The Carl and Ruth Shapiro Family National Center for Accessible Media (NCAM) at WGBH in Boston is permanently waiving license fees for its patented movie-theater captioning system, to celebrate the 20th anniversary of its work to improve media for users with disabilities. Larry Goldberg, WGBH’s director of media access and head of NCAM, told Current that most theaters have made a one-time payment of around $2,000 for the license. The center hopes the waiver will encourage more theaters to offer Rear Window Captioning, one of several systems available for viewers who are deaf or hard of hearing. More than 400 theaters nationwide have installed the technology since it was first available in 1996, WGBH said in a statement. To use Rear Window, viewers look into clear panels in front of their seats that reflect a large LED screen on the theater’s back wall displaying captions in mirror image.