The
MPEG
The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by International Organization for Standardization, ISO and International Electrotechnical Commission, IEC that sets standards for media coding, includ ...
user data feature provides a means to inject application-specific data into an MPEG
elementary stream An elementary stream (ES) as defined by the MPEG communication protocol is usually the output of an audio encoder or video encoder. An ES contains only one kind of data (e.g. audio, video, or closed caption). An elementary stream is often referred ...
. User data can be inserted on three different levels:
*The sequence level
*The
group of pictures
In video coding, a group of pictures, or GOP structure, specifies the order in which intra- and inter-frames are arranged. The GOP is a collection of successive pictures within a coded video stream. Each coded video stream consists of successi ...
(GOP) level
*The picture data level
Applications that process MPEG data do not need to be able to understand data encapsulated in this way, but should be able to preserve it.
Examples of information embedded in MPEG streams as user data are:
*
Aspect ratio
The aspect ratio of a geometry, geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side—the ratio of width to height, when the rectangl ...
information
*"Hidden" information per the
Active Format Description
In television technology, Active Format Description (AFD) is a standard set of codes that can be sent in the MPEG video stream or in the baseband Serial digital interface, SDI video signal that carries information about their aspect ratio and oth ...
specification
*
Closed captioning
Closed captioning (CC) is the process of displaying text on a television, video screen, or other visual display to provide additional or interpretive information, where the viewer is given the choice of whether the text is displayed. Closed cap ...
per the
EIA-708
CTA-708 (formerly EIA-708 and CEA-708) is the standard for closed captioning for ATSC digital television (DTV) streams in the United States and Canada. It was developed by the Consumer Electronics sector of the Electronic Industries Alliance, ...
standard
External links
ATSCDVB
ATSC
Digital television
MPEG
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