Inside a Virtual Acoustic Object
One semantic release. Multiple ways to carry and access its resources.
VAO 0.5.0 separates the semantic release from its physical carriers. The manifest describes resources and their relationships. A carrier packages exact realizations of those resources for transport. Changing the delivery arrangement does not, by itself, create a different semantic release.
Three carrier roles
| Carrier | Purpose |
|---|---|
| Bootstrap | A small entry point for discovery and evidence, with references to further resources. |
| Preservation closure | Contains every realization required by the complete release. |
| Custom | A locally materialized selection for a particular task or byte budget. |
Cuntz · Released record#
Why does the Cuntz release offer two VAO downloads?
A manifest describes the research object and its resource relationships. A carrier is a package that delivers some or all of those exact resources.
Work through the example 3 STEPS
The published Cuntz record offers a bootstrap carrier and a preservation carrier. The release states that both carry the same manifest; the preservation carrier includes every declared realization.
Begin with the inventory
The bootstrap supplies the semantic inventory and core evidence. It lets a reader discover what exists without first downloading all the media.
Request the required material
A geometry inspection needs the selected model and its dependencies. A playable experience may need audio, control mappings and other groups. Reading metadata does not make those resources locally available.
Choose preservation deliberately
The complete preservation carrier supports the full declared realization inventory. Cite the exact release and record which carrier or selected closure you actually acquired.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
A downloaded bootstrap does not prove that every external resource has been fetched or verified.
The useful distinction. One research release can have several delivery packages without becoming several historical interpretations.
A small, explicit container
VAO 0.5.0 · root structure
instrument.vao
├── mimetype
├── vao-manifest.json
├── META-INF/
│ └── vao-carrier.json
└── payload/
└── …The manifest fixes semantic identity. The carrier descriptor maps embedded payload members to that manifest. Byte sizes and SHA-256 digests let a client check whether a retrieved realization is the one the release actually identifies.
From a resource to its exact bytes
| Concept | Illustrative example |
|---|---|
| Logical asset | A recording of one documented take. |
| Realization | One particular encoding of that recording, identified by byte size and SHA-256. |
| Distribution | A location from which those exact bytes can be acquired. |
| Asset group | A declared set of resources and dependencies needed for a particular capability. |
A filename is a convenient label, not an identity guarantee. Re-encoding audio, editing a mesh or replacing an image changes the exact realization. Even when two files serve the same intellectual role, a client must not substitute one for the other without an explicit release description. A changed URL can still deliver the same realization; an unchanged URL can deliver different bytes.
Cuntz · Released record#
How can two model files represent one asset?
A logical asset names a role in the research object. A realization identifies one exact encoding of that asset. A distribution says where a realization can be obtained.
Work through the example 3 STEPS
The Cuntz manifest groups the 4010243_segmented_03b2 FBX source and GLB runtime model under one logical model asset. Their byte sizes, formats and digests differ.
Identify the shared asset
The asset groups representations serving the named model role. It supplies the connection that a filename alone cannot guarantee.
Inspect each realization
The FBX source is 61,745,100 bytes; the released GLB is 115,416,448 bytes. The GLB is marked derived, with a model-conversion activity. Each has an independent SHA-256.
Identify the notebook derivative separately
The smaller model served by this notebook is another derived file. Its caption and file identity distinguish it from both published realizations, and its provenance leads back to the released GLB.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
The smaller web derivative has not been retroactively inserted into the published VAO manifest.
The useful distinction. “Same asset” expresses a relationship; “same bytes” is a separate, testable claim.
What happens during selective delivery
- Read the bootstrap manifest and establish the fixed semantic release being requested.
- Choose a declared group, including its dependencies, that supports the intended use.
- Resolve the pinned preservation carrier and exact member mapping.
- Retrieve the member, then check its decoded byte length and SHA-256 against the manifest.
- Record the selection and materialized carrier so that a later user can understand what was acquired.
A small carrier is not automatically a complete preservation copy. Group completeness is a statement about included realizations and their recursively required groups. A browser preview might be sufficient for inspecting an image, while a later acoustic analysis needs another group. The release contract makes that difference explicit instead of letting a partial download masquerade as the whole object.
Say how each representation came into being
VAO 0.5.0 distinguishes statuses including captured, authored, converted, derived, simulated, inferred, reconstructed, redacted, hybrid and undetermined. These labels locate a representation within its history. A captured signal and a simulated signal may both be playable, but their scientific roles differ. A converted encoding preserves a relationship to an input; a reconstructed surface embodies additional assumptions. Retain the derivation evidence needed to interpret the chosen status.
Use exact realization identity when citing or comparing output. “The organ model” is too broad if a release contains a measured point cloud, a reconstructed mesh and a reduced mobile geometry. Name the relevant realization and retain its byte identity, then explain the relation it has to the other forms of the asset.
Sources & further reading
- VAO Standard 0.5.0
The versioned specification and reference tools.
- VAO Standard 0.5.0
Normative standard, profile index, Dynamic Delivery Profile and conformance specification in the versioned release.
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