wdiff rfc9993.original rfc9993.txt

avtcore

Internet Engineering Task Force (IETF) HS Yang
Internet-Draft
Request for Comments: 9993 X. de Foy
Updates: 9695 (if approved) InterDigital
Intended status:
Category: Standards Track 21 January 2026
Expires: 25 July May 2026
ISSN: 2070-1721

RTP Payload Format for Haptics
draft-ietf-avtcore-rtp-haptics-14

Abstract

This memo specifies an RTP payload format for the MPEG-I haptic data. A
haptic media stream is composed of MIHS MPEG-I Haptic Stream (MIHS) units
including a MIHS
(MPEG-I Haptic Stream) unit header and zero or more MIHS packets. The RTP
payload header format allows for packetization of a MIHS unit in an
RTP packet payload as well as fragmentation of a MIHS unit into
multiple RTP packets. The original subtype registration for haptics/
hmpg, registered with IANA in RFC9695,
'haptics/hmpg' (RFC 9695) did not include any required or optional
parameters. This memo updates RFC9695 RFC 9695 and the haptics/
hmpg 'haptics/hmpg'
registration to add optional parameters. It also provides SDP Session
Description Protocol (SDP) usage information for the haptics 'haptics' media
type.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

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(IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.

Information about the current status of this document, any errata,
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material or to cite them other than as "work in progress."

This Internet-Draft will expire on 25 July 2026.
https://www.rfc-editor.org/info/rfc9993.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Definition . . . . . . . . . . . . . . . . . . . . . . . . . 3 Definitions
4. Haptic Format Description . . . . . . . . . . . . . . . . . . 4
4.1. Overview of Haptic Coding . . . . . . . . . . . . . . . . 5
4.2. MIHS format . . . . . . . . . . . . . . . . . . . . . . . 5 Format
5. Payload Format For for Haptics . . . . . . . . . . . . . . . . . 6
5.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 6
5.2. Payload Header . . . . . . . . . . . . . . . . . . . . . 7
5.3. Payload Structures . . . . . . . . . . . . . . . . . . . 7
5.3.1. Single Unit Payload Structure . . . . . . . . . . . . 8
5.3.2. Fragmented Unit Payload Structure . . . . . . . . . . 9
5.3.3. Aggregation Packet Payload Structure . . . . . . . . 10
5.4. MIHS Units Transmission and Reception Considerations . . 12
6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 13
6.1. Optional Parameters Definition . . . . . . . . . . . . . 13
6.2. SDP Parameter Registration . . . . . . . . . . . . . . . 16
7. SDP Considerations . . . . . . . . . . . . . . . . . . . . . 16
7.1. SDP Offer/Answer Considerations . . . . . . . . . . . . . 17
7.2. Declarative SDP Considerations . . . . . . . . . . . . . 19
8. Congestion Control Considerations . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10.1. Media Type Registration Update . . . . . . . . . . . . . 21
10.2. New SDP Parameters Media Registration
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1.
11.1. Normative References . . . . . . . . . . . . . . . . . . 22
12.2.
11.2. Informative References . . . . . . . . . . . . . . . . . 23
Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24

1. Introduction

Haptics provides users with tactile effects in addition to audio and
video, allowing them to experience sensory immersion. Haptic data is
mainly transmitted to devices that act as actuators and provides actuators, providing them
with information to operate according to the values defined in haptic
effects. The IETF registered haptics 'haptics' as a primary media type type, akin
to
audio 'audio' and video 'video' [RFC9695].

The MPEG Haptics Coding standard [ISO.IEC.23090-31] defines the data
formats, metadata, and codec architecture to encode, decode,
synthesize
synthesize, and transmit haptic signals. Within this MPEG standard,
a haptic media stream is composed of MIHS units including a MIHS unit
header and zero or more MIHS packets. The MIHS unit is a unit of
packetization suitable for streaming, streaming and is similar in essence to the
NAL (Network
Network Abstraction Layer) Layer (NAL) unit defined in some video
specifications. This document specifies how haptic data (MIHS units)
can be transmitted using the RTP protocol. This document follows
recommendations in [RFC8088] and [RFC2736] for RTP payload format
writers. This document does not specify synchronization (lip sync)
mechanisms between haptics and audio/video components. In addition,
this document specifies the associated SDP parameters and SDP Offer/
Answer offer/
answer considerations for the haptics 'haptics' media type.

2. Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.

3. Definition Definitions

This document uses the definitions of the MPEG Haptics Coding
standard [ISO.IEC.23090-31]. Some of these terms are provided here
for convenience.

Actuator: component Component of a device for rendering haptic sensations.

Avatar: body Body (or part of body) representation.

Band: component Component in a channel for containing effects for a specific
range of frequencies.

Channel: component Component in a perception containing one or more bands
rendered on a device at a specific body location.

Device: physical Physical system having one or more actuators configured to
render a haptic sensation corresponding with a given signal.

Effect: component Component of a band for defining a signal, consisting of a
haptic waveform or one or more haptic keyframes.

Experience: top level Top-level haptic component containing perceptions and
metadata.

Haptics: tactile Tactile sensations.

Keyframe: component Component of an effect mapping a position in time or space
to an effect parameter such as amplitude or frequency.

Metadata: global Global information about an experience, perception,
channel, or band.

