Sample table atom ('stbl')
An atom that contains information for converting from media time to sample number to sample location.
Mentioned in
Overview
This atom also indicates how to interpret the sample (for example, whether to decompress the video data and, if so, how). This section describes the format and content of the sample table atom.
The sample table atom has an atom type of 'stbl'. It can contain the sample description atom, the time-to-sample atom, the sync sample atom, the sample-to-chunk atom, the sample size atom, the chunk offset atom, and the shadow sync atom. Recent additions to the list of atom types that a sample table atom can contain are the optional sample group description and sample-to-group atoms included in Audio priming-handling encoder delay in AAC.
The sample table atom contains all the time and data indexing of the media samples in a track. Using tables, it is possible to locate samples in time, determine their type, and determine their size, container, and offset into that container.
If the track that contains the sample table atom references no data, then the sample table atom does not need to contain any child atoms (not a very useful media track).
If the track that the sample table atom is contained in does reference data, then the following child atoms are required: sample description, sample size, sample to chunk, and chunk offset. All of the subtables of the sample table use the same total sample count.
The sample description atom must contain at least one entry. A sample description atom is required because it contains the data reference index field that indicates which data reference atom 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 atom is optional. If the sync sample atom is not present, all samples are implicitly sync samples.
The layout of the sample table atom is as follows.
Data | Type |
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4 bytes | |
Type = | 4 bytes |
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Topics
Data fields
See Also
Describing samples
Seeking with a QuickTime fileSample description atom ('stsd')Time-to-sample atom ('stts')Creating video tracks at 30 frames per secondCreating video tracks at 29.97 frames per secondCreating sound tracks at 44.1 kHzComposition offset atom ('ctts')Composition shift least greatest atom ('cslg')Using composition offset and composition shift least greatest atomsSync sample atom ('stss')Partial sync sample atom ('stps')Sample-to-chunk atom ('stsc')Referencing two data files with a single trackSample size atom ('stsz')Chunk offset atom ('stco')