UHDTV can bring benefits to TV on smaller screens by reducing motion blur, even though viewers may see little difference from higher resolutions, according to Andrew Cotton, principal technologist within BBC R&D’s broadcast and connected systems section.
In a recent blog posting, Cotton indicated that the BBC’s current thinking was that the UHD-1 format – with resolution of 3840×2160 pixels – is better suited to smaller screens than the UHD-2 format, with a resolution of 7680×4320 pixels. However, the current 1920×1080 HD format is “sufficient for the vast majority of viewers with screens of up to around a 60-inch diagonal” and the main benefit of UHDTV could be from the higher frame rate – 100 frames per second rather than the current 50fps – he said.
“For us and many in our industry, UHDTV is about a range of improvements that together will deliver a much more lifelike experience in the home,” said Cotton.
Referring to a workshop conducted in London in May by the EBU and DVB, Cotton said that the BBC had used this to demonstrate the benefits of ‘short-shuttered’ 100fps and 150fps video. “The improvements are dramatic,” said Cotton. “They come close to the 300fps we were recommending back in 2008, and although still technically challenging, are considerably easier to deploy. We don’t yet know the exact figure that’ll be needed, but we believe higher frame rates should certainly be part of any UHDTV broadcasting standard.”
Cotton said that the current ITU recommendation fo 120fps as the basis of a global standard could cause format conversion problems for European 50Hz-based broadcasters, with UHD material being subject to ‘judder’ effects if used in standard HDTV programming. He said there was now a “growing consensus” that 50Hz broadcasters needed to use frame rates based on multiples of 50fps.
Cotton said that the BBC demo also highlighted the benefits of 10-bit HEVC rather than 8-bit systems current today.