ISO/IEC 23002-7:2022 情報技術 — MPEG ビデオ技術 — Part 7: 符号化されたビデオ ビットストリーム用の多用途の補足拡張情報メッセージ | ページ 6

3.1

AU

access unit

set of PUs that belong to different layers and contain coded pictures associated with the same output time

3.2

APS

adaptation parameter set

syntax structure containing syntax elements that apply to zero or more slices as determined by zero or more syntax elements found in slice headers

3.3

alpha blending

process in which an auxiliary coded picture is used in combination with a primary coded picture and with other data not specified by this document in the display process

Note 1 to entry: In an alpha blending process, the luma samples of an auxiliary coded picture are interpreted as indications of the degree of opacity (or, equivalently, the degrees of transparency) associated with corresponding samples of the primary coded picture.

3.4

associated IRAP picture

previous IRAP picture (when present) in decoding order, for a particular picture, in the same layer as the particular picture

3.5

azimuth circle

circle on a sphere connecting all points with the same azimuth value

Note 1 to entry: An azimuth circle is always a great circle like a longitude line on the earth.

3.6

byte

sequence of 8 bits, within which, when written or read as a sequence of bit values, the left-most and right-most bits represent the most and least significant bits, respectively, and the bits are written or read from left to right

3.7

chroma

sample array or single sample representing one of the two colour difference signals related to the primary colours, represented by the symbols Cb and Cr

Note 1 to entry: The term chroma is used rather than the term chrominance in order to avoid implying the use of linear light transfer characteristics that is often associated with the term chrominance.

3.8

CLVS

coded layer video sequence

sequence of PUs of the same layer that consists, in decoding order, of a CLVSS PU, followed by zero or more PUs that are not CLVSS PUs, including all subsequent PUs up to but not including any subsequent PU that is a CLVSS PU

3.9

CLVSS PU

PU in which the coded picture is a CLVSS picture

3.10

CLVSS

coded layer video sequence start

coded picture that starts a new CLVS as specified in a video coding specification

Note 1 to entry: In Rec. ITU-T H.266 | ISO/IEC 23090-3, a CLVSS picture is an IRAP picture with NoIncorrectPicOutputFlag equal to 1 or a gradual decoding refresh picture with NoIncorrectPicOutputFlag equal to 1. In Rec. ITU-T H.265 | ISO/IEC 23008-2, a CLVSS picture is an IRAP picture with NoRaslOutputFlag equal to 1.

3.11

coded picture

coded representation of a picture containing all CTUs of the picture

3.12

coded slice NAL unit

NAL unit that contains a coded slice

3.13

coded video bitstream

sequence of bits that forms the representation of a sequence of AUs forming one or more CVSs

3.14

CVS

coded video sequence

sequence of AUs that consists, in decoding order, of a CVSS AU, followed by zero or more AUs that are not CVSS AUs, including all subsequent AUs up to but not including any subsequent AU that is a CVSS AU

3.15

CVSS AU

AU that has a PU for each layer present in the CVS and the coded picture in each PU is a CLVSS picture

3.16

component

array or single sample from one of the three arrays (luma and two chroma) that compose a picture in 4:2:0, 4:2:2, or 4:4:4 colour format or the array or a single sample of the array that compose a picture in monochrome format

3.17

constituent picture

part of a spatially frame-packed stereoscopic picture that corresponds to one view, or a picture itself when frame packing is not in use or the temporal interleaving frame packing arrangement is in use

3.18

cropped decoded picture

result of cropping a decoded picture based on the conformance cropping window for the corresponding coded picture

3.19

decoded picture

decoded picture is derived by decoding a coded picture

3.20

decoder

embodiment of a decoding process

3.21

decoding order

order in which syntax elements are conveyed in the coded video bitstream and are processed by a decoding process

3.22

decoding process

process that reads a coded video bitstream and derives decodedpictures from it

3.23

elevation circle

circle on a sphere connecting all points with the same elevation value

Note 1 to entry: An elevation circle is similar to a lattitude line on the earth. Except when the elevation value is zero, an elevation circle is not a great circle like a longitude circle on the earth.

