Patent ID: 9386191
Filing Date: 2016-07-05
CPC Classification: H04N

Claim Text:
1. An audio-visual presentation system for presenting audio content of an audio-visual presentation in synchronisation with video content of the audio-visual presentation to a viewer of the video content, comprising: an ultrasonic synchronisation signal generator arranged to generate a sequence of ultrasonic synchronisation signals during display of the video content, wherein each ultrasonic synchronisation signal encodes a respective timecode through amplitude modulation of one or more ultrasonic carrier signals, the ultrasonic synchronisation signal generator being arranged to generate each ultrasonic synchronisation signal by amplitude modulating a first ultrasonic carrier signal to encode a logical “1” or a logical “0” in each of a plurality of data-carrying segments of the amplitude modulated first ultrasonic carrier signal that encode the timecode, and transmitting the data-carrying segments such that each of the data-carrying segments is followed by a non-data-carrying segment in which the amplitude of the first ultrasonic carrier signal does not exceed a predetermined threshold; and a portable device for playing the audio content of the audio-visual presentation to the viewer, the portable device comprising: