This piece was created using Magenta Studio. It's a plugin which uses machine learning to generate MIDI, all the input I had in the composition personally was to give the MIDI a sound and an arrangement, the rest is entirely based on the machine. Magenta Studio is a collection of music plugins built on Magenta’s open source tools and models. They use cutting-edge machine learning techniques for music generation.
Listen to it here: https://soundcloud.com/virginialeo/magenta/s-0ERLNP1SDFi
Find out more here: https://magenta.tensorflow.org/