ISO/IEC 23090-31:2025

International
Standard
ISO/IEC 23090-31
First edition
Information technology — Coded
2025-01
representation of immersive media —
Part 31:
Haptics coding
Technologies de l'information — Représentation codée de média
immersifs —
Partie 31: Codage haptique
Reference number
© ISO/IEC 2025
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© ISO/IEC 2025 – All rights reserved
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions .1
3.2 Abbreviated terms .3
3.3 Mnemonics .4
4 Overview and architecture . 4
4.1 Overview .4
4.2 Codec architecture .4
5 Data model . 5
5.1 Data structure overview .5
5.2 Haptic experience .7
5.3 Haptic avatar .8
5.4 Haptic perception .9
5.5 Haptic device .11
5.6 Haptic channel . 12
5.6.1 General . 12
5.6.2 Custom mesh avatar . 13
5.6.3 Body part mask .14
5.6.4 Semantic body part and actuator mapping . 15
5.7 Haptic band .19
5.8 Haptic effect . 23
5.9 Haptic keyframe . 26
6 Interchange file format .27
6.1 Overview .27
6.2 HJIF Specifications . 28
6.2.1 MPEG_haptics . 28
6.2.2 MPEG_haptics.avatar . 29
6.2.3 MPEG_haptics.perception. 30
6.2.4 MPEG_haptics.sync .32
6.2.5 MPEG_haptics.reference_device .32
6.2.6 MPEG_haptics.channel . 33
6.2.7 MPEG_haptics.vector . 34
6.2.8 MPEG_haptics.band . 35
6.2.9 MPEG_haptics.effect . 36
6.2.10 MPEG_haptics.keyframe .37
7 MPEG-I haptic stream (MIHS) format .37
7.1 Overview .37
7.1.1 General .37
7.1.2 Initialization units . 39
7.1.3 Temporal and spatial units. 39
7.1.4 MIHS packets .41
7.2 Syntax and semantics .41
7.2.1 mpegiHapticStream() .41
7.2.2 mpegiHapticUnit() .42
7.2.3 mpegiHapticPacket().43
7.2.4 MIHSPacketPayload() . 44
7.2.5 readMetadataInitializationTiming() .45
7.2.6 readMetadataTiming() . 46
7.2.7 readMetadataExperience().47

© ISO/IEC 2025 – All rights reserved
iii
7.2.8 readAvatar() . 48
7.2.9 readMetadataPerception() . 48
7.2.10 readReferenceDevice() . 50
7.2.11 readMetadataChannel() . 53
7.2.12 readMetadataBand() . 55
7.2.13 readLibrary() . 56
7.2.14 readLibraryEffect() .57
7.2.15 readData() . 58
7.2.16 readEffect().59
7.2.17 readEffectBasis() . 63
7.2.18 readKeyframe() . 64
7.2.19 readTransientKeyframe() . 64
7.2.20 readCurveKeyframe() . 64
7.2.21 readVectorialKeyFrame() . 65
7.2.22 readWaveletEffect() . 65
7.2.23 readCRC() .67
7.3 Description of MIHSPacketType . 68
7.3.1 InitializationTiming . 68
7.3.2 Timing . 68
7.3.3 MetadataHaptics . 68
7.3.4 MetadataPerception . 69
7.3.5 MetadataChannel . 69
7.3.6 MetadataBand . .70
7.3.7 LibraryEffect .70
7.3.8 Data .71
7.3.9 CRC16 and CRC32 . 72
7.3.10 GlobalCRC16 and GlobalCRC32 . 72
7.4 Application examples . . 73
7.4.1 Initialization units . 73
7.4.2 Temporal and spatial units. 73
7.4.3 Silent units . 73
7.4.4 CRC packets .74
7.5 Random access support with MIHS (informative) .74
8 Processing model .75
8.1 Overview . 75
8.2 Encoder (informative) . 75
8.2.1 Encoder architecture . . 75
8.2.2 OHM metadata input file .76
8.2.3 Descriptive input files .76
8.2.4 PCM input file .76
8.2.5 Transcoding descriptive content . 77
8.2.6 Frequency band decomposition . 79
8.2.7 Keyframe extraction for low frequencies processing . 80
8.2.8 Wavelet encoding . 81
8.3 Decoder . 94
8.3.1 Decoder Architecture. 94
8.3.2 Metadata and parametric data decoding . 94
8.3.3 Wavelet Decoding . 94
8.3.4 Random access decode. 100
8.4 Synthesizer (informative) . . 100
Annex A (normative) JSON schema reference .103
Annex B (informative) OHM metadata input file format .104
Annex C (informative) Semantic body part and actuator mapping .106
Annex D (normative) Profiles and Levels .110
Bibliography .112

