RTVE presents a pioneering test of emission and reception in Ultra High Definition

At the RTVE Institute, the Corporation hosts the presentation of a 4K TDT signal pilot in DVB-T2, with HEVC coding) in which the UPM, Abertis, Sapec, Hispasat, Sony, LG, Panasonic and Samsung collaborate.

RTVE has organized a day at the RTVE Institute to publicize the pilot project launched to emit and receive DTT signals in Ultra High Definition (4K9) as well as the processes followed to achieve it. The test that was presented this Tuesday, June 24, has involved completing a chain of capture, editing and post-production, compression, transmission and reception.

The complete process has involved the recording of the documentary The Passion of the Prado in 4K. The signal has been compressed in HEVC at 50 frames per second, being broadcast in DVB-T2.

The Polytechnic University of Madrid, Abertis Telecom, Sapec, Hispasat, Sony, LG, Panasonic and Samsung have collaborated directly on this RTVE project.

Pere Vila, director of Technology, Innovation and Systems at RTVE, opened this day by stating that “after the 4K recording of the documentary The Passion of the Prado, the concern was the transmission of the signal in DVB-T2.” For this reason, TVE, in collaboration with the Polytechnic University, RTVE revived the old station that was used for high definition tests and with authorization from Industry, a 4K pilot signal has been put on the air. To do this, the coding provided by Sapec technology in HEVC 50p and a DVB-T2 transmitter provided by Abertis has been used.

According to Vila, "the idea would now be to be able to maintain, on a DVB-T2 multiplex, a signal being tested in Ultra High Definition, simultaneously testing new developments in high definition, mobility content and even radio."

Miguel Ángel Cristóbal, general director of Sapec, has highlighted that "as TV screens have grown, maintaining the pixel size gives the impression of loss of quality. The 'home cinema' concept is taking over." For the Sapec director, “resolution, colorimetry, presentation, greater dynamic range and audio improvement should be key in Ultra High Definition environments.”

Regarding the improvement in colorimetry, Cristóbal recalled that the color range in UHD is more than double that of HD. As far as the presentation is concerned, they were pleased that UHDV finally works with progressive scanning with the possibility of higher frame rates per second (120 fps), thus reducing the perception of movement and reducing flickering.

As far as dynamic range is concerned, Miguel Ángel Cristóbal has highlighted the tests that are being carried out around the world with High Dynamic Range to achieve a more realistic sensation. As for sound, "there is already talk of standardizing up to 22.2 audio channels with 16, 20 or 24 bits and sampling at 48 KHz and 96KHz. This would allow greater immersion in the contents, allowing their perception on the three axes," he assured.

Despite all the improvements, the main challenge now is, in the opinion of Miguel Ángel Cristóbal, to transport this signal and if possible with the current infrastructure, and there compression plays a fundamental role. The use of professional interfaces and storage (UHD1@50p would occupy 5.6 Teras or even 42 in 120p) are other issues that concern the sector today.

In broadcast, he has drawn attention to the development that HEVC coding is undergoing to adapt to new profiles (Main12, Main422-12, Main444-10, Main444-12), with higher levels in terms of the number of bits/pix and bit-rates. In addition, it increases the prediction angles to 33 compared to 9 for the H264. "In HEVC, it has been possible to optimize the image by even 50%, reducing bitrate while maintaining image quality. This allows us to put more programs in multiplexes and broadcast 4K in DVB-T2, DVB-S2 and even contributions in 4K," he highlighted.

Miguel Ángel Cristóbal concluded his speech by stating that "the challenges now are the implementation of all the tools in real time, overcoming the complexity in the development of decoders and encodings in HEVC with respect to H264, as well as the 'Range Extension' standardization for contribution applications. When is HEVC? From my personal point of view, much sooner than we assume."

Pilot broadcast in Ultra High Definition

Raúl Cortés, Key Account Manager at Abertis Telecom, has focused his intervention on the contribution, distribution and dissemination network with respect to the 4K challenge. Cortés has reviewed how in contribution we have gone from MPEG2 to MPEG4-H264 and now HEVC-H265, just as audio has evolved from MPEG1-LII to DD and DD+, in statistical rather than fixed multiplexing environments. In terms of interactivity, it has been migrated from MHP to more dynamic environments based on HBBTV. In distribution, from DVB-T and DVB-S it has evolved to DVB-T2 and DVB-S2... and "all this so that the user improves the quality, the number of channels and the interactivity. The change is only justified if what is coming is better than what is available today," he emphasized.

Cortés has also reflected on the relationships that standardization organizations, manufacturers, operators, production companies, the broadcaster and the audience themselves will maintain in the new Ultra High Definition environments.

José Manuel Menéndez, coordinator of the UPM Visual Telecommunications Application Group, has given a description of the DVB-T2 HEVC/ Ultra High Definition pilot carried out on UHF channel 56 (754 MHz with a bandwidth of 8 MHz, extended 32K FFT mode, 1/128 guard interval and a PRA of 125W) from the Technical School of Telecommunications Engineers. The transmission is carried out with a bit rate of approximately 37 Mbps.

The radiant system used in this pilot has four panels that distribute the signals from a workflow in which a computer intervenes where the 4K file is stored and, through an ASI gateway, a DVB-T2 modulator and an amplifier are attacked. The content is encoded in HEVC at 35 Mbps. The ASI gateway allows the modulator (an Egatel provided by Abertis) to be attacked through a DVB-ASI interface and the amplifier.

Menéndez has highlighted that one of the great advantages of DVB-T2 is that “it allows more configuration possibilities for all parameters, which gives it great flexibility to adapt to a variety of situations in mobile reception, UHDTV…” Furthermore, within the same multiplex, another advantage in his opinion of DVB-T2 is that it allows including different services even with different quality (Multiple Physical Layer Pipes).

Satellite

Jorge Rodríguez (Hispasat) has stated that satellites are currently the most used infrastructure for the transmission of high quality content. “It is to be expected that satellites will also be an important element in the take-off of Ultra High Definition,” he assured.

The Spanish satellite operator began carrying out its first 4K tests in 2013. Last year, coinciding with IBC, it announced its 4K pilot channel in order to promote the technology and facilitate the development of 4K among the different players in the market. At the last NAB the first permanent 4K service for North America was presented.

Last May, Hispasat already carried out the first HEVC transmission at 50 fps of a live event (a meeting between Portugal and Greece) in collaboration with the Portuguese Meo.

Given Hispasat's experience, to achieve a satisfactory Ultra High Definition broadcast a frame rate of 50/60p or higher (100-120 fps) would be necessary, a greater dynamic range to achieve better quality in low contrast conditions and a bit depth of at least 10 bit for large 4K screens.