Recording music outside, especially in a populated area, is an intimidating arrangement. You never know what mass transit, barking dogs, or emergency-vehicle sirens are going to pass by and muddy up the mix. But if you’re willing to embrace the chaos, you can get paid back with magical ambiance. That concept was the linchpin of the hit 2014 film Begin Again, which starred Mark Ruffalo as a music executive who persuaded a young singer, played by Keira Knightley, to record an album outside in public spaces around New York City.