1     Definition 2     Functional Requirements 3     Syntax
4     Semantics 5    Conformance Testing 6     Performance Assessment

1      Definition

Audio Proximity Class is a Data Type representing the perceived distance class of Audio Objects relative to the user within an OSD-defined Virtual Space. It provides a discrete proximity level (e.g., Near, Mid, Far), an associated confidence score, an optional distance estimate, and the time window over which the proximity was evaluated.

2      Functional Requirements

  • Per-Object Classification – Each Audio Object shall be assigned a discrete proximity level
    (Near, Mid, Far).
  • Confidence – Each proximity classification shall include a confidence value in the range [0..1].
  • Optional Distance Estimate – When available, a distance estimate (in metres) may be reported for an Audio Object.
  • Instance Binding – The set of proximity classes shall be bound to an Audio Scene.
  • Extensibility – The specification shall allow future expansion of proximity levels, estimation methods,
    and auxiliary attributes without breaking compatibility.

3      Syntax

https://schemas.mpai.community/OSD/V1.5/types/AudioProximityClass.json

4      Semantics

Table 1 provides the semantics of the components of Audio Proximity Class.

Table 1 – Semantics of the Audio Proximity Class

Label Description
Header Spatial Cue Header – Standard “OSD-APC-Vx,y”.
MInstanceID ID of Virtual Space the audio scene refers to.
AudioProximityClassID Identifier of Audio Proximity Class entry.
AudioProximityClass[] List of proximity classifications, one per Audio Object.
– AudioObjectID Unique identifier of the Audio Object.
– ProximityLevel Discrete proximity class relative to the user: Near, Mid, or Far.
– ProximityConfidence Confidence score (0–1) associated with the proximity classification.
– DistanceEstimate Optional distance in metres from the user for the Audio Object.
– TemporalWindow Evaluation window represented using OSD/V1.5/data/Time.json.
DataExchangeMetadata Metadata optionally used for regulated exchange of Audio Proximity Class information.
Trace Provenance trace including Source and Time per AIF V3.0 rules.
DescrMetadata Descriptive Metadata (max 2048 characters).

5     Conformance Testing

A Data instance Conforms with V1.5 Spatial Cue (OSD-APC) if:

  1. Its JSON Object validates against its JSON Schema.
  2. Any included  JSON Object validates against its JSON Schema.
  3. All Data in the JSON Object:
    1. Have the specified Data Types.
    2. Conform with the Qualifiers signaled in their JSON Schemas.

6     Performance Assessment