Systems and techniques are described for processing media content, such as samples of sparse media content whose sample durations can be unknown at the time of decoding the samples, include obtaining, at a current time instance, a current fragment comprising at least a current time component. From the current time component, a modified duration is obtained for at least one media sample, the modified duration indicating a time duration by which a presentation of a previous media sample of a previous fragment is to be extended or reduced in relation to the current time instance. The at least one media sample is presented for a time duration based on the modified duration.