vendor solutions do not allow streams to be sent to or received from other manufacturers’ devices. This prevents end-users from exchanging content with other users who don’t own the same brand of equipment. Proprietary solutions are also at risk of becoming orphan products, when vendors go out of business or discontinue product lines, as has happened more than once in the recent past.