Dx_envelope
val scale_output_level : int -> int
val floor : float
val gain : float -> float
val decibels : float -> float
type t
val create : rates:int array -> levels:int array -> ?output_level:int -> ?rate_scaling:int -> unit -> t
val key_up : t -> unit
val next : t -> float
val run : t -> int -> float
val stage : t -> int