| 1 Definition | 2 Functional Requirements | 3 Syntax | 4 Semantics |
1 Definition
User Command (CAE-UCM) is End User’s data used to edit and control an Audio Scene by specifying navigation, remixing, spatial positioning, substitution, motion, and acoustic environment modifications of Audio Objects.
2 Functional Requirements
User Command shall support the following Functional Requirements:
| Audio Scene Navigation | Changing the position and/or orientation of the end user by specifying a new Listener Point of View. |
| Audio Remixing | Level (LUFS measured as specified by ITU‑R BS.1770) specifying amplification or attenuation of Audio Objects. Adding or removing Audio Objects from the scene. |
| Audio Object Repositioning | Specifying updated spatial positions (Point of View / Spatial Attitude) of Audio Objects. |
| Audio Object Substitution | Replacing Audio Objects or modifying their Qualifiers (e.g., language). |
| Audio Object Motion | Assigning motion attributes to Audio Objects using Spatial Attitude and Acoustic Profile. |
| Acoustic Environment Modification | Changing the acoustic characteristics applied to Audio Objects through Acoustic Profiles. |
3 Syntax
https://schemas.mpai.community/CAE3/V1.0/data/UserCommand.json
4 Semantics
| Label | Description |
| Header | User Command Header, format: “CAE-UCM-Vx.y”. |
| MInstanceID | Identifier of the M-Instance. |
| UEnvironmentID | Identifier of the User Environment. |
| UserCommandID | Identifier of the User Command. |
| UserCommandTime | Timestamp indicating when the command is issued. |
| UserCommandData | Set of Audio Scene editing commands. |
| – ListenerPoV | Defines the Listener’s Point of View (audio scene navigation). |
| – LUFS | Audio remixing level parameter. |
| – AddedObjects | List of Audio Objects added to the scene. |
| – RemovedObjects | List of Audio Objects removed from the scene. |
| – MovedObjects | Audio Objects with updated spatial positions. |
| – ChangedObjects | Audio Objects with modified qualifiers (e.g., language). |
| – ModifiedObjects | Audio Objects with modified Acoustic Profiles or motion characteristics. |
| DataXMData | Data Exchange Metadata describing the User Command instance. |
| DescrMetadata | Descriptive metadata. |
5 Conformance Testing
A Data instance conforms with User Command (CAE‑UCM) if:
- Its JSON Object validates against the User Command JSON Schema.
- Any included JSON Objects validate against their respective JSON Schemas.
- All data elements:
- Have the specified Data Types.
- Conform with the qualifiers defined in their JSON Schemas.