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3DTV: From Stadium to Living Room A ustralia’s Channel Nine and SBS (Special Broadcasting Service) are collaborating to broadcast live, in high-definition 3D, the three State of Origin rugby league matches (produced by Nine) and 15 World Cup soccer games (produced by FIFA) between May 26 and July 12 this year. This has been timed to coincide with the recent Australian consumer launch of 3D-capable high-definition television sets. These broadcasts are possible due to a two month experimental broadcast license covering transmitters in Sydney (Gore Hill), Melbourne (Mt Dandenong), Brisbane (Mt Coot-Tha), Adelaide (Mt Lofty), Perth (Bickley), Newcastle 18  Silicon Chip (Cooks Hill & Charlestown) and Wollongong (Knights Hill). These broadcasts are made on a variety of channels but in all cases the trial is available on digital channel 40. Some areas will unfortunately be left out due to the limited number and range of the transmitters being used for the trial. One of the purposes of the trial is to assess consumer interest when major live sports events are made available. Making such broadcasts involves new technology virtually every step along the way – from the cameras at the game, to the processing and broadcasting equipment at Channel Nine’s headquarters and ending with the reception and display of 3DTV in viewers’ homes. siliconchip.com.au On Wednesday, 19th May 2010, Nine Network Australia and SBS Corporation began the first free-to-air 3D television broadcast in the world. We take a look at the technology involved in getting 3DTV live from the sports field to your home. To assist with these new challenges at the production end, a technical team was brought in from California. The Burbank-based company “3ality” (pronounced “threeality”) have provided 3DTV production equipment and a great deal of expertise, putting the Channel Nine team on a crash-course in 3D television recording and production. 3D cameras We have already covered 3D camera technology extensively in “3D TV Is Here At Last!” (April 2010) and “Breakthrough Aussie Innovation: Making 3D Movies” (June 2010). 3D cameras for TV broadcasting are similar siliconchip.com.au by Nicholas Vinen in concept to those used in shooting movies. The only real difference is in the image resolution – movies are shown on larger screens and demand more pixels, even compared with Full HD (1920x1080 at 50/60Hz, known as 1080p). However, for the State of Origin rugby league match on the May 26, one innovative camera made its appearance: a wireless, hand-held, broadcast quality 3D rig and there are only a handful in existence. It consists of a pair of “lipstick” cameras mounted side-by-side to simulate the interocular distance and gives viewers the impression that they are standing on the sidelines, either looking at the match itself or else at the players on the bench. July 2010  19 Nine NRL SOO1 On-Air Production Gallery, taken at the first State-Of-Origin match held in Sydney on May 26. Each of the monitors depicts the live individual camera output, with the Director “calling the shots” as required. Because the experience of watching 3D sport is so different from what we are used to, the camera work is tailored to suit the experience. The 3ality team have trained the camera crews in new techniques optimised for 3D sport coverage. Viewers watching the games in 3D will notice fewer cuts and zooms than we are used to on regular TV. There are also fewer close-ups. This is because with 3D TV, it is much easier to follow the action with a wider perspective. The players and the ball are very well defined on the screen and since our brains are already wired to decode depth information, following the action is intuitive. As a result, wider, longer shots tend to be used which are better able to show the action within a larger context. In fact, watching sport on 3DTV is much more akin to being at the game than is a regular TV broadcast. However, this isn’t the only reason for changing the shooting technique. The other reason is that rapid cuts and zooms can be very jarring when viewed in 3D, especially if the convergence distance changes dramatically between shots. Therefore, every 3D camera has an additional operator whose sole job is to control the convergence distance for that camera. This is managed by a new production position, a “stereographer”, who is in charge of ensuring that cuts between cameras are only made at the point when their convergence is close enough to avoid a jarring transition. Camera convergence can be adjusted mechanically but 20  Silicon Chip 3ality’s system also involves digital processing for finer control. It is even possible to adjust convergence with digital processing only (eg, with a Sony MPE-200 Stereo Processor) but a combined approach is best. 3ality have developed rigs using two different mechanical systems. One solution is to mount the cameras side-by-side with one fixed and the other moving closer to or further from it (while automatically adjusting zoom and focus). The other method involves beam-splitting using a piece of precision semi-mirrored glass similar to that used in telescopes. In this case the right camera is mounted horizontally and the left camera vertically. Beam-splitting rigs can simulate much smaller interocular distances (virtually down to zero) so they work much better in scenes with objects close to the camera. 