Although we had already heard a lot about UltraHD at IBC and IFA, we had the chance to hear Thomas Wrede of SES give a summary from his point of view at one of the SES seminars held during IBC, so we thought we’d go along.
First, Wrede talked about the importance of being closer to the display to be really immersed in UltraHD – as close as 1.5 times the height of the display. A key enabler for the broadcasters is the HEVC codec and Wrede said that broadcasters are looking at a budget of 25Mbps for each channel in UltraHD.
As we had heard elsewhere, the HEVC codec is not yet at the 50% level of efficiency for live encoding (which is essential for sport), although there is an expectation that this will be achieved in a couple of years as experience improves the encoders. Sky’s test with SES found that 25Mbps to 30Mbps is needed to really give good quality for live sports. However “slow” moving content can be streamed at bitrates as low as 8Mbps.
By next year, Wrede hopes that live sport will be able to get to around 20Mbps for sports, which should allow three channels to be transmitted on a single 33Mbps/36Mbps satellite transponder using statistical multiplexing. New equipment will be needed all through the encode and decode chain.
UHD Phase 1 will use the 2160p Main 10 profile with 50 or 60fps and 10 bit colour data. At the meeting it was confirmed that the technology is being adopted and standardised by ETSI and is at the “blue book” stage. Wrede said that Phase 2 will have “better pixels” and that Phase 2, with 8K and the features planned by NHK for Super Hi-vision will be “much beyond 2020”.
Early buyers of UHDTVs may be somewhat disappointed. Even some of those with HDMI 2.0 do not have HDCP2.2, so will not be able to show Hollywood content when it becomes available. HDCP2.2 is mandatory on STBs for UHDTV. Some 2013 UltraHD sets also do not support 50fps and even some 2014 sets don’t support DVB signalling properly. There is also a question of whether all HEVC encoders are compatible with all decoders. Later in his talk, Wrede said that SES had seen big differences in the image quality between different set makers.
Wrede talked about the Digitaleurope “UHDTV” logo which just covers interoperability between sets and the outside world. He said that he thinks that the logo is “a good thing” but it’s based on pragmatism rather than pushing the technology on. For example, TVs are allowed to support only 8 bit colour and audio is mandated only as stereo PCM.
Turning to Phase 2, the “better pixels” should deliver high dynamic range (HDR), wide colour gamut (WCG), high frame rates (HFR) and “better” audio. HDR is a technical battleground with proposals from Dolby, the BBC, Philips and Technicolor and standards bodies involved include the EBU, VQEG, MPEG and SMPTE.
Wrede made a call to the industry “We need standards now”. He also said there was also a need to understand what content really needs and benefits from HDR, which is less obvious in high ambient lighting.
Capture at High Frame Rate doesn’t seem to be a difficult challenge and improves the quality of the content. However, Wrede said that he had been surprised by how tricky the chip industry had found the move to 50fps with UltraHD, so he expects some delay as chip makers get up to the bandwidths needed.
Turning to audio, some kind of object coded audio (e.g. Dolby Atmos or the Fraunhofer technology) would be a big step forward for the home cinema business.
Wrede is looking for five milestones:
* Promote UltraHD beyond “more pixels”
* Get broadcasters to upgrade – a successor to HD-SDI is needed
* Real time encoders need to improve
* A standard for Phase 2 is needed
* The industry needs to start regular broadcasts. (Wrede said that his personal feeling is that this will happen in Q2 2015).
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In questions, Wrede said that Netflix seems to be encoding at around 13 to 14Mbps which may be a bit low. (BR)