ISO/IEC 14496-12:2020 情報技術—視聴覚オブジェクトのコーディング—パート12：ISOベースメディアファイル形式 | ページ 6

3.1.1

box

object-oriented building block defined by a unique type identifier and length

Note 1 to entry: Called ‘atom’ in some specifications, including the first definition of MP4.

3.1.2

chunk

contiguous set of samples for one track

3.1.3

clean aperture

part of a decoded video image from which undesirable pixels introduced for coding purposes such as having integer number of coding blocks have been removed for presentation

3.1.4

container box

box whose sole purpose is to contain and group a set of related boxes

Note 1 to entry: Container boxes are normally not derived from FullBox.

3.1.5

file level

byte position in an ISO base media file not contained in a Box structure

3.1.6

full aperture

decoded video image as output by the decoder which may contain undesirable pixels for presentation

3.1.7

hint track

special track which does not contain media data, but instead contains instructions for packaging one or more tracks into a streaming channel

3.1.8

hinter

tool that is run on a file containing only media, to add one or more hint tracks to the file and so facilitate streaming

3.1.9

index file

ISO base media file containing only SegmentIndexBox

3.1.10

ISO base media file

file conforming to the file format described in this document (either a movie file, a metadata file, a segment file or an index file)

3.1.11

item

data which does not require timed processing, as opposed to sample data

3.1.12

leading sample

sample associated with a random access point (RAP) that precedes the RAP in composition order and immediately follows the RAP or another leading sample in decoding order, and which possibly cannot be correctly decoded when decoding starts from the RAP

3.1.13

leaf subsegment

subsegment that does not contain any indexing information that would enable its further division into subsegments

3.1.14

mod

modulo operator: (x mod y) = x-y floor (x/y)

3.1.15

media data box

box which can hold the actual media data for a presentation ('mdat')

3.1.16

metadata file

ISO base media file containing a top-level MetaBox

Note 1 to entry: A Movie File may also be a Metadata File, and vice-versa.

3.1.17

movie box

container box whose sub-boxes define the metadata for a presentation ('moov')

3.1.18

movie file

ISO base media file containing a MovieBox

3.1.19

movie fragment

fragment of the information contained in a MovieBox, defined by a MovieFragmentBox and its contents

3.1.20

movie-fragment relative addressing

signalling of offsets for media data in movie fragments that is relative to the start of those movie fragments, specifically setting the flags base-data-offset-present to 0 and default-base-is-moof to 1 in TrackFragmentHeaderBoxes

Note 1 to entry: Setting the default-base-is-moof flag to 1 is only relevant for movie fragments that contain more than one track run (either in the same or several tracks).

3.1.21

open random access point

sample after which all samples in composition order can be correctly decoded, but some samples following the random access point in decoding order and preceding the random access point in composition order need not be correctly decodable

Note 1 to entry: For example, an intra picture starting an open group of pictures can be followed in decoding order by (bi-)predicted pictures that however precede the intra picture in composition order; though they possibly cannot be correctly decoded if the decoding starts from the intra picture, they are not needed.

3.1.22

pixel aspect ratio

scaling required to be applied to the output pixel of a decoder to produce a non-distorted image

Note 1 to entry: The term"Sample Aspect Ratio" is sometimes used for this term, but"sample" in this standard has a specific meaning.

3.1.23

presentation

one or more motion sequences, possibly combined with audio

3.1.24

presentation time

composition time of a sample, as adjusted by any edit list

3.1.25

random access point

RAP

sample in a track that starts at the ISAU of a SAP of type 1 or 2 or 3; informally, a sample, from which when decoding starts, the sample itself and all samples following in composition order can be correctly decoded

Note 1 to entry: SAP types are defined in Annex I.

3.1.26

random access recovery point

sample in a track with presentation time equal to the TSAP of a SAP of type 4; informally, a sample, that can be correctly decoded after having decoded a number of samples that is before this sample in decoding order, sometimes known as gradual decoding refresh

Note 1 to entry: SAP types are defined in Annex I.

3.1.27

sample

all the data associated with a single time

Note 1 to entry: No two samples within a track can share the same decoding time; no two samples can share the same composition time.

Note 2 to entry: In non-hint tracks, a sample is, for example, an individual frame of video, a series of video frames in decoding order, or a compressed section of audio in decoding order; in hint tracks, a sample defines the formation of one or more streaming packets.

3.1.28

sample description

structure which defines and describes the format of some number of samples in a track

3.1.29

sample entry type

four-character code that is either a format value of a SampleEntry directly contained in SampleDescriptionBox or a data_format value of OriginalFormatBox

3.1.30

untransformed sample entry type

sample entry type of the track that would apply if no transformations had been performed to a transformed media track

Note 1 to entry: This is the sample entry type that would be the format value in a SampleEntry directly contained in the SampleDescriptionBox.

3.1.31

sample number

ordinal index number of a given sample where the first sample has sample number 1

3.1.32

sample table

packed directory for the timing and physical layout of the samples in a track

3.1.33

sync sample

sample in a track that starts at the ISAU of a SAP of type 1 or 2

Note 1 to entry: SAP types are defined in Annex I.

Note 2 to entry: Informally, a media sample that starts a new independent sequence of samples; if decoding starts at the sync sample, it and succeeding samples in decoding order can all be correctly decoded, and the resulting set of decoded samples forms the correct presentation of the media starting at the decoded sample that has the earliest composition time; a media format may provide a more precise definition of a sync sample for that format.

3.1.34

segment

portion of movie file, consisting of either (a) a MovieBox, with its associated media data (if any) and other associated boxes or (b) one or more MovieFragmentBoxes, with their associated media data, and other associated boxes

Note 1 to entry: The associated media data can be found by following byte offsets, but the process of finding associated boxes is not given in this standard and may be derived by other specifications.

3.1.35

segment file

ISO base media file containing one or more segment(s)

3.1.36

subsegment

time interval of a segment formed from MovieFragmentBoxes, that is also a valid segment

3.1.37

thumbnail image

smaller-resolution representation of an image

3.1.38

top-level box

box contained at file level

3.1.39

track

timed sequence of related samples (q.v.) in an ISO base media file

Note 1 to entry: For media data, a track corresponds to a sequence of images or sampled audio; for hint tracks, a track corresponds to a streaming channel.