Diapason literally refers to a "tuning fork" or the "pitch standard" for musical instruments. It's a less common word in everyday French, making it stand out.
In the song, Yelle sings, "Je suis chez moi mais je vis au diapason / De tes histoires et de tes moindres actions." Here, "au diapason" is used idiomatically to mean "in tune with" or "in harmony with." She's describing how she lives her life completely in sync with, and influenced by, someone else's stories and actions, even from a distance. This metaphorical use adds a layer of depth to her feeling of being consumed by another's life.
Vue D'en Face paints the picture of a restless daydreamer who escapes her own boredom by secretly people-watching the neighbors across the street. From the safety of her living-room sofa, she projects herself into their seemingly perfect world: lovers embrace, problems vanish, and every answer appears obvious. The view “from over there” feels brighter and smoother than her own reality, so she lets her imagination drift, borrowing other people’s memories and living vicariously through their daily routines.
Yet this borrowed paradise comes at a price. The more she spies, the more she sinks into the shadows of her own life—until she finally snaps out of the trance, declares “Merci, mais moi je me casse,” and rockets back into her personal space. In reclaiming her privacy, she discovers that life runs far better when she spins inside her own orbit. The song is a playful reminder that while other lives may look flawless from afar, real freedom begins the moment we stop comparing screens and start dancing to our own beat.