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 Mariinsky Orchestra Horn Quartet - Friedrich Constantin Homilius - Horn quartet B-dur Op. 38, Черепнин Н. Пьесы для квартета валторн. Tcherepnin, Nikolay - 4 pieces from suite for horn quartet.