MIHS unit: unit Unit of packetization of the MPEG-I Haptic Stream format,
which is used as unit of payload in the format described in this
memo. See Section 4 for details.

Modality: type Type of haptics, such as vibration, force, pressure,
position, velocity, or temperature.

Perception: haptic Haptic perception containing channels of a specific
modality.

Signal: representation Representation of the haptics associated with a specific
modality to be rendered on a device.

Hmpg format: hmpg is a A binary compressed format for haptics data.
Information is stored in a binary form form, and data compression is
applied on data at the band level. The haptics/hmpg 'haptics/hmpg' media
subtype is registered in [RFC9695] and updated by this memo.

Independent unit: a A MIHS unit is independent if it can be decoded
independently from earlier units. Independent units contain
timing information and are also called "sync units" in
[ISO.IEC.23090-31].

Dependent unit: a A MIHS unit is dependent if it requires earlier
units for decoding. Dependent units do not contain timing
information and are also called "non-sync units" in
[ISO.IEC.23090-31].

Time-independent effect: a A haptic effect that occurs regardless of
time. The tactile feedback of a texture is a representative
example. Time-independent effects are encoded in spatial MIHS
units, as defined in Section 4.2.

Time-dependent effect: a A haptic effect that varies over time. For
example, tactile feedback for vibration and force are time-dependent
effects, time-
dependent effects and are encoded in temporal MIHS units, as
defined in Section 4.2.

4. Haptic Format Description

4.1. Overview of Haptic Coding

The MPEG Haptics Coding standard specifies methods for efficient
transmission and the rendering of haptic signals, to enable immersive
experiences. It supports multiple types of perceptions, including
the most common vibrotactile (sense of touch that perceives
vibrations) and kinesthetic perceptions (tactile resistance or
force), but and also other, other less common perceptions, including for
example such as the sense of
temperature or texture. texture, for example. It also supports two approaches
for encoding haptic signals: a "quantized" approach based on samples
of measured data, data and a "descriptive" approach where the signal is
synthesized using a combination of functions. Both quantized and
descriptive data can be encoded in a text-based exchange format based
on JSON (.hjif), (.hjif) or in a binary packetized format for distribution and
streaming (.hmpg). This last format is referred to as the MIHS
format and is a base for the RTP payload format described in this
document.

4.2. MIHS format Format

MIHS is a stream format used to transport haptic data. Haptic data data,
including haptic effects effects, is packetized according to the MIHS format, format
and delivered to actuators, which operate according to the provided
effects. The MIHS format has two levels of packetization, packetization: MIHS units
and MIHS packets.

MIHS units are composed of a MIHS unit header and zero or more MIHS
packets. Four types of MIHS units are defined. An initialization
MIHS unit contains MIHS packets carrying metadata necessary to reset
and initialize a haptic decoder, including a timestamp. A temporal
MIHS unit contains one or more MIHS packets defining time-dependent
effects and providing provides modalities such as pressure, velocity, and
acceleration. The duration of a temporal unit is a positive number.
A spatial MIHS unit contains one or more MIHS packets providing time-
independent effects, such as vibrotactile texture, stiffness, and
friction. The duration of a spatial unit is always zero. A silent
MIHS unit indicates that there is no effect during a time interval interval,
and its duration is a positive number.

A MIHS unit can be marked as independent or dependent. When a
decoder processes an independent unit, it resets the previous effects
and therefore provides a haptic experience independent from any
previous MIHS unit. A dependent unit is the continuation of previous
MIHS units and cannot be independently decoded and rendered without
having decoded a previous MIHS unit(s). Initialization and spatial
MIHS units are always independent units. Temporal and silent MIHS
units can be dependent or independent units.

Figure 1 illustrates a succession of MIHS units in a MIHS stream.

Figure 1: Example of MIHS stream Stream

5. Payload Format For for Haptics

5.1. RTP Header Usage

The RTP header is defined in [RFC3550] and represented in Figure 2.
Unless contextualized below, the meaning of the fields depicted in
Figure 2 is the same as in Section 5.1 of [RFC3550].

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V=2|P|X| CC |M| PT | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Timestamp |
+---------------------------------------------------------------+
| Synchronization Source (SSRC) Identifier |
+---------------------------------------------------------------+
| Contributing Source (CSRC) Identifiers |
| .... |
+---------------------------------------------------------------+

Figure 2: RTP header Header for Haptic. Haptic

Marker bit (M): 1 bit. The marker bit SHOULD be set to one in the
first non-silent RTP packet after a period of haptic silence.
This enables jitter buffer adaptation and haptics device washout
(i.e., reset to a neutral position) prior to the beginning of the
burst with minimal impact on the quality of experience for the end
user. The marker bit in all other packets MUST be set to zero.

Timestamp (TS): 32 bits. A timestamp representing the sampling time
of the first sample of the MIHS unit in the RTP payload. The
clock frequency MUST be set to the sample rate of the encoded
haptic data and is conveyed out-of-band out of band (e.g., as an SDP
parameter).

5.2. Payload Header

The RTP payload header follows the RTP header. Figure 3 describes
the RTP payload header for Haptic.

