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HD Slo-Mo Gets Up to Speed

Early adopters of high-definition sports production had to enter the arena without the full complement of weapons they were accustomed to using in the standard-definition world, because HD cameras were available well ahead of full HD graphics or quick-turnaround editing systems. One of the most glaring deficiencies was the lack of true HD super-slow-motion cameras, which forced directors to either forego replays or use standard-def cameras and upconvert their output.

But as HD production has skyrocketed over the past three years, so has the development of HD super-slow-motion cameras (often called “slo-mo” or “super-motion” for brevity). Leading sports camera vendors Sony and Grass Valley first introduced HD slo-mo cameras that shoot images at 2x real-time; they capture double the frames per second as a normal HD picture, 120 compared to 60. In the past year, the vendors have followed up by releasing HD cameras capable of 3x operation, or 180 frames per second, which have been integrated with the EVS replay servers that are ubiquitous in high-end sports trucks.

Moreover, the use of specialty ultra-high-frame-rate cameras, capable of capturing video at frame rates ranging from 300 to thousands of frames per second, has become commonplace as several firms have become adept at modifying cameras originally created for industrial and military applications to make them suitable for broadcast use.

These cameras tend to be used for only the most dramatic replays, as their high-frame rate means that replays also take longer, up to 20 seconds or more. In fact, the NFL’s promo campaign this fall is based on such ultra-high-frame-rate replays, which run as 30-second spots. Sports production veterans says another challenge for these ultra-high-frame-rate cameras is lighting, as they need far more light than a conventional HD camera to produce the same image quality. 

The 3x camera systems from Sony and Grass Valley, which range in price from $175,000 to $300,000, have high-quality image sensors that are capable of shooting as normal 1x cameras. They also feature the necessary interfaces to lenses and camera control units that allow them to be used seamlessly alongside conventional cameras.

“It's part of an ongoing commitment to provide all the tools that everybody was used to in SD and make them available in HD,” says Rob Willox, Sony's director of marketing for content creation, of Sony's new HDC-3300 3x camera. “The difficulty in HD is the amount of bandwidth that a super-slow-motion device takes and the transmission used for that, and getting EVS to get on board with the recorder, which they have.”

The HDC-3300 camera has improvements in its CCD imager based on technology originally developed for Sony's F23 digital cinema cameras, according to Willox. It operates on the same network as an HDC-1500 and can also be used in normal 1x mode with the flip of a switch; the 1x pictures are derived from the 3x pictures that the cameras is always capturing. Sony employs a 10-gigabit-per-second fiber connection to send the equivalent of three separate 1.5-gigabit-per-second uncompressed HD streams from the camera back to the control unit.

Regional sports channel YES Network is one of the early adopters of Sony's HDC-3300, which YES VP of Operations Ed Delaney says gives “pretty tremendous resolution.” When YES began HD production of New York Yankees games in 2004, HD super-slo-mos weren't available, so it used standard-definition slo-mo cameras and upconverted their output. In 2007, YES moved to Sony's 2x high-definition slo-mos when they became available, and this year it shifted to Sony's latest model.

YES has been using the HDC-3300 often in a left-field position with a long lens to produce replays of plays at second base, but will position it differently on the road. If the Yankees are facing a knuckleball pitcher like Boston's Tim Wakefield, YES might also place the super-slo-mo in the “low home” (plate) position. “We'll move it around depending on what the storyline is,” Delaney says.

Grass Valley's new LDK 8300 HD 3x super-slo-mo camera had a trial run during ESPN's Monday Night Football coverage last fall and was used by ABC/ESPN for its coverage of the National Basketball Association Finals this past spring. It will be employed on a full-time basis for Monday Night Football coverage this season. Based on the same camera head block as its normal-speed HD equivalent, the LDK 8000, the 8300 transmits video over a 3-gigabit-per-second fiber network. The camera uses LDK camera control systems and is compatible with LDK 8000 accessories like viewfinders and SuperXpander units.

The 8300 camera also processes images with specialized AnyLight software to cut down on image flickering, which is a common problem with slo-mo sports shots captured under artificial lighting. AnyLight, which features five presets that allow the camera operator to adjust the amount of correction required for each setup, is designed to make the image quality from the slo-mo 8300 better match that from conventional LDK units.

“It's very fancy algorithms that eliminate flicker,” says Grass Valley Marketing Manager Ken Yas. “What you might not see at 2x becomes obvious to the human eye at 3x. This is a way of making that flicker, which would normally be perceptible at 180 frames per second, go away.”

