An information processing device includes a control part which receives an input of information indicating one or more times in a playback time of a musical piece, and generates a file including information pertaining to a timbre control performed from each of the one or more times; and a transmission part which transmits an audio signal of the musical piece and the information pertaining to the timbre control in the file to a device which outputs a synthetic sound of a playback sound of the musical piece and a playing sound of a musical instrument.