Information technology — High efficiency coding and media delivery in heterogeneous environments — Part 12: Image File Format — Amendment 1: Support for predictive image coding, bursts, bracketing and other improvements

Technologies de l'information — Codage à haute efficacité et livraison des medias dans des environnements hétérogènes — Partie 12: Format de fichier d'image — Amendement 1: Support pour le codage prédictif des images, les rafales, le bracketing et autres améliorations

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INTERNATIONAL ISO/IEC
STANDARD 23008-12
First edition
2017-12
AMENDMENT 1
2020-11
Information technology — High
efficiency coding and media delivery
in heterogeneous environments —
Part 12:
Image File Format
AMENDMENT 1: Support for predictive
image coding, bursts, bracketing and
other improvements
Technologies de l'information — Codage à haute efficacité et livraison
des medias dans des environnements hétérogènes —
Partie 12: Format de fichier d'image
AMENDEMENT 1: Support pour le codage prédictif des images, les
rafales, le bracketing et autres améliorations
Reference number
ISO/IEC 23008-12:2017/Amd.1:2020(E)
ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 23008-12:2017/Amd.1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that

are members of ISO or IEC participate in the development of International Standards through

technical committees established by the respective organization to deal with particular fields of

technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other

international organizations, governmental and non-governmental, in liaison with ISO and IEC, also

take part in the work.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for

the different types of document should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent

rights. Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC

list of patent declarations received (see http:// patents .iec .ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.

A list of all parts in the ISO/IEC 23008 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO/IEC 2020 – All rights reserved iii
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
Information technology — High efficiency coding and
media delivery in heterogeneous environments —
Part 12:
Image File Format
AMENDMENT 1: Support for predictive image coding, bursts,
bracketing and other improvements
Clause 3
Add the following terms and definitions at the end of 3.1:
3.1.40
predictively coded image item

image item (3.1.17) that has a decoding dependency to one or more other coded image items (3.1.5)

3.1.41
unique ID

identifier for either an item, an entity group or a track that fulfils the requirements of the 'unif' brand

Note 1 to entry: Requirements on the 'unif' brand are specified in ISO/IEC 14496-12.

3.1.42
visual context

visual rendering surface such as a screen buffer, which may already contain visual material, and onto

which an image (3.1.15) can be rendered
Clause 4, item a)
Replace the text in item a) with the following:

a) the storage of a single coded image or a collection of coded images, possibly with derived images;

coded images are normally independently coded except when the 'pred' brand is signalled. In

such latter case, coded images may be independently coded or may have been coded with inter

prediction;
Clause 4, third paragraph:
Replace the third paragraph with the following:

In general, the single image support is used for simpler cases, particularly when neither timing nor

coding dependency is required. If advisory timing or other tools from the ISO base media file format

available for tracks are needed (e.g. sample grouping), then the second approach is needed.

© ISO/IEC 2020 – All rights reserved 1
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.4
Add the following new subclause after subclause 6.4.8:
6.4.9 Predictively coded image items

Predictively coded image items have a decoding dependency to one or more other coded image items.

An example for such an image item could be a P frame stored as an image item in a burst entity group

that has IPPP… structure, with the P frames dependent only on the preceding I frames.

Capability to have predictively coded image items has certain benefits especially in content re-editing

and cover image selection:
— Image sequences can be converted to image items with no transcoding.

— Any sample of an image sequence track can be selected as a cover image. The cover image does not

need to be intra-coded.

— Devices that do not have a video or image encoder are capable of updating the cover image of a file

containing an image sequence track.

— Storage efficiency is further achieved by re-using the predictively coded picture rather than re-

encoding it as I frame and storing as an additional image item. Moreover, image quality degradation

is also avoided.

— Re-encoding might not be allowed or preferred by the copyright owner. Predictively coded image

items avoid the need of re-encoding of any image from an image sequence track.

Predictively coded image items are linked to the coded image items they directly and indirectly depend

on by item references of type 'pred'. The list of referenced items in item references of type 'pred'

shall indicate the decoding order. When concatenated, the encoded media data of items with item_ID

equal to to_item_ID for all values of j from 0 to reference_count − 1, inclusive, in increasing order of

j, followed by the item with item_ID equal to from_item_ID shall form a bitstream that conforms to the

decoder configuration item property of the predictively coded image item.

In order to decode the predictively coded image item, there shall be no other decoding dependencies

other than the image items referenced by item references of type 'pred'.

The predictively coded image item shall be associated with exactly one RequiredReferenceTypesProperty

containing one reference type with the value 'pred'.
6.5.1
Add the following paragraphs at the end of the subclause 6.5.1, after the NOTE:

When unique IDs are used, an item_ID value in the ItemPropertyAssociationBox is resolved to an item

identifier whenever the embedding MetaBox contains an item with such identifier, and is resolved to an

entity group identifier otherwise.

Properties may be associated with an entity group, but only when explicitly stated in their specification.

In such case, properties apply to the entity group as a whole, and not individually to each entity within

the group.
2 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5
Add the following new subclauses after subclause 6.5.12:
6.5.13 Image scaling
6.5.13.1 Definition
'iscl'
Box type:
Property type: Transformative item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one
The image scaling 'iscl' transformative item property scales an input image.

