A method for processing audio content and video content of an audio/video program, wherein the method comprises: receiving a sequence of audio packets conveying first control information and the audio content and obtaining from the first control information audio time information for a respective audio packet in the sequence of audio packets; receiving a sequence of video packets conveying second control information and the video content and obtaining from the second control information video time information for a respective video packet in the sequence of video packets; determining from the audio time information and the video time information a relative time alignment of the respective audio packet with the respective video packet and applying a perceptual model to the relative time alignment to obtain a measure of perceived misalignment between the respective audio packet and the respective video packet, wherein the perceptual model is based on timing thresholds; characterized in that if the measure of perceived misalignment indicates the respective audio packet precedes the desired time alignment with the respective video packet by an interval that exceeds a first threshold, delaying all or part of the respective audio packet by a first amount such that according to the perceptual model a perceived misalignment between the delayed respective audio packet and the respective video packet is reduced; if the measure of perceived misalignment indicates the respective audio packet follows the desired time alignment with the respective video packet by an interval that exceeds a second threshold, delaying the respective video packet by a second amount and delaying all or part of the respective audio packet by a third amount such that according to the perceptual model a perceived misalignment between the delayed respective audio packet and the delayed respective video packet is reduced; inserting information into an audio data stream that is generated from all or part of the respective audio packet that is delayed; and reducing playback levels of audio content preceding the inserted information and increasing playback levels of audio content following the inserted information. receiving a sequence of audio packets conveying first control information and the audio content and obtaining from the first control information audio time information for a respective audio packet in the sequence of audio packets; receiving a sequence of video packets conveying second control information and the video content and obtaining from the second control information video time information for a respective video packet in the sequence of video packets; determining from the audio time information and the video time information a relative time alignment of the respective audio packet with the respective video packet and applying a perceptual model to the relative time alignment to obtain a measure of perceived misalignment between the respective audio packet and the respective video packet, wherein the perceptual model is based on timing thresholds; characterized in that if the measure of perceived misalignment indicates the respective audio packet precedes the desired time alignment with the respective video packet by an interval that exceeds a first threshold, delaying all or part of the respective audio packet by a first amount such that according to the perceptual model a perceived misalignment between the delayed respective audio packet and the respective video packet is reduced; if the measure of perceived misalignment indicates the respective audio packet follows the desired time alignment with the respective video packet by an interval that exceeds a second threshold, delaying the respective video packet by a second amount and delaying all or part of the respective audio packet by a third amount such that according to the perceptual model a perceived misalignment between the delayed respective audio packet and the delayed respective video packet is reduced; inserting information into an audio data stream that is generated from all or part of the respective audio packet that is delayed; and reducing playback levels of audio content preceding the inserted information and increasing playback levels of audio content following the inserted information.