+-+-+-+-+-+-+-+-+
|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+
|D| UT | L |
+-+-----+-------+

Figure 3: RTP Payload Header for Haptic. Haptic

D (Dependency, 1 bit): this This field is used to indicate indicates whether the MIHS unit
included in the RTP payload is, when is dependent (when its value is one,
dependent or, when one)
or independent (when its value is zero, independent. zero).

UT (Unit Type, 3 bits): this This field indicates the type of the MIHS
unit included in the RTP payload. UT field values are listed in
Figure 4.
Table 1.

L (MIHS Layer, 4 bits): this This field is an integer value which that
indicates the priority order of the MIHS unit included in the RTP
payload, as determined by the haptic sender (e.g., by the haptic
codec), based on application-specific needs. For example, the
sender may use the MIHS layer to prioritize perceptions with the
largest impact on the end-user experience. Zero corresponds to
the highest priority. The semantic of individual MIHS layers are
not specified and are left for the application to assign. In
cases where the sender does not use the L field to indicate the
priority order of the MIHS unit, the L value is '0'.

5.3. Payload Structures

Three different types of RTP packet payload structures are specified.
A single unit packet contains a single MIHS unit in the payload. A
fragmentation unit contains a subset of a MIHS unit. An aggregation
packet contains multiple MIHS units in the payload. The unit type
(UT) field of the RTP payload header, as shown in Figure 4, Table 1, identifies
both the payload structure and, in the case of a single-
unit single-unit
structure, also identifies the type of MIHS unit present in the payload.

+===========+===================+==========================+
| Unit Type | Payload Structure | Packet Type Name
Type Structure
------------------------------------------------------- |
+===========+===================+==========================+
| 0 | N/A | Unassigned |
+-----------+-------------------+--------------------------+
| 1 | Single | Initialization MIHS Unit |
+-----------+-------------------+--------------------------+
| 2 | Single | Temporal MIHS Unit |
+-----------+-------------------+--------------------------+
| 3 | Single | Spatial MIHS Unit |
+-----------+-------------------+--------------------------+
| 4 | Single | Silent MIHS Unit |
+-----------+-------------------+--------------------------+
| 5 | Aggr | Single-Time Aggregation |
| | | Packet (STAP) |
+-----------+-------------------+--------------------------+
| 6 | Aggr | Multi-Time Aggregation |
| | | Packet (MTAP) |
+-----------+-------------------+--------------------------+
| 7 | Frag | Fragmentation Unit

Figure 4: |
+-----------+-------------------+--------------------------+

Table 1: Payload structure type Structure Type for haptic Haptic

The payload structures are represented in Figure 5. 4. The single unit
payload structure is specified in Section 5.3.1. The fragmented unit
payload structure is specified in Section 5.3.2. The aggregation
packet payload structure is specified in Section 5.3.3. The padding
in the figures of these section sections refers to the RTP padding defined in
[RFC3550].

(a) single unit (b)fragmentation unit (c) aggregation packet

Figure 5: 4: RTP Transmission modes Modes

5.3.1. Single Unit Payload Structure

In a single unit payload structure, as described in Figure 6, 5, the RTP
packet contains the RTP header, followed by the payload header and
one single MIHS unit. The payload header follows the structure
described in Section 5.2. The payload contains a MIHS unit as
defined in [ISO.IEC.23090-31].

Figure 6: 5: Single Unit Payload Structure

5.3.2. Fragmented Unit Payload Structure

In a fragmented unit payload structure, as described in Figure 7, 6, the
RTP packet contains the RTP header, followed by the payload header, a
Fragmented Unit (FU) header, and a MIHS unit fragment. The payload
header follows the structure described in Section 5.2. The value of
the UT field of the payload header is 7. The FU header follows the
structure described in Figure 8. 7. In the case of fragmentation, all
RTP payload header fields MUST remain unchanged across all fragments.

Figure 7: 6: Fragmentation Unit Payload Structure

FU headers are used to enable fragmenting a single MIHS unit into
multiple RTP packets. Fragments of the same MIHS unit MUST be sent
in consecutive order with ascending RTP sequence numbers (with no
other RTP packets within the same RTP stream being sent between the
first and last fragment). FUs MUST NOT be nested, i.e., an FU MUST
NOT contain a subset of another FU.

Figure 8 7 describes a an FU header, including the following fields:

+---+---+---+---+---+---+---+---+
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
+---+---+---+---+---+---+---+---+
|FUS|FUE| RSV | UT |
+---+---+-----------+-----------+

Figure 8: 7: Fragmentation unit header Unit Header

FUS (Fragmented Unit Start, 1 bit): this This field MUST be set to 1 for
the first fragment, fragment and 0 for the other fragments.

FUE (Fragmented Unit End, 1 bit): this This field MUST be set to 1 for
the last fragment, fragment and 0 for the other fragments.

The combination FUS=1 and FUE=1 MUST NOT occur; such packets are
invalid.

RSV (Reserved, 3 bits): these These bits MUST be set to 0 by the sender
and ignored by the receiver.

UT (Unit Type, 3 bits): this This field indicates the type of the MIHS
unit this fragment belongs to, using values defined in Figure 4. Table 1.

