New technology helps directors meet the demands of sports
Jun 1, 2010 12:00 PM, By David Austerberry
Sporting events draw a big investment in new technologies like 3-D.
Telegenic’s new 3-D truck is being used for live coverage of the 2010 World Cup.
While TV audiences may be migrating to online and mobile entertainment, one area where television excels is the live event, specifically sports. One of the genres where 3-D is expected to be most successful is sports. Sporting events also attract large revenues for subscription television. Put all that together, and it is easy to see why sports receive a big investment and are a focus for innovation in production techniques.
Many programs go through post production as an essential part of the workflow: selecting shots, adding VFX, color correction and finishing. The sports director has no such luxury to refine the program. He or she can select from the camera angles available on the monitor stack, use on-the-fly switcher effects like DVE moves and run replays of key action from video servers.
This places a special emphasis on what the camera delivers to the truck. To this end, point-of-view (POV) cameras give sports fans a perspective on the game that they could never see from a seat in a stadium or standing by the green.
Viewers expect unusual views of their favorite sport. They expect the tactics to be explained with graphic aids like telestrators, and they want a constant stream of statistics. Finally, they want the latest format: HD, 5.1 and even 3-D.
To meet these needs, the sports production must use custom cameras and camera support systems, logging systems, and specialized graphics systems. International events present especially complex demands, as the various broadcasters taking the feeds have different requirements, from 3-D down to a few SD highlights for use in a newscast.
For a large international event, the issue with video is to provide each broadcaster with what it wants, and there are conflicting requirements, such as whether the broadcaster's home team is playing, whether the broadcaster wants a clean feed or if it needs the house graphics. On the audio side, the complexity comes from providing facilities for the different commentary that each broadcaster will want to add. Even a national event may have to deal with some of these issues if more than one language is spoken in that country.
Acquisition
To present the director with the optimum choice, the acquisition of video and audio is key. Sharp, well-exposed and shaded pictures with great composition go a long way to easing the task of the director, and technology can help. For the audio, careful selection of microphone type, polar diagram and surround configuration, plus good placement, can all add up to create an exciting sound design.
Much of sports coverage cannot be achieved with fixed cameras, and the wireless link frees a camera of all tethers.
Wireless
Wireless cameras have been around for a long time, but the technology has been steadily improving. Cameras and links are expected to support HD and to reliably backhaul signals from fast-moving vehicles and helicopters.
International sporting events demand commentaries in many languages. The commentary facility boxes shown are from Glensound.
Deep interleaving is a new technique that helps reduce interference caused by signals' loss of seconds. This could be from ground to air, when the transmitter is temporarily obscured by bridges or other obstacles, or from air to ground, where obstacles like trees may obscure the helicopter.
Sports that take place over a large area, such as marathons and motor racing, have been limited in the past to provide wireless coverage without setting up relays. Borrowing concepts from the phone industry, it is possible to extend diversity reception to use cellular diversity, with use of cellular receive zones and the camera able to move freely between cells.
Recent developments in modulation use COFDM, but with parameters modified from regular DVB-T to provide optimum performance for contribution circuits (DVB-T being optimized for distribution), much as DVB-T2 improves performance over the original COFDM systems. Typically, 19Mb/s can be delivered over a wireless link. To achieve the low latency needed in sports coverage, an I-frame-only video codec is necessary.
Cameras, auto-focus and image stabilization
Camera Corps’ Q-Ball with remote pan and tilt provides HD images from a compact yet rugged system.
The move to HD displayed on large screens means that focus errors, camera movement and vibration are more obvious. Many sports applications need a long focal length to achieve closeups from remote camera positions. A long focal length means small depth of field, making focus adjustment critical. In a football stadium, a camera could be 100m from the penalty box, and a focal length of 900mm would be needed to get a head and torso shot of a player. This is an angle of view of less than one degree, so it requires little motion to create a pixel of movement.
Many phenomena can cause visible movement, such as wind on a scaffolding platform, but even the most solid stadium can move when the crowd gets excited. The camera platform in a stadium is typically high up on the roof, and on maximum focal length, vibration can be easily visible to the viewer.
Auto-focus is a standard feature of consumer camcorders. Some more experienced operators may feel auto-focus is not for them, but long-focus shots of moving objects would test even the most experienced operator to maintain sharp focus. Here technology can help.
Image stabilization is also commonplace in consumer camcorders, and for aerial shots, large gyro-stabilized mounts can remove the effects of helicopter motion. To apply the concepts to large box lenses, different design concepts are called for, but several field lenses are now available with image stabilization.
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