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Akamai reveals best bitrates for optimal viewing experience

6-8Mbps deemed optimal for connected TVs

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 and 6-8Mbps for an ‘optimal’ experience, 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 underwater shots, as viewed on different smartphones, set-top boxes, desktop PCs, tablets and smart TVs. Researchers used SSIMplus 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 HD TV.

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,” said Ian Munford, director of product marketing 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.

Munford added: “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.”