The sample table contains all the time and data indexing of the media samples in a track. Using the tables
here, it is possible to locate samples in time, determine their type (e.g. I-frame or not), and determine their
size, container, and offset into that container.
If the track that contains the Sample Table Box references no data, then the Sample Table Box does not need
to contain any sub-boxes (this is not a very useful media track).
If the track that the Sample Table Box is contained in does reference data, then the following sub-boxes are
required: Sample Description, Sample Size, Sample To Chunk, and Chunk Offset. Further, the Sample
Description Box shall contain at least one entry. A Sample Description Box is required because it contains the
data reference index field which indicates which Data Reference Box to use to retrieve the media samples.
Without the Sample Description, it is not possible to determine where the media samples are stored. The Sync
Sample Box is optional. If the Sync Sample Box is not present, all samples are sync samples.
Annex A provides a narrative description of random access using the structures defined in the Sample Table
Box. |