3D encoding and transmission Once the cameras have captured the action and the production team have chosen which shots to use for broadcast, the next step is to add overlay information such as the time and score. This too is accomplished digitally and depth information is added at the same time which makes the scoreboard appear to float in front of the sports field. The next task is to encode the final left/right video streams into a format which can be transmitted over the air and received by home 3DTV sets. siliconchip.com.au This photo shows both types of cameras from 3ality with the OB (Outside Broadcast) van in the background. The side-byside rig is front while the horizontal/vertical beam-splitting rig is behind it. There are a number of ways to do this but there is currently no standard approach. Most systems involve combining the left and right eye images into a single video stream which is transmitted similarly to regular HD programming. A 3DTV set extracts the left and right images and displays them separately to viewers’ eyes to reconstruct the 3D image. Channel Nine and SBS are using the side-by-side method which involves compressing the images horizontally so that they are each half the normal width (an “anamorphic” format, ie, not retaining the original aspect ratio) and then placing the left and right eye images on each side of the virtual screen. With this method, the decoded images have half the normal horizontal resolution (ie, 960 pixels rather than 1920) but this is not readily apparent when watching it. This format gives the best results when using the industry standard 1920x1080i HD format. Other similar schemes for combining the two video streams into one include above-and-below, line interleaving, checker-boarding and so on. However, the side-by-side approach means that viewing the 3D stream on a normal 2D set is not impossible – it looks very odd but it is possible to make out what is going on. Ultimately, 3DTV signals may end up being transmitted as standard HD video for the left eye along with some invisible sideband data which contains the depth information. This system is known as 2D plus Delta or 2D plus Depth. siliconchip.com.au The 3DTV set will then use this information to reconstruct the right eye image. The advantage of this approach is to yield a single backward-compatible transmission suitable for display on a normal 2D HDTV set, as well as a 3D set, without needing a full additional broadcast channel. As standards are still in development, 3D TV sets do not currently support this method. However all 3D sets now being sold (as far as we know) have a USB socket which is intended to allow new firmware to be uploaded to the TV. This means that if and when a sideband 3D system like this is standardised, manufacturers might release patches enabling their sets to decode this type of signal. As a result, you can buy a 3D set now without too much risk of it becoming obsolete as the broadcast methods change. MPEG-4 Readers may recall that in “Digital TV – Where To From Here?” (March 2010), Alan Hughes argues that HDTV broadcasts should move towards MPEG-4 encoding. Well, Channel Nine and SBS have made a significant step in this direction with their decision to exclusively use MPEG-4 for 3DTV broadcasts. This decision was based on a number of visual quality tests between MPEG-2 and MPEG-4 encoded transmissions, with the conclusion being that 14 megabits/second MPEG-4 July 2010  21 Here is what you will see if you tune into the trial broadcast with an MPEG-4 capable 2D HDTV set – the anamorphic left and right eye images side-by-side. Note how the perspective differs, for example, you can see different sections of the advertisment behind the players in each image. The white objects on the right side are not part of the broadcast – they are lights reflecting off the TV screen. (Photo Phillip Storey). video is roughly equivalent in quality to 23 megabits/second MPEG-2. This lower data rate results in a smaller bandwidth usage for the 3DTV broadcasts, saving on multiplex space. This also means that while lower transmit power is being used for the 3D trial broadcasts, the coverage is still very extensive. The final standard chosen for Nine’s 3DTV broadcasting experiment is side-by-side frames encoded as 1080i (1920x1080 pixels, 50 fields per second) with 14 megabit MPEG-4 video and 384kbps Dolby Digital AC3 audio. The transmission modulation scheme uses 16-QAM instead of the regular 64-QAM. This configuration is likely to carry over to any future permanent 3D channel from Nine/SBS and probably other channels too, at least until the possible transition to 2D plus Delta encoding. 