The input image is the output of the previous transformative item property, if any, or the reconstructed

image of the associated image item.

The width and height of the input image (call those input_width and input_height) are resized to a

target width and height, in pixels, respectively equal to ceil( (input_width * target_width_numerator)

/ target_width_denominator) and ceil((input_height * target_height_numerator) / target_height_

denominator), where ceil() is the ceiling function. The scaling of the input image applies to both width

and height separately. The fraction may or may not be in reduced terms.
NOTE 1 Formulas above use a floating-point division, not an integer division.

NOTE 2 When the input image is the reconstructed image of the associated image item, input_

width and input_height, respectively, are equal to image_width and image_height declared in the

ImageSpatialExtentsProperty associated with this image item. Otherwise, input_width and input_height

are equal to the width and height of the output of the previous transformative item property.

6.5.13.2 Syntax
aligned(8) class ImageScaling
extends ItemFullProperty('iscl', version = 0, flags = 0) {
unsigned int (16) target_width_numerator;
unsigned int (16) target_width_denominator;
unsigned int (16) target_height_numerator;
unsigned int (16) target_height_denominator;
6.5.13.3 Semantics

target_width_numerator specifies the numerator of the scaling ratio for the resized image in the

horizontal dimension. The value 0 shall not be used.

target_width_denominator specifies the denominator of the scaling ratio for the resized image in the

horizontal dimension. The value 0 shall not be used.

target_height_numerator specifies the numerator of the scaling ratio for the resized image in the

vertical dimension. The value 0 shall not be used.

target_height_denominator specifies the denominator of the scaling ratio for the resized image in the

vertical dimension. The value 0 shall not be used.
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.14 Content light level
6.5.14.1 Definition
'clli'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The content light level item property provides information about the light level in the content.

6.5.14.2 Syntax

The content light level 'clli' descriptive item property has the same syntax as the ContentLightLevelBox

as defined in ISO/IEC 14496-12.
6.5.14.3 Semantics

The semantics of the syntax elements within the content light level 'clli' item property are the same

as those specified for the syntax elements of ContentLightLevelBox as defined in ISO/IEC 14496-12.

6.5.15 Mastering display colour volume
6.5.15.1 Definition
'mdcv'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

This property provides information about the colour primaries, white point, and mastering luminance

in the content.
6.5.15.2 Syntax

This property has the same syntax as the MasteringDisplayColourVolumeBox as defined in

ISO/IEC 14496-12.
6.5.15.3 Semantics

The semantics of the syntax elements within this property are the same as those specified for the

syntax elements of MasteringDisplayColourVolumeBox as defined in ISO/IEC 14496-12.

4 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.16 Content colour volume
6.5.16.1 Definition
'cclv'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

This property describes the colour volume characteristics of the associated pictures.

6.5.16.2 Syntax

This property has the same syntax as the ContentColourVolumeBox as defined in ISO/IEC 14496-12.

6.5.16.3 Semantics

The semantics of the syntax elements within this property are the same as those specified for the

syntax elements of ContentColourVolumeBox as defined in ISO/IEC 14496-12.
6.5.17 Required reference types
6.5.17.1 Definition
'rref'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): Yes, for a predictively coded image item. No, otherwise.
Quantity (per item): At most one

The RequiredReferenceTypesProperty descriptive item property lists the item reference types that a

reader shall understand and process to decode the associated image item. The respective essential

flag shall be equal to 1 in ItemPropertyAssociationBox.

NOTE In the absence of this property, required reference types are not explicitly listed, but can still exist.

6.5.17.2 Syntax
aligned(8) class RequiredReferenceTypesProperty
extends ItemFullProperty('rref', version = 0, flags = 0){
unsigned int(8) reference_type_count;
for (i=0; i< reference_type_count; i++) {
unsigned int(32) reference_type[i];
6.5.17.3 Semantics

reference_type_count indicates the number of reference types that are required to understand and

process to decode the associated image item.

reference_type[i] indicates a reference type that is required to understand and process to decode the

associated image item.
© ISO/IEC 2020 – All rights reserved 5
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.18 Creation time information
6.5.18.1 Definition
'crtt'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The CreationTimeProperty documents the creation time of the associated item or group of entities.

6.5.18.2 Syntax
aligned(8) class CreationTimeProperty
extends ItemFullProperty('crtt', version = 0, flags = 0) {
unsigned int(64) creation_time;
6.5.18.3 Semantics

creation_time is an integer that declares the creation time of the item or group of entities (in

microseconds since midnight, Jan. 1, 1904, in UTC time).
6.5.19 Modification time information
6.5.19.1 Definition
'mdft'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The ModificationTimeProperty documents the last modification time of the associated item or group

of entities.
6.5.19.2 Syntax
aligned(8) class ModificationTimeProperty
extends ItemFullProperty('mdft', version = 0, flags = 0) {
unsigned int(64) modification_time;
6.5.19.3 Semantics

modification_time is an integer that declares the most recent time the item or group of entities was

modified (in microseconds since midnight, Jan. 1, 1904, in UTC time).
6 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.20 User description
6.5.20.1 Definition
'udes'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): Zero or more

The UserDescriptionProperty permits the association of item(s) or entity group(s) with a user-

defined name, description and tags; there may be multiple such properties, which shall have different

language codes.

