All right, Halloween is coming. And who can tell with this crowd? We dress scary every day,” subversive filmmaker John Waters, the emcee of Halloween Meltdown in Oakland said, before inviting onto the stage the hosts for this year’s costume contest — artists Shannon Shaw and Brontez Purnell. The crowd, gathered at the small amphitheater in Mosswood Park, witnessed a series of performances by Naked Roommate, Drug Apts and Chaki The Funk Wizard, and eagerly waited for their turn to hop on the stage and play their characters at the costume contest on Saturday afternoon. The two-day concert lineup included Body Double, Seth Bogart, Bodhi’s War and more, with Osees headlining Saturday and The Mummies topping the bill Sunday.