A method of generating presentation time stamps, PTSs, for motion-compensated frame-rate conversion of a sequence of frames. In one aspect, the method comprises for each new frame: determining an average difference between the capture time-stamps of recent consecutive new frames; and generating the PTS based on the capture time-stamp of a previous new frame and the average difference. In another aspect, the method comprises detecting a first cadence and a second different cadence in the sequence of frames; and generating a PTS for each new frame defined by the first cadence, such that in each case the difference between the PTSs of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.