Off-air home audio recordings of various television programmes have also been recovered, at least preserving the soundtracks to otherwise missing shows, and some of these (particularly from "Doctor Who") have been released on CD by the BBC following restoration and the addition of narration to describe purely visual elements. Tele-snaps, a commercial service of off-screen shots of programmes often purchased by actors and television directors to keep a record of their work in the days before videocassette recorders, have also been recovered for many lost programmes.