DVB-3DTV Standard Set to Boost 3D Market

The Digital Video Broadcasting Project (DVB), a consortium committed to designing technical standards for digital TV, has approved a 3D broadcast standard, DVB-3DTV which is now ready for implementation.

The final stage is to submit the DVB-3DTV to the European Telecommunications Standards Institute (ETSI) for formal standardisation. The DVB-3DTV specification is now available for downloading as Bluebook A154 ‘Frame Compatible Plano-Stereoscopic 3DTV from the new DVB website (www.dvb.org). Bluebook is the title given to documents that contain details of an open standard yet to be ratified by the ETSI.

Plano-Stereoscopic refers to systems that produce a left/right disparity at one fixed viewpoint. The left and right images are displayed on a fixed plane, in other words – the TV screen itself. It is how most 3D is displayed. The main implication for the requirement is that the left and right images must be arranged in a ‘spatial multiplex’ such that the resulting signal can be processed by the set top box substantially as a conventional HDTV signal.  Following ITU and other terminology, this is termed a Frame Compatible (FC) format and is how Sky 3D is broadcast.

There are different ways of arranging a frame compatible signal. One of which is the side by side approach where the left and right pictures are sub-sampled and anamorphically squashed in width. There is also the top and bottom approach where the images are sub-sampled vertically, anamorphically squashed in height, and placed one above the other. In different cases the side by side or top and bottom approach can deliver the higher picture quality depending on the HDTV format in use.

The DVB-3DTV specification aims to enable service providers to utilise their existing HDTV DVB infrastructures (Freeview, cable or satellite) to deliver 3DTV broadcasts to current 3D televisions.

The DVB-3DTV specification also attempts to provide solutions to the problem of subtitle and graphics positioning during 3D broadcast. The DVB-3DTV subtitling solution will use existing DVB subtitling implementations and will be backward compatible with 2D streams.

DVB-3DTV technical requirements highlights include …

• The resolution and other quality factors associated with the L and R images should be the same.
• The 3D TV specification shall provide a mechanism for broadcasters to signal a position for DVB subtitles within a stereoscopic view.
• The 3D TV Specification shall use where possible, existing DVB subtitling Specifications.
• The 3D TV specification shall allow 3D subtitles to the equivalent quality level as that of 2D subtitles
• The 3D TV Specification should provide a mechanism to guide a receiver to optimally position on screen graphics (EPG, Now/Next etc) within a stereoscopic view
• It should be possible to signal that a 3D version of a 2D service or event is being simulcast, and vice-versa, together with information on where the simulcast can be found

Metadata is included in the transmission to help the receiver identify that the broadcast is in 3D and to extract the two sets of images from the stream. This makes it easier to upgrade existing hardware to 3D with a simple software update.

DVB-3DTV Future Specification

This first phase of DVB-3DTV is only suited to current generation 3D but in the requirements document the system may include the broadcasting of depth maps to assist the viewer to adjust stereo window position and depth range for maximum individual eye comfort.

Whilst current 3DTV sets are Plano-Stereoscopic, there is current research into adjustable 3D depth  (a bit like the Nintendo 3DS depth slider), free-viewpoint 3D (where the viewer can view the 3D broadcast from different angles) and full HD 3DTV. Full HD 3D broadcasting might be a while off but if it does materialise (which undoubtedly it will ) it could possibly use the MVC (Multiple Video Codec) format which is the codex used in Blu-Ray 3D. This format is highly bandwidth intensive but there have been trials of broadcasting MVC content with another DVB standard – DVB-T2.

The DVB-3DTV standard can now be added to the list of other specifications including terrestrial HD standard, DVB-T2 and DVB-H, the mobile video standard supported by Nokia.

3D Focus asked DVB why they feel DVB-3DTV is needed when Sky have already implemented a 3D channel over existing DVB standard set top boxes. DVB responded by saying an open standard will help facilitate the market through interoperability and create economies of scale for the consumer.

What is the current state of affairs with terrestrial 3D broadcasting or DTT 3D?

Early this year, Mediaset became the first the commercial broadcaster to offer a 3DTV service on the DTT platform. The service, known as 3VOD, allows viewers to access 3D content which is locally stored on the hard drive of the viewer’s Motive Bestv set-top box. The content is transmitted in small quantities to the set-top box from a DTT multiplex during the day and night.

Spain became the first country to trial 3D content on the DTT platform in March 2010 during an event hosted by the consumer electronics association Asimelec in Seville. The trial used a terrestrial signal provided by the broadcast network operator Abertis and receivers from Gigaset, Panasonic, Samsung and Sony.

In the United Kingdom, the broadcast network operator Arqiva is trialling 3D services using the DVB-T2 network. The trial is taking place near London to a closed group of viewers. The trial offers HD content with the addition of further data for the 3D content.

In Italy, Sisvel is trialling 3D/DTT services in the Piedmont region. The trial uses the 3D tile format which integrates two 720p frames within a single 1080p frame and allows for display on both 3D and 2D HDTV receivers.

3D/DTT trials have also taken place in the Netherlands and Switzerland. In Switzerland, the trial offered the EU Commissioner Neelie Kroes the opportunity to view 3DTV services on the terrestrial platform.

3D Focus would like to thank Harold Bergin from DVB for his help with this article!