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.
the bass line is midi and come from analog(ableton plugin), the pad is also from ableton plug in,the synth is made with reaktor.there are extra elements from libraries like a chord,percussions and vox.
in the track there are 2 melodic loops a "synth" and a "chord" and 2 more melodic loops created by resempling that chord loop with some fx on it (filter,delay)
Sample pack ss-ahd
Loop name chord loop 09 123 fm processed