3D TV on Freeview in time for the Olympics? Not as implausible as it sounds

The BBC wants to film the 2012 Olympics in 3D -- thrilling news for sport fans, no doubt, but to do that, it would need to support all the platforms its TV is shown on, not just Sky and Virgin. Freeview offers the most challenges, but transmitter and broadcast company Arqiva is working on ways to send 3D over Freeview without disrupting existing channels.

For the BBC to adopt 3D would first require it gets approval from the BBC Trust. To do that, the corporation needs to provide a solution for Freeview to satisfy the BBC's regularity requirement not to favour a single platform. And let's not forget, most digital TV viewing in the UK happens via Freeview, so ignoring it is a bad idea.

Sky, whose 3D channel is currently showing in pubs but should launch fully this autumn, sends its 3D signal using a method called side-by-side. 3D information is sent in two, reduced-size frames -- 3D HD isn't 1080i like Sky's regular HD, it's closer to 720p -- placed side by side on screen. A 3D-capable TV then takes these two images, and produces a full-screen 3D picture from them. Any system used on Freeview, however, would have to be more efficient to make better use of the bandwidth available. Setting up new channels isn't really practical, so a different approach is needed.

The solution is to ape the way in which Blu-ray movies are encoded to include 3D information. Essentially, the HD movie is placed on to the Blu-ray disc, as usual, with some information about the three-dimensional depth added on top. This allows non-3D players to play the film in 2D, and saves space by not requiring two versions of the film, nor two full frames for both the left and right eye. In 3D broadcasts using this system, standard set-top boxes would see the 2D video, and ignore the 3D difference information. 3D-enabled boxes, though, would use the extra info to reconstruct a 3D image.

The process, known as 2D+delta, uses something built into MPEG video called Multiview Video Coding (MVC). The difference information, which gives spatial depth, is sent as a data stream along with the normal 2D video. It's fairly efficient, requiring between 30 to 60 per cent more bandwidth than a standard video stream. And while that's significantly more data for Freeview to cope with, it's certainly plausible, at least in theory.

Do we need or want it 3D TV on Freeview though? More importantly, how will we manage without the plethora of shopping channels that would need to be booted off the platform to make space for it? Ultimately, if consumers buy 3D TVs, it's highly likely we'll see 3D on Freeview at some point. If everyone stays away, perhaps we'll get more lovely HD channels instead. Tell us what you think of 3D on Freeview in the comments below, or on our Facebook wall.