Synchronisation of Audio and Video Playback

摘要

A method of playing audio content to a viewer in synchronisation with a video content. The method comprises receiving and digitising an ultrasonic signal comprising ultrasonic synchronisation signal(s) encoding a respective timecode through modulation of ultrasonic carrier signal(s), a first ultrasonic carrier signal having been amplitude modulated to encode logical “1” or “0” in data-carrying segments, each data-carrying segments being followed by non-data-carrying segments in which the amplitude of the ultrasonic carrier signal does not exceed a predetermined threshold. A digitised ultrasonic synchronisation signal is processed to identify the data-carrying segments, and the corresponding timecode is extracted from the data-carrying segments. A stored audio content is played back from a playback point determined based on the timecode.

主权项

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:
a storage device for storing the audio content;a microphone module operable to receive and digitise an ultrasonic signal comprising at least one of the ultrasonic synchronisation signals;a search module arranged to identify a digitised ultrasonic synchronisation signal in the digitised ultrasonic signal;a decoding module arranged to decode the identified digitised ultrasonic synchronisation signal to determine the corresponding timecode by processing the digitised synchronisation signal to identify the data-carrying segments, and extracting the corresponding timecode from the identified data-carrying segments; anda playback module arranged to determine a playback point in the stored audio content based on the determined timecode and play the stored audio content to the viewer from the determined playback point such that the audio content is played in synchronisation with the displayed video content.