Is this a live action version of a Tom and Jerry cartoon?
The Cat Concerto (1946) synopsis: a classical pianist named "Tom" has his performance interrupted by an angry pest. Lots of shots of the inside of the piano.
shareAlso, it's similar to the Bugs Bunny opera cartoons Rabbit of Seville and What's Opera, Doc? (In that Elmer Fudd was trying to shoot Bugs the whole time)
The movie even climaxes with a very cartoonish, impossible fall, from which a character pops right back up, practically unscathed.