The BBC has unveiled technology that could eliminate the delay on internet live streams of big sporting events, an issue that affected millions of viewers during the World Cup in the summer.
The industry-wide problem was starkest during England’s run to the semi-final. As millions watched online, a time delay of 20 seconds or longer meant many viewers learned about goals from alerts on their phone or the screams of their neighbours. By comparison, TV coverage broadcast via Freeview takes only about five seconds to reach the home.
The BBC’s research and development team has now developed a prototype that could bring the delay in line with traditional TV broadcasts. Chris Poole, the lead research engineer at the corporation, said: “There are many factors that contribute to the delay, or latency, that you experience when watching a live stream over the internet.
“Some of this latency helps give you a reliable stream that will play without interruption, despite competing with other traffic on the network. But there are also other causes of delay that we can reduce.”
The innovation will be on display, along with other BBC development projects, at the international broadcasting convention in Amsterdam this week. The live-stream technology is not ready to be rolled out to the public as any final format is likely to require industry-wide collaboration to establish a standardised system.
Live streams are split into segments of video of about four to eight seconds. These are encoded and then passed to internet content distribution networks. A viewer’s device, such as their laptop or mobile phone, must then request and decode each segment. The device will tend to download several of these as a buffer to ensure a smooth viewing experience.
The end result can be a delay that is several times the length of a segment. While this may not be a big problem when watching a film or documentary, it can create an unsatisfactory viewing experience during a live news or sports event.
Poole said improvements in fast internet connections meant many British viewers no longer needed to allow video to buffer before it was played. “For many users with a good broadband connection, the media buffer used by players to ensure reliable playback is larger than needed, which introduces unnecessary delay,” he said.
“We’ve been investigating how we can reduce the delay for viewers whose internet connection allows it, while introducing appropriate delay for those who need it for reliability.”
The development follows a surge in demand from people wanting to watch live events on their mobiles or laptops. The massive shift to online streaming of sports, with the likes of Amazon buying exclusive rights to some Premier League football matches, means the issue will become even more acute.