© ISO/IEC 2025 – All rights reserved
iv
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,
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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 or www.iec.ch/members_experts/refdocs).
ISO and IEC draw attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO and IEC take no position concerning the evidence, validity or applicability of any
claimed patent rights in respect thereof. As of the date of publication of this document, ISO and IEC had not
received notice of (a) patent(s) which may be required to implement this document. However, implementers
are cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents and https://patents.iec.ch. ISO and IEC shall not be held
responsible for identifying any or all such patent rights.
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.
In the IEC, see www.iec.ch/understanding-standards.
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 23090 series can be found on the ISO and IEC websites.
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 and
www.iec.ch/national-committees.

© ISO/IEC 2025 – All rights reserved
v
Introduction
Haptics provide an additional layer of entertainment and sensory immersion to the user. Therefore, the user
experience and enjoyment of media content, from a ISOBMFF files, broadcast channel, streaming games
or mobile advertisements can be significantly enhanced by the judicious addition of haptics to the audio/
video content. To that end, haptics has been proposed as a first-order media type, akin to audio and video, in
ISOBMFF. Further, haptics has also been proposed as an addition to ISO/IEC 23009-1 (MPEG-DASH) to signal
the presence of haptics in MP4 segments to DASH streaming clients. Lastly, the ISO/IEC 23090 (MPEG-I) use
cases have been augmented with haptics
Haptics digital encoding is the storing of tactile data in a digital format. As with audio and video, digital
encoding is of fundamental importance to allow digital haptic devices to function. Haptics encoding gained
relevance with the increased market importance of wideband haptics in consumer peripherals such as
smartphones with haptic engines and game consoles with haptic enabled controllers. The prior generation
of haptics peripherals was based on less expressive haptic actuators usually based on state machine control
processes.
In the field of haptics, the signal encoding usually takes one of two approaches:
— Quantized: This representation is generally made from measured data. The samples from the original
phenomenon are stored at a specific acquisition frequency inside the file to represent this signal. One
example of a quantized haptic signal is proposed through WAV files, originally developed for audio. WAV
file formalism allows the capture of real-world data and the representation of complex wideband haptic
feedback. This type of haptics encoding has the disadvantage of being difficult to modify once encoded
due to the inability to access the primitives used to create the signal.
— Descriptive: This representation is used to encode haptic signals as a combination of functions to
be synthesized. Examples of such vectorized formats include AHAP and IVS. These formats have the
advantage of being created with a composition of primitives. They are easily modifiable at runtime
by an application and by dedicated editing tools. Currently, these solutions support only vibrotactile
perception, but can easily be extended for other forms of haptics such as kinaesthetic, temperature and
textures. They also tend to be memory inefficient with increasing signal complexity and cannot encode
non-periodic phenomena
This document describes the coded representation allowing to encode both descriptive and quantized data
in a human readable JSON format (.hjif) used as an exchange format. This format can be compressed and
packetized into a binary file format for distribution and streaming purposes (.hmpg).