When several instances of UserDescriptionProperty are associated with the same item or entity group,

they represent alternatives possibly expressed in different languages and a reader should choose the

most appropriate. At most one UserDescriptionProperty with the same alt_lang value should apply to

the same item or entity group.
6.5.20.2 Syntax
aligned(8) class UserDescriptionProperty
extends ItemFullProperty('udes', version = 0, flags = 0){
utf8string lang;
utf8string name;
utf8string description;
utf8string tags;
6.5.20.3 Semantics

lang is a character string containing an IETF RFC 5646 compliant language tag string, such as "en-

US", "fr-FR", or "zh-CN“, representing the language of the text contained in name, description and tags.

When lang is empty, the language is unknown/undefined.

name is a null-terminated UTF-8 character string containing human readable name for the item or

group of entities. If not present (an empty string is supplied) no name is provided.

description is a null-terminated UTF-8 character string containing human readable description of the

item or group of entities. If not present (an empty string is supplied) no description is provided.

tags is a null-terminated UTF-8 character string containing comma-separated user-defined tags

related to the item(s). If not present (an empty string is supplied) no tags is provided.

6.5.21 Accessibility text
6.5.21.1 Definition
'altt'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per an item): No
Quantity (per an item): Zero or more
© ISO/IEC 2020 – All rights reserved 7
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ISO/IEC 23008-12:2017/Amd.1:2020(E)

The AccessibilityTextProperty contains a string suitable to be used as an alternate text for an image

if the image cannot be displayed, similarly to alt text in HTML. The language used by the alternate text

is represented by a language tag string compliant with IETF RFC 5646.

When several instances of AccessibilityTextProperty are associated with the same item, they

represent alternatives possibly expressed in different languages and a reader should choose the most

appropriate. At most one AccessibilityTextProperty with the same alt_lang value should apply to

the same item.
6.5.21.2 Syntax
aligned(8) class AccessibilityTextProperty
extends ItemFullProperty('altt', version = 0, flags = 0) {
utf8string alt_text;
utf8string alt_lang;
6.5.21.3 Semantics

alt_text is a character string suitable to be used as an alternate text for an image if the image cannot

be displayed, similarly to alt text in HTML.

alt_lang is a character string containing an IETF RFC 5646 compliant language tag string, such as "en-

US", "fr-FR", or "zh-CN“, representing the language of the text contained in alt_text. When alt_lang is

empty, the language is unknown/undefined.
6.5.22 Auto Exposure Information
6.5.22.1 Definition
'aebr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The auto exposure descriptive item property defines the exposure variation of the associated image

item relatively to the camera settings.

It is used to specify the properties of an image item included in an 'aebr' entity group as specified in

subclause 6.8.6.
6.5.22.2 Syntax
aligned(8) class AutoExposureProperty
extends ItemFullProperty('aebr', version = 0, flags = 0) {
int(8) exposure_step;
int(8) exposure_numerator;
6.5.22.3 Semantics

exposure_step is an integer value that specifies the increment steps used during the exposure

bracketing. When equals to 1, a full stop increment is used, when equals to 2, a half stop increment is

used, when equals to 3, a third stop increment is used, and when equals to 4, a quarter stop increment is

used. Other values are reserved.

exposure_numerator is an integer value specifying the exposure numerator used to compute the

exposure value stop of the item.
8 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)

The exposure value variation of the associated image item compared to the camera settings is expressed

as a number of stops, and is computed as exposure_numerator/exposure_step.
6.5.23 White balance information
6.5.23.1 Definition
'wbbr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The white balance descriptive item property defines the white balance compensation on blue/amber

bias and/or magenta/green bias applied to the associated image item relatively to the camera settings.

It is used to specify the properties of an image item included in a 'wbbr' entity group as specified in

subclause 6.8.6.
6.5.23.2 Syntax
aligned(8) class WhiteBalanceProperty
extends ItemFullProperty('wbbr', version = 0, flags = 0) {
unsigned int(16) blue_amber;
int(8) green_magenta;
6.5.23.3 Semantics

blue_amber is an unsigned integer indicating the colour temperature component of the white balance

in Kelvin.

green_magenta is a signed integer indicating the colour deviation component of white balance in unit of

1/100 Duv (distance to the blackbody locus).

NOTE A Duv of 0 indicates a light source that is neutral. A negative Duv indicates a magenta colour shift,

while a positive Duv indicates a green colour shift.
6.5.24 Focus information
6.5.24.1 Definition
'fobr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The focus descriptive item property defines the focus variation of the associated image item relatively

to the camera settings.

It is used to specify the properties of an image item included in an 'fobr' entity group as specified in

subclause 6.8.6.
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.24.2 Syntax
aligned(8) class FocusProperty
extends ItemFullProperty('fobr', version = 0, flags = 0) {
unsigned int(16) focus_distance_numerator;
unsigned int(16) focus_distance_denominator;
6.5.24.3 Semantics

The focus distance is expressed in meter as the ratio of focus_distance_numerator and focus_distance_

denominator. Focus at infinity is expressed as division by zero, i.e. focus_distance_denominator is

equal to 0 and focus_distance_numerator should be equal to 0.
6.5.25 Flash exposure information
6.5.25.1 Definition
'afbr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The flash exposure descriptive item property defines the flash exposure variation of the associated

image item relatively to the camera settings.

