Generation method: work on pitch variation instead of notes

Currently the generation methods use the notes as midi code.
Another way to go could be to substract the midi code of the current to the previous note, leading to a stream of pitch variation instead of note.

Site questions: is the total of variation equals to zero ? If not, what is the influence on the generated music ?
A: Probably no. Global pitch will increase or decrease until reach the limit. What to do then ? Stop ? loop on pitch spectrum ?