© ISO/IEC 2025 – All rights reserved
vi
International Standard ISO/IEC 23090-31:2025(en)
Information technology — Coded representation of
immersive media —
Part 31:
Haptics coding
1 Scope
This document specifies technology that supports the efficient transmission and rendering of haptic signals
for the playback of immersive experiences in a wide variety of scenarios. The document describes in detail
a robust coded representation of haptic media covering the two most popular haptic perceptions leveraged
by devices today: vibrotactile and kinaesthetic. Support for other haptic modalities has also been integrated.
The coded representation allows to encode both descriptive and quantized data in a human readable JSON
format used for exchange purposes, and a compressed bitstream version, optimised for memory usage
and distribution purposes. This approach also allows to meet the expectations for compatibility with both
descriptive and quantized formats, as required by the market, as well as interoperability between devices
for 3D immersive experiences, mobile applications and other distribution purposes.
Information provided in this document related to the decoder is normative, while information related to the
encoder and renderer is informative.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules
ISO 8601-2, Date and time — Representations for information interchange — Part 2: Extensions
ISO/IEC 21778:2017, Information technology — The JSON data interchange syntax
IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax, available at: https:// www .rfc -editor .org/
info/ rfc3986
IETF RFC 8259, The JavaScript Object Notation (JSON) Data Interchange Format, available at: https:// www .rfc
-editor .org/ info/ rfc8259
IETF RFC 4648, The Base16, Base32, and Base64 Data Encodings, available at: https:// www .rfc -editor .org/
info/ rfc4648
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp

© ISO/IEC 2025 – All rights reserved
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
actuator
component of a device for rendering haptic sensations
3.1.2
avatar
body (or part of body) representation
3.1.3
band
component in a channel for containing effects for a specific range of frequencies
3.1.4
channel
component in a perception containing one or more bands rendered on a device at a specific body location
3.1.5
device
physical system having one or more actuators configured to render a haptic sensation corresponding with a
given signal
3.1.6
effect
component of a band for defining a signal, consisting of a haptic waveform or one or more haptic keyframes
3.1.7
experience
top level haptic component containing perceptions and metadata
3.1.8
haptics
tactile sensations
3.1.9
keyframe
component of an effect mapping a position in time or space to an effect parameter such as amplitude or
frequency
3.1.10
metadata
global information about an experience, perception, channel or band
3.1.11
MIHS format
self-contained stream for transporting MPEG-I haptic data
3.1.12
MIHS initialization unit
MIHS unit containing metadata necessary to reset and initialize a haptic decoder
3.1.13
MIHS packet
MIHS data packet which includes metadata or binary effect data
3.1.14
MIHS unit
MIHS data unit covering a duration of time

© ISO/IEC 2025 – All rights reserved
3.1.15
modality
type of haptics, such as vibration, force, pressure, position, velocity or temperature
3.1.16
perception
haptic perception containing one or more channels of a specific modality
3.1.17
signal
representation of the haptics associated with a specific modality to be rendered on a device
3.1.18
transient
short momentary effect defined by an amplitude and, directly or indirectly, a frequency
3.1.19
vector
direction in space which can be used for haptic signals spatialization
3.2 Abbreviated terms
AC Arithmetic coding/coder
AHAP Apple Haptic and Audio Pattern - JSON-like file format that specifies a haptic pattern
ATSC Advanced Television Systems Committee
CDF9/7 Cohen–Daubechies–Feauveau 9/7
CRC Cyclic redundancy check
DASH Dynamic Adaptive Streaming over HTTP (specified in ISO/IEC 23009)
FFT Fast Fourier Transform
HJIF Haptics JSON Interchange Format
ID Identifier
ISOBMFF ISO Base media file format (specified in ISO/IEC 14496-12)
IVS XML-based file format for representing haptic effects
JSON JavaScript Object Notation
LOD Level of Detail
MIHS MPEG-I Haptic Stream
MPEG Moving Picture Experts Group
MPEG-I MPEG Immersive media (specified in this and other parts of ISO/IEC 23090)
OHM Object Haptic Metadata - Text file format for haptics metadata
PCM Pulse-code modulation
SPIHT Set Partitioning In Hierarchical Trees

