Wimbledon goes 3D

The Mens’ and Ladies’ Finals of this year’s Wimbledon Championships will be the UK’s first free to air 3D television broadcasts.

The BBC has announced that live 3D coverage of the finals will be provided on Saturday 2nd and Sunday 3rd July, on all the digital TV platforms that carry the BBC HD services. The finals will be broadcast in standard definition on BBC One, in high definition on BBC One HD, and in 3D on the BBC HD channel.

There will also be live 3D screenings in some cinemas around the UK, and I daresay a lot of shopping centres will be getting in extra sets of specs, in the hope of shifting plenty of kit on the day.

The BBC press release puts this firmly in the “editorial experiment” category, so it’s premature to expect any regular service at the moment; this is a test, and also a way to mark the 125th anniversary of the Championships as well.

How it works

The release is a bit short on the technical detail, about which I’ll see if I can find more information (Update: ‘side by side’ format is confirmed; see below). But since no special receivers are required, then my gut feeling is that they’ll be using the ‘side by side’ format to broadcast.

In ‘side by side’ 3D, a single frame actually has two images encoded in it, one for the left and one for the right eye. So it looks a bit weird to an ordinary receiver, but you can still make sense of it, as it’s just a picture, albeit with each half almost the same. A 3D TV, however, will spot the format and zoom each half to full screen, and ensure the left image goes to the left eye and the right image to the right eye, via whatever 3D screen technology it actually uses. The downside is that horizontally, instead of 1920 (or 1440) pixels, since there are two images, each eye only receives half that resolution.

It’s possible to broadcast in other ways, but unlikely, I think.

For example, ‘frame sequential’ 3D requires sending a full HD frame for the left eye, and then one for the right eye. This is Panasonic’s preferred format, because each frame is full HD resolution, but of course that means a lot more bandwidth; you at least have to double the frame rate as you need twice as many images. I suspect, at rates that a receiver understands, this wouldn’t actually break most 2D sets, but you’d get a nasty flickering. It’s really best suited to delivery systems like Blu-Ray.

And, since Freeview HD can only go up to 25p as a frame rate, it’s not possible to use frame sequential, on that platform anyway – you’d effectively be getting only 12.5 frames per second. And I think it’s unlikely the BBC will be using different 3D formats for different platforms, too.

The other way of sending 3D, ‘2D plus depth’ is, unless I’m a bit behind, not an entirely finished standard; it involves sending information about the details for one eye, plus that needed to make the image for the other. Ultimately, some variation of this may be used to create a ‘service compatible’ standard, which is one where someone with a 2D set can tune in and see a decent 2D picture, while a person with a 3D one will see the extra dimension – which will avoid the need to have a separate broadcast stream, as the BBC are doing this year.

So, based on what I know now, I’d say it’s most likely going to be a side by side broadcast; I’ll try to check this when I can, though there wasn’t time between reading the release and the end of the embargo.

Definitely a worthy experiment, I think, and it’ll be interesting to see what people make of it. And how many people moan that three channels were taken up with the same programme.

Update: This BBC blog post confirms that they will indeed be using the side by side format, and increasing the resolution of the stream to the full 1920 pixels.

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