SMPTE focuses on emerging technologies at Torino Rai Production Center
The Torino Rai Production Center was the venue for the recent ninth seminar organised by the Italian section of SMPTE and focusing on emerging technologies. The primary topics discussed during the day were 4K and broadcast market transition from SDI production infrastructure to IP-based set-ups. The new generation of audio and video codecs was also integral to these seminars.
The first speech by Alberto Morello of RAI Research Centre and Innovation Technology (CRIT) perfectly framed the view of Italian public broadcasters, namely: the broadcasting of television signals in Italy is today mainly based on digital terrestrial transmission and “[getting] a multiplex to transmit in 4K is like getting back to PAL’s time”, according to Morello. In his view, the true quality leap for the viewer could be the combination of HDR (High Dynamic Range) with HD resolution images that would not overwhelm the transmission infrastructure. It is only a pity that, as Morello pointed out, the HDR standard for live broadcasting, HLG (Hybrid Log Gamma) developed jointly by BBC and NHK, does not support HD Rec.709 colour space of HD TV sets available now, and is therefore compatible only with the new generation UHD TV models, which support the Rec.2020 colour space.
Morello then referred to problems pertaining to the use of HEVC codecs related to the patents held by the various companies that participated in its development – a topic that was subsequently pursued by the Sisvel representative, Alessandra Mosca.
Giorgio Dimino, the other representative from Rai CRIT, went onto detail the standards for UHD. He highlighted the main differences between the two HDR image management methods provided by BT.2100 – Perceptual Quantization (PQ) and Hybrid Log Gamma (HLG) standards. The first was originally proposed by Dolby for the cinematic environment and requires difficult colour correction interventions to handle live broadcasts.
On the contrary the HGG guarantees a certain level of retro compatibility with non-HDR TVs. As per colour spaces, Dimino believes that the impact of the Wide Color Gamut (WCG) based on the Rec.2020 is not that attractive for the viewer since Rec.709 – which is already widely used for HD – covers natural colours sufficiently well, and it is only with synthetic images that it is possible to appreciate the greater extension opportunities.
The BT.2100 will then be able to transmit High Frame Rate (HFR) video up to 100/120 Hz, a value that would allow for better clarity when it comes to moving subjects.
However, in this case the problem is that today there are no TVs on the market capable of playing HFR videos. Iu order to assure retro-compatibility with 50 Hz TV sets, Dimino suggested a strategy of transmitting HFR video with different odd and odd frame identifiers so that the TV can distinguish and reproduce only the necessary ones. Unfortunately, the result is to get a certain ‘clicking’ of the images.
Even at the front end of production, there are still several issues to be resolved in order to adapt the SDI standard family to HDR and WCG support, and it will take at least a year before the situation is defined. “At present, HDR video on SDI is handled manually; HDR productions are somehow [a matter of more extensive] craftsmanship,” said Dimino.
Non-linear and interactive
Mediaset’s representatives, Marco Gorni and Stefano Braghieri, then described the latest developments in nonlinear TV and interactive services. Gorni described the process of developing a new Mediaset service, while Braghieri traced the history of the standards for interactive TV. The only problem for Italy is that the mhp sets installation base is estimated at over six million with a replacement forecast of three or four years. So the two standards are intended to coexist for a while and who develops interactive services will have to take this into account.
Enzo Paradisi of Sky Italia highlighted the advantages of the transition from SDI to IP, quoting the added value in terms of IP flexibility, which is now tangible only for some specific applications such as the creation of a new thematic channel. This is achievable within a few hours. It could also be very useful in the case of the creation of a disaster recovery structure for which a single backup centre can handle multiple production centres with obvious economic benefits.
John Ive, director Strategic Insight of the International Association for Broadcast & Media Technology Suppliers, presented several world market researches that outline the broadcasters’ strategies for the coming years. There is growing interest in the use of IP technologies, albeit due to the need to put more security on their computer networks against attacks from hackers. Over 50% of respondents consider the possibility of transmitting immersive video (VR) but are not sure that they can benefit from it. As far as UHD is concerned, 10% declared they have already launched, but only another 22% plan to start transmitting UHD video in the next two or three years. Hence there is a considerable degree of uncertainty about what infrastructure to adopt.
State of standards
The state of the IPMP work on IP standards was illustrated by Alfredo Bartelletti, president of the Italian section at SMPTE, who discussed the organisation’s work on IP. The ST2110 standard is now coming to the point of adoption with several manufacturers introducing devices that will support it, as seen at the recent NAB Show, but it will take a few more years for all the necessary parts to be put in place.
Angelo D’Alessio then focused on the Quality of Experience (QoE) or how to establish the optimal level of visual and auditory quality, taking into account not only objective factors that can be determined instrumentally, but also social and psychological factors relating to the audience – for example, the enjoyment of multimedia content.
Alessandra Mosca from Sisvel described the current situation and the state of progress of the development of new video codecs, both from a performance point of view and a legal perspective. In short, the HEVC codec is currently the best possible choice in terms of quality, but it is necessary to deal with patent issues. In fact, two patents owned by two associations are under consideration now, a third one has just added, and some other companies have so far not yet requested anything for their patents.
The HEVC codec will have a Future Video Codec (FVC) successor, still in embryonic development phase by the Joint Video Exploration Team (JVET), which was founded by the union between the ITU and MPEG workgroups. If everything goes according to plan, the FVC codec will be standardised in 2020.
The royalty-free alternative developed by Google today is comprised of the VP9 codec that is mainly used for video distribution but is not widely considered to achieve the comparable visual quality of the HEVC at the same bit-rate. Overcoming this limit is the goal that the Alliance for Open Media has placed with the AOMedia Video 1 (AV1) codec, based on the VP9 evolution.
The AV1 codec should see light within the year: the first results are promising, though in terms of efficiency improvements over the WHO are not that significant. The advantage of the royalty-free AV1 codec remains valid, but the representative of Sisvel – a company that deals with patent licensing management – has voiced some doubts about it.