By Jay N. Miller For The Patriot Ledger So, there you are, filming your latest music video, made up as a vampire floating around Mandy Moore’s swimming pool in Los Angeles. It’s a long way from a Stoughton teenager cutting his musical teeth playing innumerable gigs at the old Scotch and Sounds lounge at Westgate Lanes in Brockton. But that’s just where Mike Viola’s musical journey began, a head-spinning trip that has made him one of the world’s most in-demand producers, as well as songwriter, and rocker in his own right. He’s worked with a long list of pop music royalty, from Moore to Fall Out Boy, Panic! At The Disco, Jenny Lewis, Ryan Adams and Lexington native Matt Nathanson. He’s been all over several movie soundtracks, including most prominently “That Thing You Do,” and also wrote many of the songs for the country music comedy “Walk Hard: The Dewey Cox Story.” Then there’s his current “day job,” as A&R (Artists and Repertoire) man for Universal Music and Verve, where he’s able to scout out new talent, and help guide established acts for the labels.