Quicktime File Format (2012-08-14).pdf

Movie AtomsSample AtomsYou define a sample-to-chunk table entry by specifying the following data elements.First chunkThe first chunk number using this table entry.Samples per chunkThe number of samples in each chunk.Sample description IDThe identification number associated with the sample description for the sample. For details on sampledescription atoms, see “Sample Description Atoms” (page 99).Figure 2-47 (page 111) shows an example of a sample-to-chunk table that is based on the data stream shownin Figure 2-32 (page 96).Figure 2-47An example of a sample-to-chunk tableFirstchunkSamplesper chunkSampledescription ID1 3 233 1 235 1 24Each table entry corresponds to a set of consecutive chunks, each of which contains the same number ofsamples. Furthermore, each of the samples in these chunks must use the same sample description. Wheneverthe number of samples per chunk or the sample description changes, you must create a new table entry. If allthe chunks have the same number of samples per chunk and use the same sample description, this table hasone entry.Sample Size AtomsYou use sample size atoms to specify the size of each sample in the media. Sample size atoms have an atomtype of 'stsz'.The sample size atom contains the sample count and a table giving the size of each sample. This allows themedia data itself to be unframed. The total number of samples in the media is always indicated in the samplecount. If the default size is indicated, then no table follows.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.111