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 "Three Dance Episodes for Brass Octet & Percussion" - Edward Gregson., Franz Strauss: "Horn Concerto in C minor"., March: "Viva Birkinshaw" - William Rimmer