3.24

encoder

embodiment of an encoding process

3.25

encoding process

process that produces a coded video bitstream

3.26

field

assembly of alternative rows of samples of a frame

3.27

flag

variable or single-bit syntax element that can take one of the two possible values: 0 and 1

3.28

frame

composition of a top field and a bottom field, where sample rows 0, 2, 4, ... originate from the top field and sample rows 1, 3, 5, ... originate from the bottom field

3.29

global coordinate axes

coordinate axes associated with omnidirectional video that are associated with an externally referenceable position and orientation

Note 1 to entry: The global coordinate axes could correspond to the position and orientation of a device or rig used for omnidirectional audio/video acquisition as well as the position of an observer's head in the three-dimensional space of the omnidirectional video rendering environment.

3.30

great circle

intersection of a sphere and a plane that passes through the centre point of the sphere

Note 1 to entry: A great circle is also known as an orthodrome or Riemannian circle.

3.31

inter prediction

aspect of the decoding process for a coded picture that makes use of data derived from the decoding process of one or more previously decoded reference pictures

3.32

IRAP picture

coded picture starting from which all pictures in the same layer in both decoding order and output order can be decoded without first decoding any picture in the same layer earlier in decoding order in the coded video bitstream

3.33

layer

set of VCL NAL units that all have a particular value of layer identifier and the associated non-VCL NAL units, wherein the layer identifier is a variable for which the value is specified by a video coding specification

Note 1 to entry: In the contexts of Rec. ITU-T H.266 | ISO/IEC 23090-3 and Rec. ITU-T H.265 | ISO/IEC 23008-2, the layer identifier is the value of the nuh_layer_id syntax element in the NAL unit header.

3.34

leading picture

picture that is in the same layer as the associated IRAP picture and precedes the associatedIRAP picture in output order

3.35

local coordinate axes

coordinate axes having a specified rotation relationship relative to the global coordinate axes

3.36

luma

sample array or single sample representing the monochrome signal related to the primary colours, represented by the symbol or subscript Y or L

Note 1 to entry: The term luma is used rather than the term luminance in order to avoid implying the use of linear light transfer characteristics that is often associated with the term luminance. The symbol L is sometimes used instead of the symbol Y to avoid confusion with the symbol y as used for vertical location.

3.37

NAL unit

syntax structure containing an indication of the type of data that follows and bytes containing that data in a manner that enables the extraction of a string of data bits from the syntax structure

3.38

non-VCL NAL unit

NAL unit that is not a VCL NAL unit

3.39

omnidirectional video

video content in a format that enables rendering according to the user's viewing orientation, e.g., if viewed using a head-mounted device, or according to a user's desired viewport, reflecting a potentially rotated viewing position

3.40

output order

order in which the decodedpictures are output from the decoder (for the decoded pictures that are to be output from the decoder)

3.41

output time

time when a decodedpicture is to be output from the decoder (for the decoded pictures that are to be output from the decoder)

3.42

packed region

region in a region-wise packed picture that is mapped to a projected region according to a region-wise packing

3.43

picture

array of luma samples in monochrome format or an array of luma samples and two corresponding arrays of chroma samples in 4:2:0, 4:2:2, and 4:4:4 colour format

Note 1 to entry: A picture could be either a frame or a field. However, in one CLVS, either all pictures are frames or all pictures are fields.

