The exemplary embodiments of this invention provide in one aspect thereof an ability to signal multiple decoding times for each sample in a file format level in order to allow, for example, different decoding times for each sample (or sample subset) between decoding an entire stream and decoding a subset of the stream. An alternate decoding time box is specified to allow for the signaling of multiple decoding times for each sample. Such a box can contain a compact version of a table that allows indexing from an alternate decoding time to a sample number, where an alternate decoding time is a decoding time to be used with a sample when only a subset of an elementary stream stored in a track is to be decoded. Furthermore, each entry in the table provides the number of consecutive samples with the same time delta, and the delta between those consecutive samples. By adding the deltas a complete time-to-sample map can be constructed.