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 Piano Quartet in E-flat major, K.493 (mvt III) - ChamberFest Cleveland (2015), Brahms Sextet in G major, Op. 36 - II - ChamberFest Cleveland (2013), Brahms: Quintet in F minor, Op. 34, Mvt. III - ChamberFest Cleveland (2014)