Every sampling artist will tell you that music is everywhere, but there was a strict production process that turned the sounds of everyday life into something you could call a song. RJDJ, an interactive iPhone app, allows anyone to make a sampled song on the fly through a process that is hard to describe unless you hear it happening — hence the video. Check out the demo and see if you can figure it out. The result is an impromptu composition that the creators describe as “reactive music” and has a good chance of influencing music in the future.