A method of encoding a signal comprising: receiving, over time, a sequence of input frames that comprise the signal; encoding a first frame of the sequence of input frames as an independently decodable frame and assigning the first frame as a current reference frame; encoding subsequently received input frames, in the sequence of input frames, each as a difference frame that represents a difference between the input frame and the current reference frame; transmitting, after each is encoded, the independently decodable frame and each of the difference frames to a receiver; receiving, from the receiver in response to the receiver decoding a current frame, one or more acknowledgements each comprising one or more indicators, the one or more indicators signifying the outcomes of decoding a plurality of prior frames and the current frame; switching to safe mode when one of the one or more received acknowledgements includes an indicator signifying the outcome of the decoding of an associated difference frame was unsuccessful, and, when in the safe mode, assigning an input frame corresponding to a difference frame associated with a received acknowledgment, of the one or more acknowledgements, that includes a positive indication of successful decoding of said input frame as the current reference frame; and switching to normal mode when an abatement criterion is met, and, when in the normal mode, assigning an input frame as the current reference frame regardless of receiving an acknowledgement associated with a difference frame corresponding to the input frame. receiving, over time, a sequence of input frames that comprise the signal; encoding a first frame of the sequence of input frames as an independently decodable frame and assigning the first frame as a current reference frame; encoding subsequently received input frames, in the sequence of input frames, each as a difference frame that represents a difference between the input frame and the current reference frame; transmitting, after each is encoded, the independently decodable frame and each of the difference frames to a receiver; receiving, from the receiver in response to the receiver decoding a current frame, one or more acknowledgements each comprising one or more indicators, the one or more indicators signifying the outcomes of decoding a plurality of prior frames and the current frame; switching to safe mode when one of the one or more received acknowledgements includes an indicator signifying the outcome of the decoding of an associated difference frame was unsuccessful, and, when in the safe mode, assigning an input frame corresponding to a difference frame associated with a received acknowledgment, of the one or more acknowledgements, that includes a positive indication of successful decoding of said input frame as the current reference frame; and switching to normal mode when an abatement criterion is met, and, when in the normal mode, assigning an input frame as the current reference frame regardless of receiving an acknowledgement associated with a difference frame corresponding to the input frame. switching to safe mode when one of the one or more received acknowledgements includes an indicator signifying the outcome of the decoding of an associated difference frame was unsuccessful, and, when in the safe mode, assigning an input frame corresponding to a difference frame associated with a received acknowledgment, of the one or more acknowledgements, that includes a positive indication of successful decoding of said input frame as the current reference frame; and switching to normal mode when an abatement criterion is met, and, when in the normal mode, assigning an input frame as the current reference frame regardless of receiving an acknowledgement associated with a difference frame corresponding to the input frame.