Overview: Container structure

Container structures organize encoded streams, timing, track information and navigation within a media file.

A player needs more than a sequence of compressed bytes. It needs to identify the streams, locate useful starting points and relate their data to presentation time. This branch explains the container structures that supply those relationships, as well as the overhead and failure cases that arise when packaging is incomplete or damaged.

• What is a media container?
  A media container organizes encoded streams and the information needed to find, identify, and time them.

• Types of media containers
  Media containers use different structures to serve stored files, continuous transport, and segmented delivery.

• Multiplexing and demultiplexing
  Multiplexing combines media tracks into one organized source, while demultiplexing separates them for playback or processing.

• Elementary streams
  An elementary stream contains one coded media component before it is combined with other components in a container.

• Timing and navigation
  Container timing and navigation connect packet clocks, playback positions, seek indexes and chapter locations.

• Codec identifiers and FourCC
  Codec identifiers tell a container reader how to interpret a track's encoded data and its packaging.

• Codec support in containers
  A valid container and codec combination needs both a defined storage mapping and software that implements it.

• Track and programme descriptions
  Track and programme descriptions identify available content and provide context for selecting or routing it.

• Container overhead
  Container overhead is the space used to organize and describe media in addition to its encoded picture and sound.

• Damaged and incomplete media files
  A damaged media file can lose container structure, timing, or encoded content, with different consequences for recovery.