It is used to specify the properties of an image item included in an 'afbr' entity group as specified in

subclause 6.8.6.
6.5.25.2 Syntax
aligned(8) class FlashExposureProperty
extends ItemFullProperty('afbr', version = 0, flags = 0) {
int(8) flash_exposure_numerator;
int(8) flash_exposure_denominator;
6.5.25.3 Semantics

flash_exposure_numerator and flash_exposure_denominator are integers representing the flash

exposure value of the sample expressed in a number of f-stops as the ratio of flash_exposure_numerator

and flash_exposure_denominator.
6.5.26 Depth of field information
6.5.26.1 Definition
'dobr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The depth of field descriptive item property defines the depth of field variation of the associated image

item relatively to the camera settings. It is expressed as an aperture change.

It is used to specify the properties of an image item included in a 'dobr' entity group as specified in

subclause 6.8.6.
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.5.26.2 Syntax
aligned(8) class DepthOfFieldProperty
extends ItemFullProperty('dobr', version = 0, flags = 0) {
int(8) f_stop_numerator;
int(8) f_stop_denominator;
6.5.26.3 Semantics

The depth of field variation is expressed as an aperture change in a number of stops, and is computed

as f_stop_numerator/f_stop_denominator.
6.5.27 Panorama information
6.5.27.1 Definition
'pano'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The panorama descriptive item property defines the characteristics associated with a panorama

defined by a 'pano' entity group.

This item property should only be associated with an entity group with grouping_type equal to 'pano'.

6.5.27.2 Syntax
aligned(8) class PanoramaProperty
extends ItemFullProperty('pano', version = 0, flags = 0) {
unsigned int(8) panorama_direction;
if (panorama_direction >= 4 && panorama_direction <= 5) { // grid
unsigned int(8) rows_minus_one;
unsigned int(8) columns_minus_one;
6.5.27.3 Semantics

panorama_direction is an unsigned integer signalling the type of panorama used and the scanning

order of input images in the panorama:
— 0: left-to-right horizontal panorama
— 1: right-to-left horizontal panorama
— 2: bottom-to-top vertical panorama
— 3: top-to-bottom vertical panorama

— 4: grid panorama in raster scan order, i.e. rows and columns are organised from left-to-right and

top-to-bottom starting from the top-left corner.

— 5: grid panorama in continuous order, i.e. starting from the top-left corner, the first row is organized

from left-to-right, then the second row is organised from right-to-left, the third row is organized

from left-to-right and so on.
other values are undefined.
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ISO/IEC 23008-12:2017/Amd.1:2020(E)

rows_minus_one is an unsigned integer that specifies the number of rows in the grid minus one.

columns_minus_one is an unsigned integer that specifies the number of columns in the grid minus one.

6.6.2.3
Replace the text in NOTE 1 with the following:

NOTE 1 If the desired input images are not of a consistent size, then derived image items that scale or crop

them, as needed to make them consistent, can be used; other specifications can, however, restrict whether

derived image items are permissible as input to the image grid derived image item. This document specifies

cropping in 6.5.8 and scaling in subclause 6.5.13.
6.8
Rename the heading of subclause 6.8 as “Entity and sample groups”.

Move the current subclause 6.8 “Relating an untimed item to a timed sequence" and all of its subclauses

to subclause 6.8.1. Add the following new subclause 6.8.2 at the end of the subclause:

6.8.2 Burst images
6.8.2.1 Overview

Burst images are a series of rapid succession images. Burst images can contain any number of images

and may benefit fully from the image sensor resolution or image processing pipeline, hence providing

access to high-resolution original versions of individual images of a burst capture.

An image burst may be stored as an image sequence track or a set of image items. The latter enables

flexible and advanced burst image storage and retrieval use cases such as storage of individual burst

images as derived image items.
6.8.2.2 'brst' entity group

The burst image entity group ('brst') indicates a set of images that form a temporal burst image

set. The entity_id values of the image items in a 'brst' entity group shall be listed in a temporally

increasing order.

When an image sequence track is included in a 'brst' entity group, there shall be only one entity_id

present in the 'brst' entity group. An image sequence track may be included in a 'brst' entity group

to indicate that it contains a burst-captured image sequence as opposed to other types of multi-image

captures, such as focal or exposure stacks.

There may be multiple 'brst' entity groupings in the same file with different group_id values.

6.8.3 'tsyn' entity group

A time-synchronized capture entity group ('tsyn') contains entities that were synchronously captured.

A single 'tsyn' entity group shall include entity_id values that either resolve to image items or to

image sequence tracks, but not a mixture of both. A 'tsyn' entity group including image items indicates

that the image items were simultaneously captured spanning the same time. A 'tsyn' entity group

including image sequence tracks indicates that all tracks in the group, if played using the timing in the

file, are in sync.
Tracks included in the same 'tsyn' entity group shall have the same duration.

There may be multiple 'tsyn' entity groupings in the same file with different group_id values.

12 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/Amd.1:2020(E)
6.8.4 'iaug' entity group

An 'iaug' entity group associates an image item with an audio track. When displaying an image item

mapped to an 'iaug' entity group, a reader should also play the related audio track provided that audio

playback is enabled e.g. based on user preferences.

