One or more frames sampled from a first media item of an event are analyzed to identify one or more candidate event periods within the one or more frames. For each of the one or more frames, whether a candidate event period of the one or more candidate event periods satisfies one or more conditions is determined. Responsive to determining that the candidate event period of the one or more candidate event periods satisfies the one or more conditions, the candidate event period is identified as an actual event period used to divide a time the event. Mapping data that maps the actual event period to a timestamp associated with a respective frame of the one or more frames of the first media item is generated.