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EBU tests Ultra HD 4K

Another step on the way to Ultra HD (UHDTV) services has been taken by the EBU with the first shooting of test sequences in UHDTV 4K at 50fps. This follows successful testing of the Sony F65 workflow and equipment by the EBU Beyond HD group.

The testing is taking place at the Turin production center of Italian broadcaster RAI, supported by several EBU Members, as well as industry partners, including Sony, DVS, Astro Design, TV Logic, CW Sonderoptic and TPC.

Various genres of 4K test sequence were created to reflect a typical range of content types. This allowed EBU Members to fully test the immersive 4K format, and perform scientific assessments of the relevant equipment such as video codecs.

On one day, sequences featuring the actors from a well-known Italian children's television show were generated, evaluating movement as well as a wider field of depth. The following day last week, early morning outdoor shots were taken in the parks of Turin under the rising sun.

The sequences are being recorded in the F65 RAW format and transferred to the DVS Clipster for a first post-processing. Final post-processing will be handled by TPC in Zurich. Under test conditions, such sequences can be handled readily enough, but broadcasters and operators will be concerned over the impact for their networks of ultra HD video.

While impending 10GB Ethernet networks should be able to cope with the raw video, the widespread distribution of ultra HD 4K video would seize up current core networks, even if deep fiber technologies will provide sufficient bandwidth at the access level. This has stimulated activity around compression and bandwidth management, such as the recently started French project called 4EVER to develop a new end to end encoding scheme for future ultra HD services.

This involves a consortium of research laboratories including France Telecom’s Orange Labs, the Télécom ParisTech and INSA-IETR University labs, as well as transcoding vendor ATEME, state broadcaster France Télévisions, GlobeCast, TeamCast, Technicolor and Doremi. The objective is to apply the emerging High Efficiency Video Coding (HEVC) standard for encoding ultra HD, but also to go further by optimizing the whole end to end video transmission cycle from contribution to final consumption. The consortium reckons this will achieve further efficiency savings and bandwidth reductions beyond those possible through compression alone.

HEVC is the likely successor to H.264 under joint development by ISO/MPEG (Motion Picture Experts Group) and the ITU-T/ VCEG (Video Coding Experts Group). Currently available as a complete draft, it is due for final ratification as an international standard in January 2012, offering improved ability to trade between the key parameters of encoding complexity, compression rate, robustness against transmission errors, bandwidth, and video quality. It is designed to exploit the dramatic increases in computational power that have arrived since H.264 was conceived, so greater complexity is assumed, and it is expected to halve the bandwidth consumed by video at a given quality. This is roughly the same improvement that H.264/MPEG4 achieved over the preceding MPEG2 standard, sufficient to make the effort of development and deployment worthwhile.

This could be invaluable for 4K, which has four times the spatial resolution of 1080p, at 3840 x 2160, which is 8 mega pixels.

The 4EVER project is not just about bandwidth reduction, aiming also to improve the whole enhanced high-definition TV experience for viewers, even when consuming content on small devices that would not benefit directly from ultra HD. So initially a large part of the research effort will go into evaluation of the overall improvement in TV experience that can be provided not purely from higher spatial resolutions, but also higher frame rates, increased color depth, and surround sound.

For operators HEVC has the potential to increase capacity without having to upgrade their infrastructure. For example Video On Demand (VOD) output could be tripled, or three times as many IPTV channels could be delivered by a given processor.