videos in AudioSet
A list of about a million ten-second YouTube clips, each labelled with the sounds in it, that Google published in 2017. Labs use it to train and test general audio and music models.
Including Rachmaninoff Prelude Opus 3 No.2 - Transcription for Organ, Chopin Etude Opus25 No11 "Winter wind", Cesar Franck Piece Heroique