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.
Drums, Vocals, FX-es are samples.
The slap bassline is a melodic loop from a sample pack.
(Baltic Audio Slap House Bass Loops, BASHBL01 Bassloop 08 125bpm Gmin SC)
The other basses and synths are from Sylenth and VPS Avenger.
Except the slap bassline the other melodies and midi’s are fully original.
Sample pack Baltic Audio Slap House Bass Loops
Loop name BASHBL01 Bassloop 08 125bpm Gmin SC