15 November 2012 In partnership with satellite operator SES, Sony transmitted live 4K video via satellite at this years IBC show in Amsterdam. Neal Romanek looks at the viability of the delivery method
The Sony/SES demonstration, 4K video was uplinked from the SES headquarters in Luxembourg via the Astra satellite system.It was encoded in the H.264 standard at a bitrate of 50 Mbit/s and the content played out at the SES and Sony booths on 84-inch 4K displays at a resolution of 3840 x 2160.Nobody doubted it could be done it wasnt the broadcast equivalent of the moon landing - but it put to the fore the question: how close is the industry to wide satellite distribution of higher-resolution content, be it Sonys favoured 4K, NHKs Super Hi-Vision, or other formats waiting in the wings?
Sony Europe head of technology planning Mark Londero was responsible for putting together the IBC demo. What we were aiming for was a proof of concept to show its possible to carry 4K using AVC, or H.264, encoding, which is the current mechanism for carrying HD in Europe. We demonstrated its possible, although we recognise that at that bitrate, using AVC, it may not be commercially so attractive because the bitrate is very high.
Building the kit
The only hurdle facing the Sony demo was finding an AVC/H.264 decoder that operated at a high enough bitrate. To decode 4K, a level 5.2 decoder (capable of a maximum decoding speed of 530,841,600 luma samples) was required, and although there are computer graphics cards capable of decoding at that level, there were no commercially available decoders appropriate for a 4K TV demo, so Sony built its own prototype. Londero sees the future transmission of 4K as a commercial rather than a technical matter. At present, given the bitrate, 4K transmission would mean taking up one satellite transponder almost entirely. However, next year, HEVC (High Efficiency Video Coding), also known as H.265, is expected to be ratified (see box). Potentially, that new codec offers the promise of halving the bitrate requirement for carrying 4K, and then it becomes very interesting, says Londero.
Some view NHKs 8K Super Hi-Vision, along with 3D formats, as competition for 4K broadcast, but Londero believes 4K will end up being the higher-resolution choice for consumers. Of course, Sony has put itself squarely behind 4K development, both in its cinematic distribution and future home displays, but beyond the commercial interest, Londero sees 4K as the most practical option. He says resolutions beyond 8K will simply be gilding the lily for most consumers.
SES says that since 4K screens are also not widely available, it is not expected that 4K (ultra-high-definition) transmissions will be delivered to the home until after 2014. SES vice-president of reception systems Thomas Wrede also acknowledges that there are bandwidth constraints that need to be overcome. To Wrede, the greatest success of the Sony demo was stimulating discussion and encouraging the industry to look ahead.
There is a similar development here to HDTV and to 3D, Wrede says. You need certain things to happen and to be ready at the right time. Of course, offering something to customers that is going to fully take over a transponder is not appealing, so we will need to look into means of reducing the data rate requirement.
Fortunately, the Digital Video Broadcasting Project (DVB) is working on improvements in efficiency of the modulation and coding technology, the MPEG group is working on HEVC and there are discussions about a variant of HEVC as well. I think with HEVC we can bring data rates for 4K television down to 20 Mbit/s or less.
David Furstenberg, co-chairman of satellite optimisation company NovelSat, sees the transition to higher-resolution formats as inevitable and believes that, as with past innovations, sport will drive the change. Sport is always at the avant-garde end of the industry. People want to see every detail of the game and every move of the players on the field, and this will drive us toward larger and larger screens and to higher resolutions, he says. HD is great only up to a 60-inch screen, and remember, broadcast today is also 1080i, not 1080p its not the full HD, its half of it. As we go to larger screens, and things are expected to become larger than life, HD whether 1080i or 1080p will no longer be adequate.
Furstenberg agrees the issue of bandwidth might force difficult choices, but says that technologically, 4K satellite transmission is ready to go. The increase in bandwidth for 4K is very dramatic, but I dont see any hurdles in the way of progress. I think 3D is much more questionable. The issue with 3D is that we are toying with the brain and some people still cant watch it comfortably, but for those new higher-resolution technologies, there is no such obstacle. I believe 4K and 8K will happen, for sure, and when it does, it will be carried by satellite.
There are two challenges to satellite transmission of higher-resolution formats, Furstenberg says. The Sony/SES demo at IBC focused on the professional side of the business, on transmission. You need to be able to transmit all over the world and the only technology today that can support this type of broadcast is the satellite industry. We can even support, from the transmission side, 8K with a 72MHz transponder, something that no other technology can do.
The second challenge is the direct-to-home aspect. Currently, set-top boxes do not have the capability for this type of video stream. These new displays will require a much more efficient technology, but it will happen.
SatLink Communications chief executive David Hochner is more cautious. Until the bandwidth issues are resolved, he says, higher-resolution broadcast will work better with local origination carried by fibre via the domestic infrastructure within each market.
