Inside a Virtual Acoustic Object

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#

A small, explicit container#

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#

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.

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.