vivaldi helped to bring the concerto to a mainstream form, not only by expanding on ritornello form, but by emphasizing the slow movements of concertos, which were in a two part binary form. solo instruments that vivaldi wrote concertos for include violin, bassoon, cello, oboe, viola d'amore, flute and mandolin. he also wrote ensemble concertos (concerto grosso and/or chamber concerto), where three or more soloists participate, which number over 30 written. vivaldi had an extensive influence on the concerto genre, helping to pioneer the structure, expanding the boundaries of the genre, and showing that any instrument could have a concerto.