“Huge success” for UHD-HLG test in Rome
December 14, 2015
Last week saw His Holiness Pope Francis perform the ceremony of the Holy Door, opening a normally bricked up portal to St Peter’s Basilica in Rome. The special event which starts an extraordinary ‘Jubilee of Mercy’ year for the Catholic Church was captured in Ultra-HD by the Vatican Television Centre (Centro Televisivo Vaticano) and with technical help from DBW Communications, Sony, satellite operator Eutelsat, facilities company Globecast and NTT Electronics. The images were sent around the world on Eutelsat satellites.
Importantly, the ceremony allowed the team to try some advanced experimentation with 4K/High Dynamic Range live images and in particular using technology developed by the BBC’s R&D division and Japan’s public broadcaster NHK in terms of Hybrid Log Gamma (HLG) signals.
HLG is widely considered to be the best method available of delivering high dynamic range images onto legacy high-definition TV sets. While these signals to ‘ordinary’ TV sets will not be Ultra-HD the technology means that the signals are fully backward compatible to existing displays and can be seamlessly carried via satellite, cable, IP and other distribution methods.
Perhaps just as importantly the technology is ‘royalty free’ and does not need licensing payments by either broadcasters or display equipment manufacturers. It has already been approved as the ARIB STD-B67, and the BBC says it is working with NHK of Japan to see the standard endorsed by the ITU and the Society of Motion Picture & Television Engineers (SMPTE).
Technically, the Rome trial used Sony 4K HDC-4300 cameras – equipped with three 2/3″ Sensors and capable of capturing native 4K and QFHD pictures – coupled to the BPU-4000 Processing Unit, in turn connected to external converter performing a remapping of the OETF (Opto Electrical Transfer Function) of the camera via a proprietary ‘beta’ software solution developed by SONY. The software allowed remapping the original signal coming from the cameras, to the Hybrid Log-Gamma (HLG) dynamic range OETF curve and to the Wide Colour Gamut (WCG) space of colours defined by Spec. ITU-BT.2020.
There are plenty of broadcasters who have wanted to start 4K/UHD transmissions but were being held back by what they feared was a lack of “Wow” factor. The industry has acknowledged that High Dynamic Range images helped deliver a large portion of that ‘Wow’ factor to 4K-equipped displays. However, the technology also needed a simple method of permitting getting the same signals to existing HDTV sets without introducing worrying extra artefacts.
HLG is described by the BBC as being an “elegant” solution to implement High Dynamic Range signals across networks and to devices.
Cristiano Benzi’s, director/Special Projects Italy for Eutelsat, and speaking exclusively to Advanced-Television.com following the Rome test, said that despite the rain the final images were superb. “It was challenging, but we were all very happy with the end result. Sony were key to the event, and with Vatican City TV and DBW there were a total of 19 UHD cameras in use, mostly F55s, and each using Sony’s baseband processing BPU 4000 units.
Technically, the UHD images produced were mixed through the OB vans of the Vatican Television Center and DBW Communications, were compressed in HEVC Main10-bit at 30 Mb/s on NTT Electronics HHC11000 encoders, and were then transmitted to Eutelsat’s 8WB satellite via the SNGs operated by Globecast at the Vatican. Received at the Eutelsat Rambouillet Teleport, the 4K UHD HDR HLG WCG pictures were inserted on DTH (direct to home) UHD channels “Eutelsat 4K1” on Eutelsat’s HOTBIRD 13E – also visible on the Italian platform TivuSat at channel number 200 – and on “FransatUHD” of the Fransat platform transmitted via EUTELSAT 5WA.
The 4K UHD HDR HLG WCG pictures from the Vatican were also transmitted to Africa, Central and Western Europe, MENA and Brazil via Eutelsat 8WB, to the Americas via Eutelsat 113WA, and finally to Asia and Oceania through Eutelsat 172A.
Benzi, added that 10 years time when the next ‘Holy Year’ is celebrated it could well be that Vatican TV would be covering the event in 8K. “It could be. The Japanese are fully backing 8K and testing in 2018 in readiness for their 2020 Olympics. Ten years from now perhaps 8K will be much more widespread. High-resolution panels are coming down dramatically in price, so 5 years from now and certainly 10 years from now it is quite likely that 8K panels will be inexpensive. Our industry has never stood still and tends to look forward to improved resolution.”