With streaming never more popular thanks to the World Cup, CDN and cloud delivery platform provider Akamai has released initial findings from research into the requirements for optimal viewing experiences across a range of devices.
Researchers used SSIMplus in order to rank the perceived quality of the video, where anything rating above 80 out of 100 was deemed ‘excellent’- or the equivalent of a HDTV experience. Across device types, the bitrate required to achieve an ‘excellent’ score varied considerably. When examining the relationship between delivery, player technology and content, Akamai also found that consistency of throughput was a key element to improving KPIs such as stream buffering.
Akamai’s findings show that delivering complex content such as sport or high action onto a large-screen TV requires a minimum of 6 Mbps to achieve an ‘excellent’ viewer rating, whilst smartphones require between 2-3 Mbps. For less-complex content, Akamai found that optimal bit rates are lower and 2-4 Mbps will still deliver an excellent visual rating on large-screen TVs.
“Due to the variable nature of player technology across such a wide and diverse device landscape, the ability to deliver a stream with consistent throughput, at any bitrate, is critical to ensuring the highest quality viewing experience,” explained Akamai EMEA director of product marketing Ian Munford.
“By managing the strategic relationship between content, delivery and devices, it’s possible to improve the quality of experience and reduce buffering significantly. As the OTT market matures, quality of experience metrics need to evolve to include visual quality as well as the typical KPIs such as stream buffering and start-up time. This research shines a light on the role of perceptual quality and we hope to help broadcasters better understand ‘what good looks like’ as well as highlighting savings that they could realise by eliminating bitrate profiles that could be unnecessary.”
What has made the issue of QOE even more relevant have been the extra strain put on networks delivering streaming services, in particular due to the World Cup in Russia. Indeed, failure to cope with demand saw Optus in Australia abandon its online video offering while the BBC had to issue a warning of likely delays in feeds for those wanted to watch football games online.