The number of entities in an 'iaug' entity group shall be exactly 2, one of the entity_id values shall

indi
...

FINAL
ISO/IEC
AMENDMENT
DRAFT
23008-12:2017
FDAM 2
ISO/IEC JTC 1/SC 29
Information technology — High
Secretariat: JISC
efficiency coding and media delivery
Voting begins on:
2020-09-01 in heterogeneous environments —
Voting terminates on:
Part 12:
2020-10-27
Image File Format
AMENDMENT 2: Support for predictive
image coding, bursts, bracketing and
other improvements
Technologies de l'information — Codage à haute efficacité et livraison
des medias dans des environnements hétérogènes —
Partie 12: Format de fichier d'image
AMENDEMENT 2
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/IEC 23008-12:2017/FDAM 2:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO/IEC 2020
---------------------- Page: 1 ----------------------
ISO/IEC 23008-12:2017/FDAM 2:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
Foreword

ISO (the International Organization for Standardization) and IEC (the International Electrotechnical

Commission) form the specialized system for worldwide standardization. National bodies that

are members of ISO or IEC participate in the development of International Standards through

technical committees established by the respective organization to deal with particular fields of

technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other

international organizations, governmental and non-governmental, in liaison with ISO and IEC, also

take part in the work.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for

the different types of document should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject

of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent

rights. Details of any patent rights identified during the development of the document will be in the

Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC

list of patent declarations received (see http:// patents .iec .ch).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,

Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information.

A list of all parts in the ISO/IEC 23008 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO/IEC 2020 – All rights reserved iii
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
Information technology — High efficiency coding and
media delivery in heterogeneous environments —
Part 12:
Image File Format
AMENDMENT 2: Support for predictive image coding, bursts,
bracketing and other improvements
Clause 3
Add the following terms and definitions at the end of 3.1:
3.1.40
predictively coded image item

image item (3.1.17) that has a decoding dependency to one or more other coded image items (3.1.5)

3.1.41
unique ID

identifier for either an item, an entity group or a track that fulfils the requirements of the 'unif' brand

Note 1 to entry: Requirements on the 'unif' brand are specified in ISO/IEC 14496-12.

3.1.42
visual context

visual rendering surface such as a screen buffer, which may already contain visual material, and onto

which an image (3.1.15) can be rendered
Clause 4, item a)
Replace the text in item a) with the following:

a) the storage of a single coded image or a collection of coded images, possibly with derived images;

coded images are normally independently coded except when the 'pred' brand is signalled. In

such latter case, coded images may be independently coded or may have been coded with inter

prediction;
Clause 4, third paragraph:
Replace the third paragraph with the following:

In general, the single image support is used for simpler cases, particularly when neither timing nor

coding dependency is required. If advisory timing or other tools from the ISO base media file format

available for tracks are needed (e.g. sample grouping), then the second approach is needed.

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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.4
Add the following new subclause after subclause 6.4.8:
6.4.9 Predictively coded image items

Predictively coded image items have a decoding dependency to one or more other coded image items.

An example for such an image item could be a P frame stored as an image item in a burst entity group

that has IPPP… structure, with the P frames dependent only on the preceding I frames.

Capability to have predictively coded image items has certain benefits especially in content re-editing

and cover image selection:
— Image sequences can be converted to image items with no transcoding.

— Any sample of an image sequence track can be selected as a cover image. The cover image does not

need to be intra-coded.

— Devices that do not have a video or image encoder are capable of updating the cover image of a file

containing an image sequence track.

— Storage efficiency is further achieved by re-using the predictively coded picture rather than re-

encoding it as I frame and storing as an additional image item. Moreover, image quality degradation

is also avoided.

— Re-encoding might not be allowed or preferred by the copyright owner. Predictively coded image

items avoid the need of re-encoding of any image from an image sequence track.

Predictively coded image items are linked to the coded image items they directly and indirectly depend

on by item references of type 'pred'. The list of referenced items in item references of type 'pred'

shall indicate the decoding order. When concatenated, the encoded media data of items with item_ID

equal to to_item_ID for all values of j from 0 to reference_count − 1, inclusive, in increasing order of

j, followed by the item with item_ID equal to from_item_ID shall form a bitstream that conforms to the

decoder configuration item property of the predictively coded image item.

In order to decode the predictively coded image item, there shall be no other decoding dependencies

other than the image items referenced by item references of type 'pred'.

The predictively coded image item shall be associated with exactly one RequiredReferenceTypesProperty

containing one reference type with the value 'pred'.
6.5.1
Add the following paragraphs at the end of the subclause 6.5.1, after the NOTE:

When unique IDs are used, an item_ID value in the ItemPropertyAssociationBox is resolved to an item

identifier whenever the embedding MetaBox contains an item with such identifier, and is resolved to an

entity group identifier otherwise.

Properties may be associated with an entity group, but only when explicitly stated in their specification.

In such case, properties apply to the entity group as a whole, and not individually to each entity within

the group.
2 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5
Add the following new subclauses after subclause 6.5.12:
6.5.13 Image scaling
6.5.13.1 Definition
'iscl'
Box type:
Property type: Transformative item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one
The image scaling 'iscl' transformative item property scales an input image.