ESPN is using three different speeds of slo-mo cameras for its Monday Night Football coverage, including four Grass Valley LDK 6200 2x cameras, two of Grass Valley’s new LDK 8300 3x units, and two NAC Hi-Motion ultra-high-frame-rate cameras to capture images at 300 frames per second (the camera is capable of up to 600 frames per second). The 2x cameras run on conventional triax cable connections, while the 3x and ultra-high-frame-rate cameras run on uncompressed fiber links.

The sports giant had used Sony’s HDC-3300 3X camera last year, but switched to the Grass Valley 3x model when it became available from rental firm Bexel. According to ESPN Senior Operations Manager Steve Carter, the Grass Valley cameras fit better into the rest of ESPN’s workflow, which is based on conventional LDK units, and more closely match the pictures from those cameras.

The NAC cameras, which ESPN rents from Fletcher Chicago, are placed on a movable reverse cart and on the 50-yard line. MNF director Chip Dean says the NAC cameras, which the program began using last season, have worked well at the 300 fps rate in a variety of lighting levels, and have allowed ESPN to show detailed looks of certain plays it had a hard time analyzing with more conventional slo-mo cameras, such as blocked field goals.

“Those have been some of our best shots,” Dean says. “Traditionally, you could not see exactly what happened, as the ball is coming off a kicker’s foot pretty quick. But we’ve gotten some spectacular shots of a guy’s hand blocking the ball.”

Dean also cited a goal-line shot during a Pittsburgh Steelers-Baltimore Ravens game last year when a running back ran over several defenders en route to a touchdown: “You could see the pads moving backward and the defenders’ heads jerked back.”

The ultra-high-frame-rate cameras are a great tool, Dean says, and he was initially eager to use them frequently during a game. But he’s learned to use restraint in employing them.

“If you put them on the air too much, it takes too long and it eliminated other angles,” he says. “It also sort of took away from the special [nature] of it.”

YES has also experimented with ultra-high-frame-rate cameras, renting an Ultimate Replay unit from Fletcher in August 2006 to capture some unique replays for a Yankees-Boston Red Sox game. The shots showed then-Yankees pitcher Randy Johnson’s elbow twisting wildly with each pitch and the hitters’ bats bending under the tremendous torque of their swings. But Delaney notes that such ultra-high-frame units require a lot of light, and for night games tend to produce pictures that are grainy in comparison to YES’s normal HDC-1500 game cameras.

“You definitely see the difference,” Delaney says. “Under the right circumstances, you can get some good stuff. It was very specific, such as shooting the batter from the low-first-base side.”

Inertia Unlimited, a small firm in Jacksonville, Vt., modifies Phantom HD cameras manufactured by Vision Research into its X-Mo system. X-Mo was used by NBC for its Super Bowl coverage last February and by ABC/ESPN for the past two British Opens, and is also regularly rented by the Fox regional sports networks. The cameras rent for a list price of $3,000 to $4,000 per week, though Inertia offers significant discounts on long-term contracts.

The X-Mo can operate at variable, operator-selected rates up to 7000 frames per second and stores two-second replays on an internal solid-state storage buffer; the replays are converted to an HD-SDI output and then output to an EVS machine.

“Two to 2.5 seconds of reality is the catch-all for most sports,” says Inertia Unlimited founder and owner Jeff Silverman. “We segment as much to limit the length of the replay, so you don’t want to have a gigantic segment. We’re really thinking about how long a replay you can get into the show.”

While Silverman often hears the assertion that such ultra-high-frame-rate cameras don’t match the image quality of conventional 3x units, he disagrees, though he does concede that shooting at night requires shooting at a lower frame rate to preserve quality. He notes that the X-Mo is capable of a simultaneous 1x output, and that several customers use the 1x output as one of their regular camera feeds.

CBS uses Sony’s new 3x camera and has also employed several varieties of ultra-high-frame-rate cameras for its football, golf and tennis coverage, including Vision Research’s Phantom HD unit. Ken Aagaard, executive VP of engineering and operations for CBS Sports, says that new server technology has made it simple to quickly turn around the lengthy replays from such cameras, but that lighting remains a challenge, particularly on a cloudy day.

Nonetheless, he expects that the use of ultra-high-frame-rate cameras will increase, as they can show viewers images that previously weren’t possible, such as the topspin a big server applies to a tennis ball when it meets his racket.

“It’s a cool effect,” Aagaard says. “To some extent, it’s eye candy. But in the last couple of years, it’s become more of an analytical tool. It’s a way to show the viewer how’s that’s accomplished when the rubber hits the road, or the ball hits the racket, that we’ve never been able to share before.”