US band Bluebrain have released their third location-based album as an iPhone app. It’s called Violet Crown, and is designed to be listened to while walking around the SXSW festival in Austin this month. “Each street and intersection is tagged with distinct musical zones that blend from one to another as the listener traverses the streets. Think of it as a choose-your-own-adventure of an album,” explains its App Store listing. The album follows previous releases The National Mall and Listen To The Light, which were for locations in Washington DC and New York’s Central Park respectively. Like those two previous apps, Violet Crown is free to download, but it won’t work outside the boundaries of SXSW.