4. Haptic Format Description

Cette page resume la section correspondante du RFC 9993 et conserve RTP payload, MIHS, SDP et les details IANA.

The haptic coding overview and MIHS stream description, including Figure 1, are preserved below.

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), and also other less common perceptions, such as the sense of
   temperature or texture, for example.  It also supports two approaches
   for encoding haptic signals: a "quantized" approach based on samples
   of measured 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) 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

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

   +--------+ +-------+ +-------------+ +-------------+ +-----------+
   |Initial*| |Spatial| |Temporal Unit| |Temporal Unit| |Silent Unit|
   | Unit   |-| Unit  |-|   (indep.)  |-| (dependent) |-| (indep.)  |
   +--------+ +-------+ +-------------+ +-------------+ +-----------+
    *Initialization

                      Figure 1: Example of MIHS Stream