When HDTV came to market we had the benefit of a new generation codec (H.264) and improved modulation efficiencies thanks to DVB-S2 and DVB-T2, both of which make a notable contribution to the economics of delivery for the higher-definition content. With Ultra HD we will have to rely more on the codec efficiencies from H.265/HEVC.
There is a new satellite modulation specification, called DVB-S2X, which was approved by the DVB Steering Board in February and then sent to ETSI for standardization. This promises spectral efficiency gains of 20-50%, depending on the application, and the DVB is confident that it will be standardized in time to be implemented alongside HEVC in new decoders. But there is no work underway for any extension to DVB-T2 and no prospect of a DVB-T3.
Michel Chabrol, Director Marketing Innovation & Digital Cinema at Eutelsat, the satellite fleet operator that provides spectrum for DTH signals, does not believe any of this will damage the prospects for widespread UHD deployment. He believes the combination of DVB-S2 with HEVC will deliver enough efficiency for satellite platforms looking to launch UHD services. â€œDVB-S2 is good enough for the time-being,â€ he said recently on a Videonet webcast (The Ultra HD opportunity).
If satellite platforms can deploy UHD with the current modulation standards, what about DTT? Terrestrial TV is more bandwidth-constrained and there are national debates about whether mobile services should be given more prime spectrum at the expense of television. Will the combination of HEVC and DVB-T2 be enough for broadcasters?
Chabrol thinks broadcasters will find a way to launch UHD services, and if there is a spectrum problem we might see MPEG-4 AVC replace MPEG-2 or standard-definition TV eventually give way.
Focusing on France, he says: â€œThe feeling from the broadcasters in the French HD Forum is that the TV ecosystem needs DTT to be in good health and I think they are right. Many of them want to offer UHD on DTT as soon as possible and they are thinking about DVB-T2 and the implementation of HEVC.â€
However these services get to market, networks will have to cope with bit rates ranging from 10Mbps for VOD to around 25 Mbps for live sports for true UHD (as opposed to just 4K content, which increases resolution but without the higher frame rates and better colour depth).
The format also presents a challenge to telcos, who had to work hard to get HDTV to large parts of their subscriber base on DSL. Boris Felts, VP Product at Envivio, which is helping to pioneer HEVC encoding, says UHD it is also an opportunity for telcos to differentiate themselves by enabling the fast download of 4K files over broadband, for example.
He thinks UHD will encourage a technology transition that is already underway on telco networks. â€œIPTV operators are shifting their delivery from RTSP to HTTP for multiple reasons,â€ he explains. â€œOne of the reasons is the fact that capacity close to a DSLAM is different to what you can get at the end of the line, so they want technologies that can deliver variable bit rates and resolutions and UHD is one more reason for them to move down this path.â€
If you are interested in Ultra HD, you can listen to the recent Videonet webcast, â€˜The Ultra HD opportunityâ€™ free and on-demand by registering here. This one hour discussion features Michel Chabrol, Director Marketing Innovation & Digital Cinema at Eutelsat, Boris Felts, VP Product at Envivio, and Vassilis Seferidis, Director of European Business Development at Samsung looking at the market for UHD, the economics of UHD (with a detailed update on compression) and network capacity issues.