The use of MIHS unit fragmentation in RTP means that a media receiver
can receive some fragments, but not other fragments. The missing
fragments will typically not be retransmitted by RTP. This results
in partially received MIHS units, which can be either dropped or used
by the decoding application, based on implementation. In cases where
consecutive fragments with FUE and FUS are lost, the receiver may in
some cases be
able to detect that surrounding fragments belong to a different
partially received MIHS unit (e.g., if the UT field holds a different
value).

5.3.3. Aggregation Packet Payload Structure

In an aggregation packet, as described in Figure 9, 8, the RTP packet
contains an RTP header, followed by a payload header, and, for and (for each
aggregated MIHS Unit, unit) a MIHS unit size followed by the MIHS unit.
The payload header follows the structure described in Section 5.2.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Payload Header | MIHS Unit 1 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MIHS Unit 1 |
| |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MIHS Unit 2 Size | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| MIHS Unit 2 |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |...OPTIONAL RTP padding Padding |
+-------------------------------+-------------------------------+

Figure 9: 8: Single-Time Aggregation Packet

Figure 9 8 shows a Single-Time Aggregation Packet (STAP), which can be
used to transmit multiple MIHS units that correspond to the same
timestamp. For example, if two frequencies are used for the same
content, they can be transmitted at once in a STAP. Multiple spatial
units can also be sent together in a STAP, since this type of haptics
data is time independent. The MIHS unit length field (16 bits) holds
the length of the MIHS unit following it, in bytes. The value of the
UT field of the payload header is 5.

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RTP Payload Header | MIHS Unit 1 Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS Offset | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| MIHS Unit 1 |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MIHS Unit 2 Size | TS Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS offset Offset | |
|-+-+-+-+-+-+-+-+ |
| MIHS Unit 2 |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |...OPTIONAL RTP padding Padding |
+-------------------------------+-------------------------------+

Figure 10: Multiple-time aggregation packet 9: Multiple-Time Aggregation Packet

Figure 10 9 shows a multi-time aggregation packet. Multi-Time Aggregation Packet (MTAP). It is used to
transmit multiple MIHS units with different timestamps, in one RTP
packet. Multi-time aggregation can help reduce the number of
packets, packets
in environments where some delay is acceptable. The value of the UT
field of the Payload Header payload header is 6. The MIHS unit length field (16
bits) holds the length of the MIHS unit following it, in bytes. The
timestamp offset field (TS offset, 16 bits) is present in the MTAP case,
case and MUST be set to the value of (time of the MIHS unit - RTP
timestamp of the packet). The timestamp offset of the earliest
aggregation unit MUST always be zero. Therefore, the RTP timestamp
of the MTAP is identical to the earliest MIHS unit time.

5.4. MIHS Units Transmission and Reception Considerations

The following considerations apply for the streaming of MIHS units
over RTP: RTP.

The MIHS format enables variable duration units and uses
initialization MIHS units to declare the duration of subsequent non-
zero duration MIHS units, as well as the maximum variation of this
duration. A sender SHOULD set constant or low-variability (e.g.,
lower than the playout buffer) durations in initialization MIHS
units, for RTP streaming. This enables the receiver to determine
early (e.g., using a timer) when a unit has been lost and to make the
decoder more robust to RTP packet loss. If a sender sends MIHS units
with high duration variations, the receiver MAY need to wait for a
long period of time (e.g., the upper bound of the duration
variation), variation)
to determine if a MIHS unit was lost in transmission. Whether this
behavior is acceptable or not is application dependent, and the
application can configure the encoder to generate MIHS unit of
lengths with the appropriate variation.

The MIHS format uses silent MIHS units to signal haptic silence. A
sender MAY decide not to send silent units, to save network
resources. Since, from a receiver standpoint, a missed MIHS unit may
originate from a not-sent silent unit, unit or a lost packet, a sender MAY
send one, or a few, MIHS silent units at the beginning of a haptic
silence. If a media receiver receives a MIHS silent unit, the
receiver SHOULD assume that silence is intended until the reception
of a non-silent MIHS unit. This can reduce the number of false
detections of lost RTP packets by the decoder.

In some multimedia conference scenarios using an RTP video mixer
(e.g., when adding or selecting a new source), it is recommended to
use Full Intra Request (FIR) feedback messages [RFC5104] with Haptics
[RFC5104].
Haptics. The purpose of the FIR message is to cause an encoder to
send a decoder refresh point at the earliest opportunity. In the
context of haptics, an appropriate decoder refresh point is an
initialization MIHS unit. The initialization MIHS unit point enables
a decoder to be reset to a known state and be able to decode all MIHS units
following it.

6. Payload Format Parameters

This section describes payload format parameters. Section 6.1
specifies new optional parameters parameters, and Section 6.2 further registers
a new token in the media sub-registry subregistry of the Session "Session Description
Protocols
Protocol (SDP) Parameters registry. Parameters" registry group.