The input image is the output of the previous transformative item property, if any, or the reconstructed

image of the associated image item.

The width and height of the input image (call those input_width and input_height) are resized to a

target width and height, in pixels, respectively equal to ceil( (input_width * target_width_numerator)

/ target_width_denominator) and ceil((input_height * target_height_numerator) / target_height_

denominator), where ceil() is the ceiling function. The scaling of the input image applies to both width

and height separately. The fraction may or may not be in reduced terms.
NOTE 1 Formulas above use a floating-point division, not an integer division.

NOTE 2 When the input image is the reconstructed image of the associated image item, input_

width and input_height, respectively, are equal to image_width and image_height declared in the

ImageSpatialExtentsProperty associated with this image item. Otherwise, input_width and input_height

are equal to the width and height of the output of the previous transformative item property.

6.5.13.2 Syntax
aligned(8) class ImageScaling
extends ItemFullProperty('iscl', version = 0, flags = 0) {
unsigned int (16) target_width_numerator;
unsigned int (16) target_width_denominator;
unsigned int (16) target_height_numerator;
unsigned int (16) target_height_denominator;
6.5.13.3 Semantics

target_width_numerator specifies the numerator of the scaling ratio for the resized image in the

horizontal dimension. The value 0 shall not be used.

target_width_denominator specifies the denominator of the scaling ratio for the resized image in the

horizontal dimension. The value 0 shall not be used.

target_height_numerator specifies the numerator of the scaling ratio for the resized image in the

vertical dimension. The value 0 shall not be used.

target_height_denominator specifies the denominator of the scaling ratio for the resized image in the

vertical dimension. The value 0 shall not be used.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.14 Content light level
6.5.14.1 Definition
'clli'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The content light level item property provides information about the light level in the content.

6.5.14.2 Syntax

The content light level 'clli' descriptive item property has the same syntax as the ContentLightLevelBox

as defined in ISO/IEC 14496-12.
6.5.14.3 Semantics

The semantics of the syntax elements within the content light level 'clli' item property are the same

as those specified for the syntax elements of ContentLightLevelBox as defined in ISO/IEC 14496-12.

6.5.15 Mastering display colour volume
6.5.15.1 Definition
'mdcv'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

This property provides information about the colour primaries, white point, and mastering luminance

in the content.
6.5.15.2 Syntax

This property has the same syntax as the MasteringDisplayColourVolumeBox as defined in

ISO/IEC 14496-12.
6.5.15.3 Semantics

The semantics of the syntax elements within this property are the same as those specified for the

syntax elements of MasteringDisplayColourVolumeBox as defined in ISO/IEC 14496-12.

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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.16 Content colour volume
6.5.16.1 Definition
'cclv'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

This property describes the colour volume characteristics of the associated pictures.

6.5.16.2 Syntax

This property has the same syntax as the ContentColourVolumeBox as defined in ISO/IEC 14496-12.

6.5.16.3 Semantics

The semantics of the syntax elements within this property are the same as those specified for the

syntax elements of ContentColourVolumeBox as defined in ISO/IEC 14496-12.
6.5.17 Required reference types
6.5.17.1 Definition
'rref'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): Yes, for a predictively coded image item. No, otherwise.
Quantity (per item): At most one

The RequiredReferenceTypesProperty descriptive item property lists the item reference types that a

reader shall understand and process to decode the associated image item. The respective essential

flag shall be equal to 1 in ItemPropertyAssociationBox.

NOTE In the absence of this property, required reference types are not explicitly listed, but can still exist.

6.5.17.2 Syntax
aligned(8) class RequiredReferenceTypesProperty
extends ItemFullProperty('rref', version = 0, flags = 0){
unsigned int(8) reference_type_count;
for (i=0; i< reference_type_count; i++) {
unsigned int(32) reference_type[i];
6.5.17.3 Semantics

reference_type_count indicates the number of reference types that are required to understand and

process to decode the associated image item.

reference_type[i] indicates a reference type that is required to understand and process to decode the

associated image item.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.18 Creation time information
6.5.18.1 Definition
'crtt'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The CreationTimeProperty documents the creation time of the associated item or group of entities.

6.5.18.2 Syntax
aligned(8) class CreationTimeProperty
extends ItemFullProperty('crtt', version = 0, flags = 0) {
unsigned int(64) creation_time;
6.5.18.3 Semantics

creation_time is an integer that declares the creation time of the item or group of entities (in

microseconds since midnight, Jan. 1, 1904, in UTC time).
6.5.19 Modification time information
6.5.19.1 Definition
'mdft'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The ModificationTimeProperty documents the last modification time of the associated item or group

of entities.
6.5.19.2 Syntax
aligned(8) class ModificationTimeProperty
extends ItemFullProperty('mdft', version = 0, flags = 0) {
unsigned int(64) modification_time;
6.5.19.3 Semantics

modification_time is an integer that declares the most recent time the item or group of entities was

modified (in microseconds since midnight, Jan. 1, 1904, in UTC time).
6 © ISO/IEC 2020 – All rights reserved
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.20 User description
6.5.20.1 Definition
'udes'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): Zero or more

The UserDescriptionProperty permits the association of item(s) or entity group(s) with a user-

defined name, description and tags; there may be multiple such properties, which shall have different

language codes.

