ITU-T Rec. H.264 | ISO/IEC 14496-10 version 1 refers to the first approved version of this Recommendation |
International Standard. Version 1 was approved by ITU-T on 30 May 2003. The first published version in ISO/IEC
corresponded to version 1.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 2 refers to the integrated text containing the corrections specified in the
first technical corrigendum. The first fully-published version in the ITU-T was version 2 as approved by ITU-T on
7 May 2004, due to the development of the corrigendum during the publication process. Version 2 was also published in
integrated form by ISO/IEC.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 3 refers to the integrated text containing both the first technical
corrigendum (2004) and the first amendment, which is referred to as the "Fidelity range extensions". Version 3 was
approved by ITU-T on 1 March 2005.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 4 refers to the integrated text containing the first technical corrigendum
(2004), the first amendment (the "Fidelity range extensions"), and an additional technical corrigendum (2005).
Version 4 was approved by ITU-T on 13 September 2005. In both ITU-T and ISO/IEC, the next complete published
version after version 2 was version 4.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 5 refers to the integrated version 4 text with its specification of the High
4:4:4 profile removed.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 6 refers to the integrated version 5 text after its amendment to support
additional colour space indicators. In the ITU-T, the changes for versions 5 and 6 were approved on 13 June 2006 and
were published as a single amendment.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 7 refers to the integrated version 6 text after its amendment to define
five new profiles intended primarily for professional applications (the High 10 Intra, High 4:2:2 Intra, High 4:4:4 Intra,
CAVLC 4:4:4 Intra, and High 4:4:4 Predictive profiles) and two new types of supplemental enhancement information
(SEI) messages (the post-filter hint SEI message and the tone mapping information SEI message). Version 7 was
approved by ITU-T on 6 April 2007.
ITU-T Rec. H.264 | ISO/IEC 14496-10 version 8 (the current specification) refers to the integrated version 7 text after
its amendment to specify scalable video coding in three profiles (Scalable Baseline, Scalable High, and Scalable High
Intra profiles). Version 8 was approved by the ITU-T on day month 2007.
0.5 Profiles and levels
This subclause does not form an integral part of this Recommendation | International Standard.
This Recommendation | International Standard is designed to be generic in the sense that it serves a wide range of
applications, bit rates, resolutions, qualities, and services. Applications should cover, among other things, digital storage
media, television broadcasting and real-time communications. In the course of creating this Specification, various
requirements from typical applications have been considered, necessary algorithmic elements have been developed, and
these have been integrated into a single syntax. Hence, this Specification will facilitate video data interchange among
different applications.
Considering the practicality of implementing the full syntax of this Specification, however, a limited number of subsets
of the syntax are also stipulated by means of "profiles" and "levels". These and other related terms are formally defined
in clause 3.
A "profile" is a subset of the entire bitstream syntax that is specified by this Recommendation | International Standard.
Within the bounds imposed by the syntax of a given profile it is still possible to require a very large variation in the
performance of encoders and decoders depending upon the values taken by syntax elements in the bitstream such as the
specified size of the decoded pictures. In many applications, it is currently neither practical nor economic to implement
a decoder capable of dealing with all hypothetical uses of the syntax within a particular profile.
In order to deal with this problem, "levels" are specified within each profile. A level is a specified set of constraints
imposed on values of the syntax elements in the bitstream. These constraints may be simple limits on values.
Alternatively they may take the form of constraints on arithmetic combinations of values (e.g. picture width multiplied
by picture height multiplied by number of pictures decoded per second).
Coded video content conforming to this Recommendation | International Standard uses a common syntax. In order to
achieve a subset of the complete syntax, flags, parameters, and other syntax elements are included in the bitstream that
signal the presence or absence of syntactic elements that occur later in the bitstream.
0.6 Overview of the design characteristics
This subclause does not form an integral part of this Recommendation | International Standard.