Riedel's profile as a composer derives almost exclusively from writing music for Astrid Lindgren movies, including the main theme from the Emil i Lönneberga ("Emil of Maple Hills") movies.
He also composed the music for several films by Arne Mattsson in the 1960s as well as for film adaptions of novels by Stig Dagerman.
Riedel also played on Jazz at the Pawnshop in 1977.