Musical performance is considered from the points of view of interpretation and nuance, the former requiring mainly analytical, the latter technical skills. Interpretation is understood as finding a structure in a musical text by its segmentation and determining the relation between Gestalt segments. Nuancing is understood as a means of showing the segments by intonation patterns. A system of rules has been developed which aim to do segmentation and the First Movement of Vivaldi's Violin Concerto in G major (Op.3 No.3) is taken as an example of how to use the analysis-based method for the interpretation. The interpretation has been realized both by a computer and by a violin pupil appropriately instructed.