Usually watching a concert through your phone is frowned upon. At Coachella this year, it's encouraged. The annual music festival is turning its Sahara Tent stage into an augmented reality experience. Members of the audience will be able to hold their phones up between performances and see space-themed AR elements interact with the stage and audience. The AR filters will be available through the Coachella app during both weekends of the festival, April 12-14 and April 19-21.