The BBC has begun a trial to establish how well its approach to low latency streaming performs in viewers’ homes.
Over the next few weeks, viewers on selected devices that have opted into iPlayer’s ‘beta’ mode may see an experimental low latency stream of BBC Two when watching live on iPlayer.
In a blog post Lead R&D engineer Chris Poole explained that while the delay on TV streamed over the internet had been significantly reduced, it was still around 40 seconds behind a traditional broadcast.
“For some content, viewers may not notice, but for live sport and for live events with a social media following, delays can detract from the viewing experience. We are aiming to address these delays whilst maintaining a high quality of experience through our work on ‘low latency streaming’,” he said.
Latency is a problem that commercial and public services continue to grapple with. On the BBC’s broadcast services the end to end delay is just 8-10 seconds
The BBC is using a technology called Low Latency DASH with chunked CMAF segments. It will then use performance data from the BBC Two sessions to get a detailed understanding of how the quality and reliability compares with our traditional live streaming in a wide range of ‘real’ homes.
Poole says there is a debate as to what should happen if users do experience some rebuffering. “Should the stream just resume, leaving them further behind for the rest of the programme? Should the stream catch up, skipping a few seconds in the process?” The BBC has chosen to allow the trial steam to play slightly faster after a stall, aiming to maintain low latency but without the viewer missing any of the action.
As the functionality is not available everywhere, the BBC is starting the trial only on those devices that support this variable speed playback capability. The first device models to be added are 3rd generation Amazon FireTV Stick, 2nd generation Amazon FireTV Stick 4K, and Samsung CU8000 and CU8500 TVs.
The trial is restricted only to England and Scotland and will run between 9am to 5pm daily.