6.1. Optional Parameters Definition

It is optional to include the SDP parameters in this section. Some
parameters have a default value which that MUST be inferred if the
parameter is not present in the SDP, unless an out-of-band agreement
indicates a different value, as described in Section 7.1. The values
of the SDP parameters indicated in this section are based on the
current version of the MPEG Haptics Coding standard (ISO/IEC
23090-31:2025) and may be different in future versions of
[ISO.IEC.23090-31].

ver:

This parameter provides the year of the edition and amendment of ISO/
IEC 23090-31 that this file conforms to, as defined in
[ISO.IEC.23090-31]: MPEG_haptics object.version is a string which that may
hold values such as XXXX or XXXX-Y where XXXX is the year of
publication and Y is the amendment number, if any. For the initial
(and current) version of the MPEG Haptics Coding standard (ISO/IEC
23090-31:2025) ,
23090-31:2025), the value is "2025". When ver is not present, a
default value of "2025" SHOULD be inferred.

profile: This parameter indicates the profile used to generate the
encoded
stream stream, as defined in [ISO.IEC.23090-31]: MPEG_haptics
object.profile is a string which that may hold the values "simple-parametric" "simple-
parametric" or "main". When profile is not present, the default
value "main" SHOULD be inferred.

lvl: This parameter indicates the level used to generate the encoded
stream
stream, as defined in [ISO.IEC.23090-31]: MPEG_haptics
object.level is an integer which that may hold the values 1 or 2. When
lvl is not present, the default value 2 SHOULD be inferred.

maxlod: This parameter indicates the maximum level of details (LODs)
to use for the avatar(s). The avatar level of detail (LOD) LOD is defined in
[ISO.IEC.23090-31]: MPEG_haptics.avatar object.lod is an integer
which
that may hold the value 0 or a positive integer.

avtypes: This parameter indicates, using a comma-separated list, the
types of haptic perception represented by the avatar(s). The
avatar type is defined in [ISO.IEC.23090-31]: MPEG_haptics.avatar
object.type is a string which that may hold values among "Vibration",
"Pressure", "Temperature", or "Custom".

modalities: This parameter indicates, using a comma-separated list,
haptic perception modalities (e.g., pressure, acceleration,
velocity, position, temperature, etc.). The perception modality
is defined in [ISO.IEC.23090-31]: MPEG_haptics.perception
object.perception_modality is a string which that may hold values among
"Pressure", "Acceleration", "Velocity", "Position", "Temperature",
"Vibrotactile", "Water", "Wind", "Force", "Electrotactile",
"Vibrotactile Texture", "Stiffness", "Friction", "Humidity", "User-
defined
"User-defined Temporal", "User-defined Spatial", or "Other".

bodypartmask: This parameter is an integer which that indicates, using a
bitmask, the location of the devices or actuators on the body.
The body part mask is defined in [ISO.IEC.23090-31]:
MPEG_haptics.reference_device object.body_part_mask is a 32-bit
integer which that may hold a bit mask using bit positions defined in table
Table 7 of [ISO.IEC.23090-31].

maxfreq: This parameter is an integer which that indicates the maximum
frequency of haptic data for vibrotactile perceptions (Hz).
Maximum frequency is defined in [ISO.IEC.23090-31]:
MPEG_haptics.reference_device object.maximum_frequency.

minfreq: This parameter is an integer which that indicates the minimum
frequency of haptic data for vibrotactile perceptions (Hz).
Minimum frequency is defined in [ISO.IEC.23090-31]:
MPEG_haptics.reference_device object.minimum_frequency.

dvctypes: This parameter is an integer that indicates, using a
comma-separated list, the types of actuators. The device type is
defined in [ISO.IEC.23090-31]: MPEG_haptics.reference_device
object.type is a string which that may hold values among "LRA", "VCA",
"ERM", "Piezo" "Piezo", or "Unknown".

silencesupp: This parameter is an integer which that indicates whether
silence suppression should be used (1) (value 1) or not (0). (value 0).
When silencesupp is not present, the default value 0 SHOULD be
inferred.

6.2. SDP Parameter Registration

This memo registers a 'haptics' token in the media sub-registry subregistry of the Session
"Session Description Protocols Protocol (SDP) Parameters registry. Parameters" registry group. This
registration contains the required information elements outlined in
the SDP registration procedure defined in section Section 8.2 of [RFC8866].

(1)

Contact Information:

Name: name: Hyunsik Yang
Email:

Contact email address: hyunsik.yang@interdigital.com

(2)

Name being registered defined (as it will appear in SDP): haptics

(3) Long-form name in English: haptics

(4)

Type of name ('media', 'proto', 'fmt', 'bwtype', 'nettype', or
'addrtype'): media

(5) Purpose of the registered name: media

Description: The 'haptics' media type for the Session Description
Protocol is used to describe a media stream whose content can be
rendered as touch-related sensations. The media subtype further
describes the specific format of the haptics stream. The
'haptics' media type for SDP is used to establish haptics media
streams.

(6) Specification for the registered name: RFC XXXX

RFC Editor Note: Replace RFC XXXX with the published

Reference: RFC number. 9993

7. SDP Considerations

The mapping of above defined the above-defined payload format media type to the
corresponding fields in the Session Description Protocol (SDP) SDP is done according to [RFC8866].

The media name in the "m=" line of SDP MUST be haptics.

The encoding name in the "a=rtpmap" line of SDP MUST be hmpg hmpg.

The clock rate in the "a=rtpmap" line may be any sampling rate,
typically 8000.

The optional parameters (defined in Section 6.1), when present, MUST
be included in the "a=fmtp" line of SDP. This is expressed as a
media type string, in the form of a semicolon-separated list of
parameter=value pairs. Parameter values, including string values,
MUST be written without quotation marks ("") in SDP. Parameter
values which that are strings are not case sensitive and SHOULD be written
in lowercase.