When several instances of UserDescriptionProperty are associated with the same item or entity group,

they represent alternatives possibly expressed in different languages and a reader should choose the

most appropriate. At most one UserDescriptionProperty with the same alt_lang value should apply to

the same item or entity group.
6.5.20.2 Syntax
aligned(8) class UserDescriptionProperty
extends ItemFullProperty('udes', version = 0, flags = 0){
utf8string lang;
utf8string name;
utf8string description;
utf8string tags;
6.5.20.3 Semantics

lang is a character string containing an IETF RFC 5646 compliant language tag string, such as "en-

US", "fr-FR", or "zh-CN“, representing the language of the text contained in name, description and tags.

When lang is empty, the language is unknown/undefined.

name is a null-terminated UTF-8 character string containing human readable name for the item or

group of entities. If not present (an empty string is supplied) no name is provided.

description is a null-terminated UTF-8 character string containing human readable description of the

item or group of entities. If not present (an empty string is supplied) no description is provided.

tags is a null-terminated UTF-8 character string containing comma-separated user-defined tags

related to the item(s). If not present (an empty string is supplied) no tags is provided.

6.5.21 Accessibility text
6.5.21.1 Definition
'altt'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per an item): No
Quantity (per an item): Zero or more
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)

The AccessibilityTextProperty contains a string suitable to be used as an alternate text for an image

if the image cannot be displayed, similarly to alt text in HTML. The language used by the alternate text

is represented by a language tag string compliant with IETF RFC 5646.

When several instances of AccessibilityTextProperty are associated with the same item, they

represent alternatives possibly expressed in different languages and a reader should choose the most

appropriate. At most one AccessibilityTextProperty with the same alt_lang value should apply to

the same item.
6.5.21.2 Syntax
aligned(8) class AccessibilityTextProperty
extends ItemFullProperty('altt', version = 0, flags = 0) {
utf8string alt_text;
utf8string alt_lang;
6.5.21.3 Semantics

alt_text is a character string suitable to be used as an alternate text for an image if the image cannot

be displayed, similarly to alt text in HTML.

alt_lang is a character string containing an IETF RFC 5646 compliant language tag string, such as "en-

US", "fr-FR", or "zh-CN“, representing the language of the text contained in alt_text. When alt_lang is

empty, the language is unknown/undefined.
6.5.22 Auto Exposure Information
6.5.22.1 Definition
'aebr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The auto exposure descriptive item property defines the exposure variation of the associated image

item relatively to the camera settings.

It is used to specify the properties of an image item included in an 'aebr' entity group as specified in

subclause 6.8.6.
6.5.22.2 Syntax
aligned(8) class AutoExposureProperty
extends ItemFullProperty('aebr', version = 0, flags = 0) {
int(8) exposure_step;
int(8) exposure_numerator;
6.5.22.3 Semantics

exposure_step is an integer value that specifies the increment steps used during the exposure

bracketing. When equals to 1, a full stop increment is used, when equals to 2, a half stop increment is

used, when equals to 3, a third stop increment is used, and when equals to 4, a quarter stop increment is

used. Other values are reserved.

exposure_numerator is an integer value specifying the exposure numerator used to compute the

exposure value stop of the item.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)

The exposure value variation of the associated image item compared to the camera settings is expressed

as a number of stops, and is computed as exposure_numerator/exposure_step.
6.5.23 White balance information
6.5.23.1 Definition
'wbbr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The white balance descriptive item property defines the white balance compensation on blue/amber

bias and/or magenta/green bias applied to the associated image item relatively to the camera settings.

It is used to specify the properties of an image item included in a 'wbbr' entity group as specified in

subclause 6.8.6.
6.5.23.2 Syntax
aligned(8) class WhiteBalanceProperty
extends ItemFullProperty('wbbr', version = 0, flags = 0) {
unsigned int(16) blue_amber;
int(8) green_magenta;
6.5.23.3 Semantics

blue_amber is an unsigned integer indicating the colour temperature component of the white balance

in Kelvin.

green_magenta is a signed integer indicating the colour deviation component of white balance in unit of

1/100 Duv (distance to the blackbody locus).

NOTE A Duv of 0 indicates a light source that is neutral. A negative Duv indicates a magenta colour shift,

while a positive Duv indicates a green colour shift.
6.5.24 Focus information
6.5.24.1 Definition
'fobr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The focus descriptive item property defines the focus variation of the associated image item relatively

to the camera settings.

It is used to specify the properties of an image item included in an 'fobr' entity group as specified in

subclause 6.8.6.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.24.2 Syntax
aligned(8) class FocusProperty
extends ItemFullProperty('fobr', version = 0, flags = 0) {
unsigned int(16) focus_distance_numerator;
unsigned int(16) focus_distance_denominator;
6.5.24.3 Semantics

The focus distance is expressed in meter as the ratio of focus_distance_numerator and focus_distance_

denominator. Focus at infinity is expressed as division by zero, i.e. focus_distance_denominator is

equal to 0 and focus_distance_numerator should be equal to 0.
6.5.25 Flash exposure information
6.5.25.1 Definition
'afbr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The flash exposure descriptive item property defines the flash exposure variation of the associated

image item relatively to the camera settings.

