Sample Atoms

QuickTime Movie File Format Specification, May 1996

Sample Atoms

QuickTime stores media data in samples. A sample is a single element in a sequence of time-ordered data. Samples are stored in the media, and they may have varying durations.

Figure 0-28 shows the way that samples are stored in a series of chunks in a media.

Figure 28 Samples in a media

Chunks are a collection of data samples in a media that allow optimized data access. A chunk may contain one or more samples. Chunks in a media may have different sizes, and the individual samples within a chunk may have different sizes from one another.

One way to describe a sample is to use a sample table atom. The sample table atom acts as a storehouse of information about the samples and contains a number of different types of atoms. The various atoms contain information that allows the media handler to parse the samples in the proper order. This approach enforces an ordering of the samples without requiring that the sample data be stored sequentially with respect to movie time in the actual data stream.

The next section discusses the sample table atom. Subsequent sections discuss each of the atoms that may reside in a sample table atom.

Sample Atoms

Sample Table Atoms

Sample Description Atoms

Time-to-Sample Atoms

Sync Sample Atoms

Sample-to-Chunk Atoms

Sample Size Atoms

Chunk Offset Atoms