An example of media representation corresponding to the hmpg RTP
payload in SDP is as follows:

m=haptics 43291 UDP/TLS/RTP/SAVPF 115
a=rtpmap:115 hmpg/8000
a=fmtp:115 profile=main;lvl=1;ver=2025

7.1. SDP Offer/Answer Considerations

When using the offer/answer procedure described in [RFC3264] to
negotiate the use of haptic, the following considerations apply:

When used for a unidirectional stream, the SDP parameters represent
the properties of the sender (on the sending side) and of the
receiver (on the receiving side). When used for a sendrecv stream,
the SDP parameters represent the properties of the receiver.

The receiver properties expressed using the SDP parameters 'ver',
'profile'
'profile', and 'lvl' correspond to implementation capabilities. The
ver, profile, and lvl parameters MUST be used symmetrically in SDP
offer and answer. That is, their values in the answer MUST match
those in the offer, either explicitly signaled or implicitly
inferred. In the same session, ver, profile, and lvl MUST NOT be
changed in subsequent offers or answers.

The properties expressed using SDP parameters other than 'ver',
'profile'
'profile', and 'lvl' are provided as recommendations for efficient
data transmission and are not binding, meaning that a sender is
encouraged but not required to conform to the parameters specified by
the receiver. These properties MAY be set to different values in
offers and answers. These properties MAY be updated in subsequent
offers or answers.

Any receiver compliant with [ISO.IEC.23090-31] MUST be capable of
decoding any stream with a compatible version, profile, and level. A
receiver supporting a more general profile will accept a stream
corresponding to a the same or a less general profile (e.g., "main" is
more general than "simple-parametric"). A receiver supporting a
given level will accept a stream corresponding to a the same or a lower
level. A receiver supporting a given version will accept a stream
corresponding to the same version and MAY accept other versions. A
receiver MAY ignore any part of a received stream, e.g., that it does
not have support for rendering.

The haptic signal can be sampled at different rates. The MPEG
Haptics Coding standard does not mandate a specific frequency. A
typical sample rate is 8000Hz.

The parameter 'ver' indicates the version of the haptic standard
specification. If it is not specified, the The parameter 'ver' indicates
the version of the haptic standard specification. If it is not
specified, the value "2025" indicating the MPEG Haptics Coding
standard ISO/IEC 23090-31:2025 [ISO.IEC.23090-31] SHOULD be inferred,
although the sender and receiver MAY use a specific value based on an
out-of-band agreement. The parameter 'profile' is used to restrict
the number of tools used (e.g., the simple-parametric profile fits
enable enables
simpler implementations than the main profile). If it is not
specified, the most general profile "main" SHOULD be inferred,
although the sender and receiver MAY use a specific value based on an
out-of-band agreement. The parameter 'lvl' is used to further
characterize implementations within a given profile, e.g., according
to the maximum supported number of channels, bands, and perceptions.
If it is not specified, the most general level "2" SHOULD be
inferred, although the sender and receiver MAY use a specific version
based on an out-of-band agreement.

Other parameters can be used to indicate bitstream properties as well
as receiver capabilities. The parameters 'maxlod', 'avtypes',
'bodypartmask', 'maxfreq', 'minfreq', 'dvctypes', and 'modalities'
can be sent by a sender to reflect the characteristics of bitstreams
and can be set by a receiver to reflect the nature and capabilities
of local actuator devices, devices or a preferred set of bitstream properties.
For example, different receivers MAY have different sets of local
actuators, in which case these parameters can be used to select a
stream adapted to the receiver. In some other cases, some receivers
MAY indicate a preference for a set of bitstream properties such as
perceptions, min/max frequency, or body-part-mask, which contribute
the most to the user experience for a given application, in which
case these parameters can be used to select a stream which
include that includes
and possibly prioritizes those properties. For example, if the
haptic stream server provides more information than the body mask
specified by the receiver, the additional information can be either
integrated into a single effect or ignored by the receiver.

The parameter 'silencesupp' can be used to indicate sender and
receiver capabilities or preferences. This parameter indicates
whether silence suppression should be used, as described in
Section 5.4. If it is not specified, the value "0", indicating no
silence suppression, SHOULD be inferred, although the sender and
receiver MAY use silence suppression based on an out-of-band
agreement.

7.2. Declarative SDP Considerations

When haptic content over RTP is offered with SDP in a declarative
style, the parameters capable of indicating both bitstream properties
as well as receiver capabilities are used to indicate only bitstream
properties. For example, in this case, the parameters maxlod,
bodypartmask, maxfreq, minfreq, dvctypes, 'maxlod',
'bodypartmask', 'maxfreq', 'minfreq', 'dvctypes', and modalities 'modalities'
declare the values used by the bitstream, not the capabilities for
receiving bitstreams. A receiver of the SDP is required to support
all parameters and values of the parameters provided; otherwise, the
receiver MUST reject or not participate in the session. It falls on
the creator of the session to use values that are expected to be
supported by the receiving application.

8. Congestion Control Considerations

The general congestion control considerations for transporting RTP
data apply to HMPG haptics over RTP as well [RFC3550].

