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Understanding The Sample Tables: An Example

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essential61 edited this page Dec 27, 2019 · 21 revisions

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(from ISO/IEC 14496-12 – MPEG-4 Part 12)

This discussion applies to the case where the mp4 file is self-contained, and has an 'mdat' box containing the media data and a 'moov' box containing the metadata that references the media data.

Annex A. of ISO/IEC 14496-12 – MPEG-4 Part 12 contains a description of how the media data is laid out within the file as an interleaved set of samples and how the sample table box container (stb1) contains a set of tables that are used to identify the position of individual samples within the file.

The text of the standard document is perfectly well written, but it greatly helps to understand the relationship between the different tables (stco, stsz, stsc etc.) through a worked example. Hence why I've written this page.

First of all some definitions from the standard:

  • chunk: contiguous set of samples for one track
  • sample: all the data associated with a single timestamp
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