The base is original from the producer (chords and melodies), but is complemented with elements that complement the song that come from samplepacks, usually, vocal chops, guitars, wobbles sections, glitch effects. It is the standard in which most of producers work, in a project you will find MIDI files made by the producer, but also melodic loops.
Piano comes from Addictive Keys, bassline form Nexus while strings from Korg M1.
Instrument Vocal Chop
Sample pack HY2ROGEN: Deep House Vocals
Loop name hdhv_vocal_loop_08_d_dry_124bpm