It is possible to adapt network bandwidth usage by adjusting either
the encoder bit rate or by adjusting the stream content (e.g., level
of detail, the LOD, body
parts, actuator frequency range, target device types, and
modalities). The considerations in this section are applicable to
best-effort networks and controlled environments.

In case of congestion, a receiver or intermediate node MAY prioritize
independent packets over dependent ones, since the non-reception of
an independent MIHS unit can prevent the decoding of multiple
subsequent dependent MIHS units. In case of congestion, a receiver
or intermediate node MAY prioritize initialization MIHS units over
other units, since initialization MIHS units contain metadata used to
re-initialize
reinitialize the decoder, and MAY drop silent MIHS units before other
types of MIHS units, since a receiver MAY interpret a missing MIHS
unit as a silence. It is also possible, using the layer field of the
RTP payload header, to allocate MIHS units to different layers based
on their content, content to prioritize haptic data contributing that contributes the most
to the user experience. In case of congestion, intermediate nodes
and receivers SHOULD use the MIHS layer value to determine the
relative importance of haptic RTP packets.

Receivers should monitor timestamps and treat gaps as loss of the
corresponding MIHS units. MIHS units, as defined in
[ISO.IEC.23090-31], should be checked for structural integrity
according to their type. When CRC16 or CRC32 information is present
in MIHS units, receivers must validate data integrity, and units
failing CRC checks Cyclic Redundancy Checks (CRCs) should be treated as lost.
Receivers should further monitor indicators of service degradation
such as unexpected silent gaps, repeated decoder reinitializations,
or decoding failures. Receivers should report packet loss to the
sender using RTCP Receiver Reports [RFC3550] and, when available, may
report detailed loss and jitter metrics using mechanisms described in
[RFC4585].

9. Security Considerations

This

The RTP payload format is subject to security threats commonly
associated with RTP payload formats, as well as threats specific to
the interaction of haptic devices with the physical world, world and threats
associated with the use of compression by the codec. Security consideration
considerations for threats commonly associated with RTP payload
formats are outlined in [RFC3550], as well as in RTP profiles such as
RTP/AVP [RFC3551]), [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711],
or RTP/SAVPF and RTP/
SAVPF [RFC5124].

Haptic sensors and actuators operate within the physical environment.
This introduces the potential for information leakage through
sensors, sensors
or damage to actuators due to data tampering. Additionally, misusing
the functionalities of actuators (such as force, position,
temperature, vibration, electro-tactile, electrotactile, etc.) may pose a risk of harm
to the user, for example example, by setting keyframe parameters (e.g.,
amplitude, position, and frequency) or channel gain to a value that
surpasses a permissible range. While individual devices can
implement security measures to reduce or eliminate those risks on a
per-device basis, in some cases cases, harm can be inflicted by setting
values which that are permissible for the individual device. For example,
causing contact with the physical environment or triggering
unexpected force feedback can potentially harm the user. Each haptic
system should therefore implement system-dependent security measures,
which are more error prone. To limit the risk that attackers exploit
weaknesses in haptic systems, it is important that haptic
transmission should be protected against malicious traffic injection or
tampering.

However, as "Securing the RTP Framework: Why RTP Does Not Mandate a
Single Media Security Solution" [RFC7202] discusses, it is not an RTP
payload format's responsibility to discuss or mandate what solutions
are used to meet the basic security goals like confidentiality,
integrity, and source authenticity for RTP in general. The
responsibility for implementing security mechanisms lies with the
application developer. They can find guidance on available security
mechanisms and important considerations in "Options for Securing RTP
Sessions" [RFC7201], although [RFC7201] is now considered dated and
several mechanisms described therein have since evolved.

Applications SHOULD use appropriate and current strong security
mechanisms. For modern best practices, applications can consider the
following options:

* (D)TLS-based protection: For guidance on using TLS 1.3 and DTLS,
applications should refer to BCP 195, including [RFC9325], which
provides up-to-date recommendations.

* IPsec-based protection: Relevant and current protocol
specifications include [RFC4303] (ESP) ("IP Encapsulating Security
Payload (ESP)") and [RFC7296] (IKEv2). ("Internet Key Exchange Protocol
Version 2 (IKEv2)").

This document does not mandate a specific security mechanism.
Instead, applications are responsible for selecting mechanisms that
follow current best practices for confidentiality, integrity, and
source authentication, authentication and that reflect the evolving security
landscape beyond what is covered in [RFC7201].

The haptic codec used with this payload format uses a compression
algorithm (see sections Sections 8.2.8.5 and 8.3.3.2 in [ISO.IEC.23090-31]).
An attacker may inject pathological datagrams into the stream which that
are complex to decode and cause the receiver to be overloaded,
similarly to [RFC3551].

End-to-end security with authentication, integrity, or
confidentiality protection will prevent a Media-Aware Network Element
(MANE) from performing media-aware operations other than discarding
complete packets. In the case of confidentiality protection, it will
even be prevented from discarding packets in a media-aware way. To
be allowed to perform such operations, a MANE is required to be a
trusted entity that is included in the security context
establishment.

