"The Tonight Show" became the first American television program to broadcast with MTS stereo sound in 1984, at first sporadically, by audio engineer Ron Estes. Regular use of MTS began in 1985. In September 1991, the show postponed its starting time by five minutes to 11:35, to give network affiliates the opportunity to sell more advertising on their local news. On April 26, 1999, the show started broadcasting in 1080i HDTV, becoming the first American nightly talk show to be shot in that format.