STAMFORD, Conn. - The energy across the NBC Sports Group's sprawling headquarters during the Olympics is palpable. About 1,100 workers are jammed into every available room in the 300,000-square-foot complex, spread across every hour on the clock to produce TV broadcasts, feed online streams, and clip highlights that go viral on social media in an instant.

But for all the action, almost everything that NBC does can be seen in two small rooms that television viewers will never see.

One room is the Broadcast Operations Center. About half the size of a basketball court, it's ringed with big-screen televisions whose screens are each divided into arrays with smaller picture feeds. Behind and beneath the monitors are glass walls that keep rows upon rows of data servers cool and secure.

The BOC is the nerve center of every broadcast that enters and leaves the building. Stand in one corner and look across the room, and you can see almost every televised sports event on the planet at once.

Down a hallway is a room that's even more significant, and even smaller, only 15 feet by 20 feet or so. Behind its glass walls stands a series of slim gray towers wrapped tightly with bright yellow fiber-optic cables.

Those towers and cables, housed in a space smaller than some NBC executives' offices, contain the entire transmission of NBC's Olympics broadcasts from Rio de Janeiro to the United States.

Every second of video shot at the Olympics - including the intensely watched U.S. women's gymnastics team - passes through that small room on its way to the network's 1,800 terabytes of storage disks. That includes footage from 250 cameras used by NBC for its event coverage and broadcasts from eight studios; two in Rio and six in Stamford. There's also footage from 450 cameras used by the Olympics' host broadcast production service.

"The space you would have to have if this would have been all copper [wire] would be staggering," said Tim Canary, NBC Sports Group's vice president of engineering. "The flexibility of this is unsurpassed compared to what it used to be years ago."

Based on the data NBC published so far, diehards and casual watchers alike seem to be devouring the coverage. As of the end of Tuesday's action in Rio, viewers had consumed 852 million minutes of live streaming video online.

That already surpasses the 818 million minutes of streaming consumed during the entire 2012 London Olympics, and every event was streamed live that summer, too.

Ratings for NBC's early marquee prime-time broadcasts are down from four years ago. According to viewership data compiled by, NBC's average prime-time audience through Sunday was 26.7 million viewers. That's lower than the first-weekend averages for the 1992, 1996, 2008, and 2012 Summer Olympics.

But for the first time there are live event broadcasts in prime time on cable channels, such as NBCSN and Bravo, which further divide the audience. On Tuesday the combined prime-time audience was 36.1 million viewers. The main network NBC broadcast drew 33.4 million viewers.

Canary, NBC's engineering vice president, started working on Olympics production in 2000, when the Summer Games were first televised on cable in the U.S. Back then, everything that Americans saw was transmitted from Sydney to NBC's New York studios via two satellites.

This summer, the 132 live video feeds originating in Brazil move through four AT&T fiber-optic cables that each process 10 gigabytes of data per second.

"With the satellite, from point to point, a reporter would ask a question and there would be a big delay until he heard it. Now it's almost instantaneous," Canary said.

A few corridors away from Canary's office is the nerve center where highlights are produced for online viewing.

Eric Hamilton, director of digital video production for NBC's Olympics division, oversees a staff of around 70 people that's spread across all hours of action.

Hamilton's workers post content not only to NBC's website, but also to social platforms such as Twitter, Facebook, YouTube, and Snapchat.

Their work comes with a catch. Just because they know in real time when something happens doesn't mean highlights can go online right away.

"We often have to wait until the end of an event to publish something," Hamilton said, because pay-TV companies want viewers pushed to live streams that are restricted to cable and satellite subscribers.

Hamilton is also shadowed by NBC's long-standing philosophy of tape-delaying TV broadcasts of marquee events such as gymnastics. This year, critics of that philosophy are louder than ever, thanks largely to social media.

Fortunately, NBC's live-streaming of every event online - including those that aren't televised until prime time - puts the live action right at hand. In addition to coverage on its own website, NBC has apps for a wide range of phones, tablets, video-game consoles, and connected-TV devices.

Just as important for diehard fans, the online streams often give a much broader view of events than what's seen in the prepackaged prime-time presentations.

What sports draw the most eyeballs?

"Gymnastics things can spike like nothing else," Hamilton said.

But some out-of-the-way sports have rocketed to prominence, too. A judo match Sunday in which 112th-ranked Mathews Punza of Zambia upset sixth-ranked Golan Pollack of Israel became a viral sensation.