© ISO/IEC 2025 – All rights reserved
3.3 Mnemonics
The following data types are used for data specifications:
bslbf Bit string with left bit first, where “left” is the order in which bit strings are written. Bit strings
are written as a string of 1s and 0s within single quote marks, for example ‘10000001’.
vlcs8 Variable length character string. Contains string data stored as a character array encoded in UTF-8.
uimsbf Unsigned integer with most significant bit first.
imsbf Integer with most significant bit first.
vlclbf Variable length code with left bit first, where “left” refers to the order in which the variable
length codes are written.
duimsbf Decimal stored as unsigned integer with most significant bit first in a given range. Default range
is [-1,1]
islif Integer stream with left integer first, where “left” is the order in which integer strings are writ-
ten. Only for buffering.
vlislif Variable length integer stream with left integer first, where “left” refers to the order in which
the integers are written.
4 Overview and architecture
4.1 Overview
This document describes a coded representation of haptics based on a data model that enables the encoding
of both descriptive and quantized haptic data. Two complementary formats based on this shared data model
(Clause 5) are detailed in the specifications: an interchange format (.hjif) detailed in Clause 6, and a packetized
compressed binary format for streaming that can also be stored in a binary file (.hmpg) detailed in Clause 7.
In addition, a normative decoder and an informative encoder and synthesizer are described in detail.
The .hjif format is a human-readable format based on JSON and is not optimized for memory usage. It can
easily be parsed and manually edited, which makes it an ideal interchange format, especially when designing
or creating content. For distribution purposes, the .hjif data can be compressed and packetized into a more
memory efficient binary .hmpg bitstream. This compression is lossy, with different parameters impacting
the encoding depth of amplitudes and frequencies composing the bitstream. The compressed and packetized
data can be directly distributed as a MPEG-I haptic stream (MIHS).
4.2 Codec architecture
The generic codec architecture can process both waveform PCM signals (WAV) and descriptive haptic files
such as AHAP, IVS or HJIF, the proposed MPEG format. Metadata information is provided to the codec through
OHM input files (described in Annex B). An overview of the codec architecture is depicted in Figure 1, and a
more detailed description of the input files and encoder architecture is provided in Clause 8.

© ISO/IEC 2025 – All rights reserved
Figure 1 — Overview of the codec architecture
The encoder processes the two types of input files differently. For descriptive content, the input is analysed
semantically to transcode (if necessary) the data into the proposed coded representation. For PCM content,
the signal analysis process is split into two sub-processes. After performing a frequency band decomposition
on the signal, the different bands (one or more) can be encoded as a set of keyframes. In Figure 1, an
efficient example is given where the low frequencies are encoded using a keyframe extraction process. The
low frequency band(s) is(are) then reconstructed, and the error between this signal and the original low
frequency signal is computed. This residual signal is then added to the original high frequency band(s),
before encoding using wavelet transforms. This multi-bands hybrid encoding scheme is detailed in Clause 8.
The encoder can output two types of formats: an interchange file format (.hjif) encoded in JSON, and a binary
encoded streaming format (MIHS). that can also be stored as a binary file (.hmpg). The two formats have
complementary purposes, and a lossy one-to-one conversion can be operated between them. The encoder is
informative and is detailed in subclause 8.2.
The decoder takes as input a binary .hmpg file (the MIHS bitstream) or a .hjif file and either outputs a .hjif file
or directly synthesizes the haptic data. Haptic data contained in a .hjif file can be rendered directly on haptic
devices or using an intermediate synthesizer generating PCM data. The decoder is normative and is detailed
in subclause 8.3.
The synthesizer allows to render haptic data from a .hjif input file or MIHS stream into a PCM output file. The
synthesizer is informative and is detailed in subclause 8.3.4.
5 Data model
5.1 Data structure overview
This Clause focuses on the data model of the coded representation of haptics. It specifies the information
required by a synthesizer to render the haptic data. The following subclauses provide detailed definitions for
every property of each element of the data model depicted in Figure 2. The data structure introduced in this
Clause is shared by the interchange format and the streaming format defined respectively in Clauses 6 and 7.
The data structure of the two formats follows the hierarchical organization illustrated in Figure 2.