3.44

PPS

picture parameter set

A syntax structure containing syntax elements that apply to zero or more entire coded pictures as determined by a syntax element that is the same for all slices of a picture and found in the picture header or slice headers of each picture

3.45

PU

picture unit

set of NAL units that contain all VCL NAL units of a coded picture and their associated non-VCL NAL units

3.46

projected picture

picture that uses a projection format for omnidirectional video

3.47

projected region

region in a projected picture that is mapped to a packed region according to a region-wise packing

3.48

projection

specified correspondence between the colour samples of a projected picture and azimuth and elevation positions on a sphere

3.49

random access

act of starting the decoding process for a coded video bitstream at a point other than the beginning of the bitstream

3.50

RASL picture

leading picture that cannot be correctly decoded when the decoding process starts from the associated IRAP picture

3.51

reference picture

picture that contains samples that could be used for inter prediction in the decoding process of subsequent pictures in decoding order

3.52

reference picture list

list of reference pictures that is used for inter prediction of a slice

3.53

region-wise packed picture

decoded picture that contains one or more packed regions

Note 1 to entry: A region-wise packed picture could contain a region-wise packing of a projected picture.

3.54

region-wise packing

transformation, resizing, and relocation of packed regions of a region-wise packed picture to remap the packed regionstoprojected regions of a projected picture

3.55

sample aspect ratio

indicated width-to-height aspect ratio of the luma samples of the associated decoded pictures

3.56

slice

region of a picture that can be decoded separately from other regions of the same coded picture (although in some cases the decoding process for the picture might use inter prediction that makes reference to other previously decoded reference pictures)

3.57

source

term used to describe the video material or some of its attributes before encoding

3.58

sphere coordinates

azimuth and elevation angles identifying a location of a point on a sphere

3.59

sphere region

region on a sphere, specified either by four great circles or by two azimuth circles and two elevation circles, or such a region on a rotated sphere after applying yaw, pitch, and roll rotations

3.60

STSA picture

coded picture that enables up-switching, at the coded picture, to the temporal sublayer containing the coded picture, from the immediately lower temporal sublayer of the same layer when the coded picture does not belong to the lowest temporal sublayer

Note 1 to entry: An STSA picture does not use pictures in the same layer and with the same temporal sublayer identifier as the STSA picture for inter prediction reference. Pictures following an STSA picture in decoding order in the same layer and with the same temporal sublayer identifier as the STSA picture do not use pictures prior to the STSA picture in decoding order in the same layer and with the same temporal sublayer identifier as the STSA picture for inter prediction reference. STSA pictures in an independent layer (i.e., a layer that does not depend on other layers in its decoding) always have a temporal sublayer identifier greater than 0.

3.61

syntax element

element of data represented in a syntax structure

3.62

syntax structure

zero or more syntax elements that are present together in a specified order in a string of data bits, where the left-most bit is considered to be the first and most significant bit, and the right-most bit is considered to be the last and least significant bit

3.63

SEI message

syntax structure that provides a particular type of information that assists in processes related to decoding, display or other purposes but is not needed by the decoding process in order to determine the values of the samples in decoded pictures

3.64

temporal sublayer

subset of a temporal scalable bitstream, consisting of VCL NAL units with a particular value of temporal sublayer identifier and the associated non-VCL NAL units

3.65

temporal sublayer identifier

number greater than or equal to 0 defined by a variable for which the value is specified by a video coding specification such that pictures of all temporal sublayers have a specified temporal output order relative to each other and pictures with a lower temporal sublayer identifier can be decoded without reference to pictures with a higher temporal sublayer identifier

3.66

tilt angle

angle indicating the amount of tilt of a sphere region, measured as the amount of rotation of a sphere region along the axis originating from the sphere origin passing through the centre point of the sphere region, where the angle value increases clockwise when looking from the origin towards the positive end of the axis

3.67

trailing picture

coded picture that is associated with an IRAP picture and follows the IRAP picture in both decoding order and output order

3.68

VCL NAL unit

collective term for coded slice NAL units and the subset of other NAL units that have reserved values of NAL unit type identifiers that are classified as VCL NAL units in a referencing specification

3.69

VUI parameters

syntax structure that identifies properties of interpretation of decoded pictures for display purposes, particularly including colour representation information

3.70

viewport

region of omnidirectional video content suitable for display and viewing by the user