2 Rec. ITU-T H.266 (08/2020)
in Annex C. These VUI parameters and SEI messages may be used together with this Recommendation | International
Standard.
Versions of this Recommendation | International Standard
This is the first version of this Recommendation | International Standard.
Overview of the design characteristics
The coded representation specified in the syntax is designed to enable a high compression capability for a desired image
or video quality. The algorithm is typically not mathematically lossless, as the exact source sample values are typically not
preserved through the encoding and decoding processes, although some modes are included that provide lossless coding
capability. A number of techniques are specified to enable highly efficient compression. Encoding algorithms (not
specified within the scope of this Recommendation | International Standard) may select between inter, intra, intra block
copy (IBC), and palette coding for block-shaped regions of each picture. Inter coding uses motion vectors for block-based
inter-picture prediction to exploit temporal statistical dependencies between different pictures, intra coding uses various
spatial prediction modes to exploit spatial statistical dependencies in the source signal within the same picture, and intra
block copy coding uses block displacement vectors to reference previously decoded regions of the same picture to exploit
statistical similarities among different areas of the same picture. Motion vectors, intra prediction modes, and IBC block
vectors are specified for a variety of block sizes in the picture. The prediction residual can then be further compressed
using a spatial transform to remove spatial correlation inside a block before it is quantized, producing a possibly irreversible
process that typically discards less important visual information while forming a close approximation to the source
samples. Finally, the motion vectors, intra prediction modes, and block vectors can also be further compressed using a
variety of prediction mechanisms, and, after prediction, are combined with the quantized transform coefficient information
and encoded using arithmetic coding.
How to read this document
It is suggested that the reader starts with clause 1 and moves on to clause 3. Clause 6 should be read for the geometrical
relationship of the source, input, and output of the decoder. Clause 7 specifies the order to parse syntax elements from the
bitstream. See clauses 7.1 to 7.3 for syntactical order and clause 7.4 for semantics; e.g., the scope, restrictions, and
conditions that are imposed on the syntax elements. The actual parsing for most syntax elements is specified in clause 9.
Finally, clause 8 specifies how the syntax elements are mapped into decoded samples. Throughout reading this document,
the reader should refer to clauses 2, 4, and 5 as needed. Annexes A through D also form an integral part of this
Recommendation | International Standard.
Annex A specifies profiles, each being tailored to certain application domains, and defines the so-called tiers and levels of
the profiles. Annex B specifies syntax and semantics of a byte stream format for delivery of coded video as an ordered
stream of bytes. Annex C specifies the hypothetical reference decoder, bitstream conformance, decoder conformance, and
the use of the hypothetical reference decoder to check bitstream and decoder conformance. Annex D specifies syntax and
semantics for supplemental enhancement information (SEI) message payloads that affect the conformance specifications
in Annex C. Rec. ITU-T H.274 | ISO/IEC 23002-7 specifies the syntax and semantics of the video usability information
(VUI) parameters as well as SEI messages that do not affect the conformance specifications in Annex C. These VUI
parameters and SEI messages may be used together with this Recommendation | International Standard.
1 Scope
This Recommendation | International Standard specifies a video coding technology known as Versatile Video Coding
(VVC), comprising a video coding technology with a compression capability that is substantially beyond that of the prior
generations of such standards and with sufficient versatility for effective use in a broad range of applications.
Only the syntax format, semantics, and associated decoding process requirements are specified, while other matters such
as pre-processing, the encoding process, system signalling and multiplexing, data loss recovery, post-processing, and video
display are considered to be outside the scope of this Recommendation | International Standard. Additionally, the internal
processing steps performed within a decoder are also considered to be outside the scope of this Recommendation |
International Standard; only the externally observable output behaviour is required to conform to the specifications 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 include, but are not limited to, video coding for
digital storage media, television broadcasting and real-time communication. In the course of creating this
Recommendation | International Standard, various requirements from typical applications have been considered, necessary