Synchronizing devices using clock signal delay comparison

A method of estimating a time difference between an occurrence of a first event and an occurrence of a second event, the method comprising:

• generating a first time marker in response to the occurrence of the first event;
• generating a second time marker in response to the occurrence of the second event;
• receiving the first time marker;
• receiving the second time marker and delaying the second time marker so as to provide a plurality of delayed versions of the second time marker, each delayed version being delayed by a different amount of delay to the other delayed versions;
• comparing each of the delayed versions of the second time marker with the first time marker so as to identify which of the delayed versions of the second time marker is the closest temporally matching time marker to the first time marker;
• and
• estimating the time difference between the first and second time markers in dependence on the identified delayed version;
• wherein the first event and/or the second event is one of playing a media frame or receiving a beacon, and the estimated time difference provides a measure of a time delay relative to a time of playing the media frame or a time of receiving the beacon.

A non-transitory computer readable storage medium having stored thereon computer readable instructions that, when executed at a computer system, cause the computer system to perform a method of estimating a time difference between an occurrence of a first event and an occurrence of a second event, the method comprising:

• generating a first time marker in response to the occurrence of the first event;
• generating a second time marker in response to the occurrence of the second event;
• receiving the first time marker;
• receiving the second time marker and delaying the second time marker so as to provide a plurality of delayed versions of the second time marker, each delayed version being delayed by a different amount of delay to the other delayed versions;
• comparing each of the delayed versions of the second time marker with the first time marker so as to identify which of the delayed versions of the second time marker is the closest temporally matching time marker to the first time marker, and
• estimating the time difference between the first and second time markers in dependence on the identified delayed version;
• wherein the first event and/or the second event is one of playing a media frame or receiving a beacon, and the estimated time difference provides a measure of a time delay relative to a time of playing the media frame or a time of receiving the beacon.