3D television sets Assuming that you can pick up the experimental 3D signal on digital channel 40 (a re-scan may be required to find it) then all you need to watch it is a 3D television set. So how do these sets work? There are actually multiple competing technologies but by far the most common approach with consumer sets involves each viewer wearing a set of active glasses. These can fit over regular glasses and a liquid crystal shutter is mounted in each eyepiece. The glasses are powered by an internal battery, recharged by being plugged into the television set. The sets themselves are effectively just normal LCD or plasma screens but with very fast refresh rates – up to 200Hz 22  Silicon Chip (or 240Hz for 60Hz countries). They alternately display the left/right eye images at this rate. An infrared pulse is also transmitted from the set in sync with the image switching which is picked up by an IR receiver in the glasses. Using this pulse for synchronisation, each eyepiece alternately becomes opaque, ie, the left eye is blanked off while the right eye sees the right image and then the right eye is blanked off while the left eye sees the left image. The apparent refresh rate is half the actual rate, ie, 100Hz for Australia. How well does this work? We would have to say the 3D effect is fairly convincing. For those wondering what happens if you watch the set without glasses, some objects on the screen appear normal while other objects are horizontally smeared due to the double image. You can watch it but it is sometimes hard to see exactly what is going on. There are no strange colours – just a double image. This isn’t really a problem though, since you can buy multiple sets of glasses to go with each television and they can all be used simultaneously. They are relatively comfortable to wear although we don’t know how we would feel wearing them for several hours. As for competing 3D television technology, people working on the production of 3DTV tend to use a different system where the left and right eye images are differently polarised. This means that the glasses used don’t need to be synchronised to the screen – they are entirely passive. siliconchip.com.au One of seven 3D cameras used to capture the State of Origin match. A hood has been placed over the camera to protect it from the torrential rain on the night. This photo taken in the OB van shows the 3ality handheld convergence controllers (lower left) along with yet more computers and monitors. This has significant advantages when working with multiple monitors which are not synchronised, as they can be in a television production van or studio. 3D broadcast trial (on digital channel 40) provided they are in the reception area of the transmitters listed above. You will see the broadcast as two images side by side. (We wonder if you used an old-fashioned stereoscope, would you perceive it as 3D? Hmm). If you live in an area served by a UHF translator then you miss out. Sorry about that. This experiment is scheduled to end on Monday 19th July 2010 when the temporary broadcast license expires. We hope that this experiment will convince enough people that 3D television is worthwhile so that it can lead to one or more permanent 3D channels. Of course, 3D TVs can also show regular 2D programming. Broadcasters won’t necessarily show 3D all the time but it seems likely that most sport matches might be shown in 3D in just a few years time and other programming may well go to 3D shortly after. In fact, given how affordable the new 3D sets are (especially considering their size and the newness of the technology), it is likely that this will take off quickly. Certainly, anybody shopping for a new HD set will be tempted to spend some extra money to get 3D capability, with the expectation that more program material should be available in the near future. And naturally since the 3D information is encoded in a regular video stream, DVDs and BluRay discs with 3D content are already coming onto the market. So even if you aren’t (yet) in an area serviced by 3DTV broadcasts you can still get some benefits from one of the new 3D sets. So what now? In addition to the State of Origin and World Cup games, which are being broadcast live, during the day Channel Nine and SBS are broadcasting highlights of the games recorded so far. Many consumer electronics retailers will be able to receive these broadcasts and use them to demonstrate 3DTV sets. So if you want to see what 3DTV is like and you live in or near an area which is serviced by one of the aforementioned towers broadcasting the 3D signals, head into your local retailer and ask to try out one of the sets. Outside of retail hours, those games broadcast so far will be repeated on a loop so that anybody with a capable set can tune in. The number of games in the loop will likely expand as more are broadcast. What if you don’t have a 3D TV? Anyone with an MPEG4compatible TV set or set-top box will be able to receive the For more information on the Channel Nine/SBS 3DTV trial program visit http://channelnine.ninemsn.com.au/ article.aspx?id=1045700 and http://hwtheworldgame.sbs.com.au/news/1001037/SBSSC to-broadcast-World-Cup-in-3D Acknowledgement: Part of the 3D production desk at Channel Nine. The two monitors show 13 feeds, with the rackmount video processing gear arrayed below them. siliconchip.com.au We would like to thank Phillip Storey of Storey Communications and Geoff Sparke of Nine Network Australia for a tour of the 3D production facilities at Channel Nine and for providing us with the information and most of the photos (taken by Sean Frazer) in this article. July 2010  23