Content delivery platform specialist Akamai has released initial findings from research into the requirements for optimal viewing experiences across a range of devices.
The research, conducted in association with Eurofins, provides guidance into what is an optimal video stream across a range of different content genres, devices and network conditions. Findings show that delivering complex content such as sport or high action onto a large-screen TV requires a minimum of 6Mbps to achieve an ‘excellent’ viewer rating, whilst smartphones require between 2-3Mbps. For less-complex content, optimal bit rates are lower and 2-4Mbps will still deliver an excellent visual rating on large-screen TVs.
The study looked at different types of content, ranging from basic talking-head footage to complex under-water shots, as viewed on different smartphones, set-top boxes, desktop PCs, tablets and smart TVs. Researchers used SSIMplus – an objective full-reference perceptual video quality-of-experience (QoE) index – in order to rank the perceived quality of the video, where anything rating above 80 out of 100 is deemed ‘excellent’- or the equivalent of HDTV. 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.
“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 Ian Munford, Director of Product Marketing in EMEA for Akamai. “By managing the strategic relationship between content, delivery and devices, it’s possible to improve the quality of experience and reduce buffering significantly.”
The study, showed that optimal stream rates outlined in the study can be achieved across most mature markets to a high percentage of the population.
“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,” continued Munford. “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.”