A device and associated method for processing a digital information signal from a channel signal. The digital information signal is runlength limited with one or more constraints. The device comprises receiving means for receiving the channel signal and means for comparing a detected runlength with a predetermined value indicative of a minimum runlength constraint or a maximum runlength constraint of the channel signal and for generating a control signal when the detected runlength violates said constraint. The device further comprises substitute means for in response to the control signal deleting or inserting an element in the channel signal.