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

1      Definition

A Data Type including the Audio Objects of a scene, their time and arrangement in the scene, and the Rights that may be exercised on the scene.

In the following Object and Scene are to be read as Audio Object and Audio Scene, respectively.

2      Functional Requirements

Basic Scene Descriptors include

  1. Scene Space-Time information.
  2. Objects.
  3. Object Space-Time information
  4. Enrichment Data.
  5. Rights that may be exercised on the Scene.

The Space-Time of the Objects may be superseded by the Space-Time of the Scene.

3      Syntax

https://schemas.mpai.community/OSD/V1.4/data/BasicAudioSceneDescriptors.json

4      Semantics

Label Description
Header Basic Audio Scene Descriptors Header
– Standard‑BasicAudioSceneDescriptors The characters “OSD‑BAS‑V”
– Version Major version – 1 or 2 characters
– Dot‑separator The character “.”
– Subversion Minor version – 1 or 2 characters
MInstanceID Identifier of M‑Instance.
SceneDescriptorsID Identifier of Scene Descriptors.
ObjectCount Number of Objects in Scene.
SceneDescriptorsSpaceTime Space and Time of Scene Descriptors.
SceneObjects[] Set of Objects.
– SceneObject An Object.
– SceneObjectSpaceTime Space Time of Object.
Scene Enrichment Additional scene descriptors from app-related analysis.
– Listener Point of View Listener’s Position and Orientation in the Basic Audio Scene.
– Object Audio Characteristics Per OSD-OAC specification.
– MotionFlags Flags indicating whether an audio source is static, moving, or intermittent.
– ProximityClass Classification of audio sources by perceptual distance (near, mid, far).
– AcousticProfile Characteristics of the audio source (timbre, frequency range, loudness, reverberation).
– RankedAudioObjects Ordered list of audio sources ranked by computed salience.
– SalientAudioObjects Subset of RankedAudioObjects exceeding directive‑defined salience thresholds.
– EnrichmentTime Timestamp when enrichment was performed.
– AIMID Identifier of the AIM that provided enrichment data.
Rights Rights that may be exercised on the Scene.
DescrMetadata Descriptive Metadata.

5     Conformance Testing

A Data instance Conforms with Basic Scene Descriptors (OSD-BAS) 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