© ISO/IEC 2025 – All rights reserved
Figure 2 — General data model
The highest level of the structure describes the entire haptic experience defined in the file or stream. It
contains some high-level metadata information. It also provides a list of avatars (i.e., body representation)
referenced later in the file to specify the desired location of haptic stimuli on the body. Finally, the haptics
are described through a list of perceptions. These perceptions correspond to haptic signals associated with
specific perception modalities (e.g., vibration, force, position, velocity, temperature).
In addition to specific metadata, a perception contains a list of channels. The data in each channel are
decomposed into one or more frequency bands. Each band defines part of the signal in a frequency range. A
band is described by a list of haptic effects, each containing a list of keyframes. The haptic signal in a channel
can then be reconstructed by combining the data in the different bands as illustrated in Figure 3. For
instance, by adding the high and low frequency bands in this figure, the original signal can be reconstructed.
The perception and channel information describe the content (Description part of Figure 2), while the bands,
effects and keyframes contain the data of the encoded signals (Encoding part of Figure 2).

© ISO/IEC 2025 – All rights reserved
Key
1 keyframes
2 effects
A band 1 (curve band)
B band 2 (vectorial wave band)
C channel 1
Figure 3 — Haptic channel (bottom) and its decomposition in two frequency bands (top)
The format proposes four types of bands: transient bands, curve bands, vectorial wave bands and wavelet
wave bands. Each band is composed of a series of effects of the same type as the band, each defined by a list
of keyframes. The data contained in the effects and keyframes are interpreted differently for different types
of bands.
5.2 Haptic experience
The haptic experience defines the root of the hierarchical data model. It provides information on the date of
the file, the version of the format and the encoding profile and level. It also describes the haptic experience,
lists the different avatars (i.e., body representations) used throughout the experience, and defines all the
haptic perceptions. Table 1 details the properties of a haptic experience.
Table 1 — Haptic experience properties
Property Description
version Year of the edition and amendment of ISO/IEC 23090-31 that this file conforms to, in the following
format: XXXX or XXXX-Y, where XXXX is the year of publication and Y is the amendment number, if
any.
profile Name of the profile used to generate the encoded stream as defined in the normative Annex D.
level Number of the level used to generate the encoded stream as defined in the normative Annex D.
date Creation date of this haptic experience.
description A user description of this haptic experience.

© ISO/IEC 2025 – All rights reserved
TTaabbllee 11 ((ccoonnttiinnueuedd))
Property Description
timescale Number of ticks per second.
avatars List of avatars defining body representations used in the haptic experience. See subclause 5.3.
perceptions List of perceptions describing a haptic signal. See subclause 5.4.
5.3 Haptic avatar
Haptic avatars are used as body representations. Avatars can reference a custom 3D mesh from a companion
file. Each perception may be associated with an avatar, which allows spatialization of effects at the channel
level. The same avatar can be used by multiple perceptions.
A 3D mesh can provide resolution and accuracy with variable vertex density depending on the application.
For instance, the density can be representative of the spatial acuity of a specific perception modality
(Figure 4). The format of custom 3D meshes is out of the scope of this document.
Figure 4 — Example of haptic avatar body representations
Table 2 defines the list of properties of a haptic avatar:

© ISO/IEC 2025 – All rights reserved
Table 2 — Haptic avatar properties
Property Description
id Unique ID of the avatar in this experience.
lod If the avatar uses a mesh with several levels of detail (LODs), this indicates which LOD should be used
for the avatar.
type Type of haptic perception represented by the avatar. This is related to the spatial acuity of the corre-
sponding haptic modality. The avatar type may be:
— Vibration: the avatar is for vibrotactile signals.
— Pressure: the avatar is for pressure signals.
— Temperature: the avatar is for temperature signals.
— Custom: the avatar is a custom avatar. The mesh is provided as a companion file using the mesh URI.
The definition of custom mesh is out of the scope of this document.
mesh URI to access the associated 3D mesh file. The URI conforms to the syntax defined in RFC 3986.
5.4 Haptic perception
A haptic perception is a haptic signal associated with a specific perception modality. The format supports
different types of modalities, encoded in function of time (pressure, acceleration, velocity, position,
temperature, vibrotactile, water, wind, force, electrotactile) or space (vibrotactile texture, stiffness, friction).
The list of supported modalities is provided in Table 4 with the corresponding units and type (aka temporal
or spatial).
There is no accepted psychophysical representation set of tactile perception in function of a definite
representation space and stimulus. Touch shows remarkable complexity in the relations between physical
stimuli and the semantic assigned by
...