The present disclosure relates to synchronizing the rendering of video frames included in media file segments with the rendering of auxiliary media. A method implementation of this technique comprises the step of determining, from a sequence of media file segments, a sub-sequence of media file segments, wherein rendering of the sub-sequence is to be overlaid by rendering of auxiliary media starting in a first media file segment of the sub-sequence. The method further comprises determining control information enabling a media client to determine how much rendering of the auxiliary media has progressed upon rendering of each media file segment of the sub-sequence, and initiating a tagging of the media file segments of the sub-sequence with the control information.