Abstract: Video cyclic sexual movement detection and synchronisation apparatus (10) includes a selector (12), an analyser (14) and a output generator (16). In use, the apparatus (10) receives an input signal (18) which comprises a sequence (94) of video frames (20), each frame (20) comprising a plurality of image areas (22). In a selection phase, the selector (12) selects one of the image areas (22) as a subject area (24) and another of the image areas (22) as a reference area 26. In an analysis phase, the analyser (14) analyses a set (28) of the video frames (20) to determine a subject speed parameter (30) which relates to the speed of movement of the subject area (24) relative to the reference area (26). In a synchronisation phase, the output generator (16) generates an output signal (38) which comprises a speed signal (40) which is dependent on the subject speed parameter (30).