10. IANA Considerations

10.1. Media Type Registration Update

This memo updates the 'hmpg' haptic subtype defined in [RFC9695] for
use with the MPEG-I haptics streamable binary coding format described
in ISO/IEC 23090-31: Haptics coding [ISO.IEC.23090-31]. This memo
especially
defines optional parameters for this type in Section 6.1. The
original subtype registration for haptics/hmpg, 'haptics/hmpg', registered with
IANA in [RFC9695], did not include any required or optional
parameters. This document introduces optional parameters to enable
extended functionality while maintaining backward compatibility.

A mapping of the parameters into the Session Description Protocol
(SDP) SDP [RFC8866] is also provided for
applications that use SDP. Equivalent parameters could be defined
elsewhere for use with control protocols that do not use SDP. The
receiver MUST ignore any parameter unspecified in this memo.

This document requests an SDP parameters

IANA has updated the registration for the haptic
media type, as 'haptics', described in
Section 6.2. 6.2, in the "haptics" registry within the "Media Types"
registry group and listed document as an additional reference.

The following entries identify the media type being updated: updates to the 'media/haptics'
registration:

Type name: haptics

Subtype name: hmpg

The following entries are replaced by this memo:

Optional parameters: see section See Section 6.2 of RFC XXX (note to RFC editor:
replace with this RFC's number). 9993

Person & email address to contact for further information: Yeshwant
Muthusamy (yeshwant@yeshvik.com) and Hyunsik Yang
(hyunsik.yang@interdigital.com)

11. Acknowledgments

Thanks to Philippe Guillotel, Quentin Galvane, Jonathan Lennox,
Marius Kleidl and Stephan Wenger for

10.2. New SDP Parameters Media Registration

IANA has registered the comments and discussions
about this draft.

12. following in the "media" registry within the
"Session Description Protocol (SDP) Parameters" registration group.

+=======+==========+===========+
| Type | SDP Name | Reference |
+=======+==========+===========+
| media | haptics | RFC 9993 |
+-------+----------+-----------+

Table 2

11. References

12.1.

11.1. Normative References

[ISO.IEC.23090-31]
ISO/IEC, "Information technology - Coded representation of
immersive media", ISO/IEC media - Part 31: Haptics coding", ISO/
IEC 23090-31:2025, 2025,
<https://www.iso.org/standard/86122.html>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
<https://www.rfc-editor.org/info/rfc2119>.

[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/rfc/rfc3264>.
<https://www.rfc-editor.org/info/rfc3264>.

[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/rfc/rfc3550>. <https://www.rfc-editor.org/info/rfc3550>.

[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. <https://www.rfc-editor.org/info/rfc8174>.

[RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
Session Description Protocol", RFC 8866,
DOI 10.17487/RFC8866, January 2021,
<https://www.rfc-editor.org/rfc/rfc8866>.
<https://www.rfc-editor.org/info/rfc8866>.

[RFC9695] Muthusamy, Y. K. and C. Ullrich, "The 'haptics' Top-Level
Media Type", RFC 9695, DOI 10.17487/RFC9695, March 2025,
<https://www.rfc-editor.org/rfc/rfc9695>.

12.2.
<https://www.rfc-editor.org/info/rfc9695>.

11.2. Informative References

[RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP
Payload Format Specifications", BCP 36, RFC 2736,
DOI 10.17487/RFC2736, December 1999,
<https://www.rfc-editor.org/rfc/rfc2736>.
<https://www.rfc-editor.org/info/rfc2736>.

[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003,
<https://www.rfc-editor.org/rfc/rfc3551>.
<https://www.rfc-editor.org/info/rfc3551>.

[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004,
<https://www.rfc-editor.org/rfc/rfc3711>.
<https://www.rfc-editor.org/info/rfc3711>.

[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/rfc/rfc4303>.
<https://www.rfc-editor.org/info/rfc4303>.

[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006,
<https://www.rfc-editor.org/rfc/rfc4585>.
<https://www.rfc-editor.org/info/rfc4585>.

[RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
"Codec Control Messages in the RTP Audio-Visual Profile
with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
February 2008, <https://www.rfc-editor.org/rfc/rfc5104>. <https://www.rfc-editor.org/info/rfc5104>.

[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
2008, <https://www.rfc-editor.org/rfc/rfc5124>. <https://www.rfc-editor.org/info/rfc5124>.

[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
<https://www.rfc-editor.org/rfc/rfc7201>.
<https://www.rfc-editor.org/info/rfc7201>.

[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
2014, <https://www.rfc-editor.org/rfc/rfc7202>. <https://www.rfc-editor.org/info/rfc7202>.

[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/rfc/rfc7296>. <https://www.rfc-editor.org/info/rfc7296>.

[RFC8088] Westerlund, M., "How to Write an RTP Payload Format",
RFC 8088, DOI 10.17487/RFC8088, May 2017,
<https://www.rfc-editor.org/rfc/rfc8088>.
<https://www.rfc-editor.org/info/rfc8088>.

[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/rfc/rfc9325>. <https://www.rfc-editor.org/info/rfc9325>.

Acknowledgments

Thanks to Philippe Guillotel, Quentin Galvane, Jonathan Lennox,
Marius Kleidl, and Stephan Wenger for the comments and discussions
about this document.

Authors' Addresses

Hyunsik Yang
InterDigital
United States of America
Email: hyunsik.yang@interdigital.com

Xavier de Foy
InterDigital
Canada
Email: xavier.defoy@interdigital.com