It is used to specify the properties of an image item included in an 'afbr' entity group as specified in

subclause 6.8.6.
6.5.25.2 Syntax
aligned(8) class FlashExposureProperty
extends ItemFullProperty('afbr', version = 0, flags = 0) {
int(8) flash_exposure_numerator;
int(8) flash_exposure_denominator;
6.5.25.3 Semantics

flash_exposure_numerator and flash_exposure_denominator are integers representing the flash

exposure value of the sample expressed in a number of f-stops as the ratio of flash_exposure_numerator

and flash_exposure_denominator.
6.5.26 Depth of field information
6.5.26.1 Definition
'dobr'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per item): No
Quantity (per item): At most one

The depth of field descriptive item property defines the depth of field variation of the associated image

item relatively to the camera settings. It is expressed as an aperture change.

It is used to specify the properties of an image item included in a 'dobr' entity group as specified in

subclause 6.8.6.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)
6.5.26.2 Syntax
aligned(8) class DepthOfFieldProperty
extends ItemFullProperty('dobr', version = 0, flags = 0) {
int(8) f_stop_numerator;
int(8) f_stop_denominator;
6.5.26.3 Semantics

The depth of field variation is expressed as an aperture change in a number of stops, and is computed

as f_stop_numerator/f_stop_denominator.
6.5.27 Panorama information
6.5.27.1 Definition
'pano'
Box type:
Property type: Descriptive item property
ItemPropertyContainerBox
Container:
Mandatory (per associated item_ID): No
Quantity (per associated item_ID): At most one

The panorama descriptive item property defines the characteristics associated with a panorama

defined by a 'pano' entity group.

This item property should only be associated with an entity group with grouping_type equal to 'pano'.

6.5.27.2 Syntax
aligned(8) class PanoramaProperty
extends ItemFullProperty('pano', version = 0, flags = 0) {
unsigned int(8) panorama_direction;
if (panorama_direction >= 4 && panorama_direction <= 5) { // grid
unsigned int(8) rows_minus_one;
unsigned int(8) columns_minus_one;
6.5.27.3 Semantics

panorama_direction is an unsigned integer signalling the type of panorama used and the scanning

order of input images in the panorama:
— 0: left-to-right horizontal panorama
— 1: right-to-left horizontal panorama
— 2: bottom-to-top vertical panorama
— 3: top-to-bottom vertical panorama

— 4: grid panorama in raster scan order, i.e. rows and columns are organised from left-to-right and

top-to-bottom starting from the top-left corner.

— 5: grid panorama in continuous order, i.e. starting from the top-left corner, the first row is organized

from left-to-right, then the second row is organised from right-to-left, the third row is organized

from left-to-right and so on.
other values are undefined.
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ISO/IEC 23008-12:2017/FDAM 2:2020(E)

rows_minus_one is an unsigned integer that specifies the number of rows in the grid minus one.

columns_minus_one is an unsigned integer that specifies the number of columns in the grid minus one.

6.6.2.3
Replace the text in NOTE 1 with the following:

NOTE 1 If the desired input images are not of a consistent size, then derived image items that scale or crop

them, as needed to make them consistent, can be used; other specifications can, however, restrict whether

derived image items are permissible as input to the image grid derived image item. This document specifies

cropping in 6.5.8 and scaling in subclause 6.5.13.
6.8
Rename the heading of subclause 6.8 as “Entity and sample groups”.

Move the current subclause 6.8 “Relating an untimed item to a timed sequence" and all of its subclauses

to subclause 6.8.1. Add the following new subclause 6.8.2 at the end of the subclause:

6.8.2 Burst images
6.8.2.1 Overview

Burst images are a series of rapid succession images. Burst images can contain any number of images

and may benefit fully from the image sensor resolution or image processing pipeline, hence providing

access to high-resolution original versions of individual images of a burst capture.

An image burst may be stored as an image sequence track or a set of image items. The latter enables

flexible and advanced burst image storage and retrieval use cases such as storage of individual burst

images as derived image items.
6.8.2.2 'brst' entity group

The burst image entity group ('brst') indicates a set of images that form a temporal burst image

set. The entity_id values of the image items in a 'brst' entity group shall be listed in a temporally

increasing order.

When an image sequence track is included in a 'brst' entity group, there shall be only one entity_id

present in the 'brst' entity group. An image sequence track may be included in a 'brst' entity group

to indicate that it contains a burst-captured image sequence as opposed to other types of multi-image

captures, such as focal or exposure stacks.

There may be multiple 'brst' entity groupings in the same file with different group_id values.

6.8.3 'tsyn' entity group

A time-synchronized capture entity group ('tsyn') contains entities that were synchronously captured.

A single 'tsyn' entity group shall include entity_id values that either resolve to image items or to

image sequence tracks, but not a mixture of both. A 'tsyn' entity group including image items indicates

that the image items were simultaneously captured spanning the same time. A 'tsyn' entity group

including image sequence tracks indicates that all tracks in the group, if played using the timing in the

file, are in sync.
Tracks included in the same 'tsyn' entity group shall have the same duration.

There may be multiple 'tsyn' entity groupings in the same file with different group_id values.

12 © ISO/IEC 2020 – All rights reserved
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