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 Mozart - Violin Sonata No. 21 in E minor, K. 304, Mozart - Violin Concerto No. 3 in G major, K. 216, "Strasbourg", Beethoven - 11 Bagatelles, op. 119