On-demand Internet radio is nothing new, but New York Public Radio hopes to take the concept to the next level by providing theme customized and time-based offline playlists that cater to public radio listeners’ specific preferences. NYPR’s new Discovery feature, a part of the organization’s WNCY mobile app, lets listeners choose the topics they’re interested in and how long they’d like to listen, and then creates and downloads a custom playlist of public radio show segments that meet those criteria.