Why this engineer quit his job at Facebook to found an 'interactive music' startup

Lars Rasmussen decided to leave his comfortable, fulfilling job at Facebook to dive head-first into a new startup for the same reason that a lot of founders do: Because he had an idea that he just couldn't get out of his head. 

Rasmussen had been the engineering director of the team that created Facebook for Work, the company's nascent enterprise product that's currently being tested by a handful of outside companies. 

But as he and his team hustled away on that, he and his fiance Elomida Visviki spent much of their time together working on a platform that could allow users to speed up or slow down music to reach any desired tempo. 

"I found myself doing my day job and thinking about interactive music," he told Business Insider. "That's when you know that it's time to get out."

So, Rasmussen bid Facebook farewell in April and threw himself into the startup, called Weav, full-time. 

The company has created both mixing software for musicians and a player that can be embedded in third-party apps. Right now, the products are in closed beta, and Rasmussen says he expects that to continue for the next several months. 

He envisions Weav being used in a lot of different ways, but most obviously by anyone doing a workout who wants their music to feel like it's moving with them. Similarly, a dance instructor could teach her students a new routine more easily with the same song, starting with a slower tempo and then moving up to faster speeds. 

That idea might sound familiar: In May, Spotify announced "Running," a new feature that will play users songs based on how fast they're moving.

Rasmussen doesn't to see this as a threat, but rather an indication of Spotify as a potential partner. Because Weav wants to integrate its technology into other apps, he envisions Spotify Running being filled with songs created by artists who used its music mixing software.

The key right now is getting musicians to experiment with it. Dean Gillard and Matt Ward, two well-respected producers who have worked for Rihanna, Usher, and OutKast, among others, have already made new music through Weav. You can check out their track as well as several others made by  different composers on the company's Vimeo page.

Rasmussen says the feedback so far has been good.

"They've told us that we've added an extra dimension. We like the analogy that if they were painters, it's as if we've invented a three-dimensional canvas," he says. "The quality of the art is still up to the artist - we're not manipulating anyone's existing work - but we're providing a new way to deliver music to fans. And that's an exciting challenge."

This isn't Rasmussen's first startup. Back in 2003, he and his brother founded a mapping company called Where2 Technologies that Google acquired a year later. The technology became the basis for Google Maps, and Rasmussen continued to work at Google for the next 6+ years before moving to Facebook. He's happy to be back in startup land. 

"I had missed the different kind of intensity of that 'started-in-our-living-room' type of project," he says. "I kept myself a little in the startup world by doing some advising, and I felt myself a little bit envious when I talked to those guys. So, it was a tough decision to leave Facebook, but it was definitely the right decision. I haven't regretted it at all."