{ "title": "Inside a Virtual Acoustic Object — Virtual Acoustic Objects", "text": "MODAVIS (2026). Inside a Virtual Acoustic Object — Virtual Acoustic Objects. Research notebooks, September 2026 · research guides edition. https://modavis.org/editions/2026-09-r4/vao/structure/", "bibtex": "@misc{modavis_vao_structure_2026_09_r4,\n author = {{MODAVIS}},\n title = {Inside a Virtual Acoustic Object — Virtual Acoustic Objects},\n year = {2026},\n month = {09},\n version = {2026-09-r4},\n url = {https://modavis.org/editions/2026-09-r4/vao/structure/},\n note = {Content SHA-256: 2ad619db64d2ee2a2ca9f8137285c0ff095d40ae37cb1b322d94cacd0cc2c559}\n}", "url": "https://modavis.org/editions/2026-09-r4/vao/structure/", "sha256": "2ad619db64d2ee2a2ca9f8137285c0ff095d40ae37cb1b322d94cacd0cc2c559", "edition": "2026-09-r4", "date": "2026-09-26", "canonicalPayload": "{\"book\":{\"number\":\"01\",\"slug\":\"vao\",\"title\":\"Virtual Acoustic Objects\"},\"chapter\":{\"blocks\":[{\"text\":\"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.\",\"type\":\"p\"},{\"id\":\"carrier-roles\",\"text\":\"Three carrier roles\",\"type\":\"heading\"},{\"headers\":[\"Carrier\",\"Purpose\"],\"rows\":[[\"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.\"]],\"type\":\"table\"},{\"id\":\"container\",\"text\":\"A small, explicit container\",\"type\":\"heading\"},{\"label\":\"VAO 0.5.0 · root structure\",\"text\":\"instrument.vao\\n├── mimetype\\n├── vao-manifest.json\\n├── META-INF/\\n│ └── vao-carrier.json\\n└── payload/\\n └── …\",\"type\":\"code\"},{\"text\":\"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.\",\"type\":\"p\"},{\"text\":\"Where the repository supports byte ranges, a client can retrieve an exact stored ZIP member without first downloading the complete preservation carrier. This depends on the delivery service as well as the package.\",\"title\":\"Selective access\",\"type\":\"note\"},{\"id\":\"resource-identity\",\"text\":\"From a resource to its exact bytes\",\"type\":\"heading\"},{\"headers\":[\"Concept\",\"Illustrative example\"],\"rows\":[[\"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.\"]],\"type\":\"table\"},{\"text\":\"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.\",\"type\":\"p\"},{\"id\":\"delivery-sequence\",\"text\":\"What happens during selective delivery\",\"type\":\"heading\"},{\"items\":[\"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.\"],\"type\":\"list\"},{\"text\":\"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.\",\"type\":\"p\"},{\"text\":\"VAO 0.5.0 names the exchange contract. A reference instrument’s 0.5.0-rc.2 package label names that publisher’s object release. Similar-looking version strings do not establish an equivalence between the two.\",\"title\":\"Release version and format version\",\"type\":\"note\"},{\"id\":\"realization-status\",\"text\":\"Say how each representation came into being\",\"type\":\"heading\"},{\"text\":\"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.\",\"type\":\"p\"},{\"text\":\"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.\",\"type\":\"p\"},{\"items\":[{\"detail\":\"A worked guide to release, realization and distribution identity.\",\"href\":\"/notebooks/vao/delivery/\",\"label\":\"Follow an asset across carriers\"},{\"detail\":\"The relationships that make media interpretable.\",\"href\":\"/notebooks/vao/acoustics/\",\"label\":\"Time, space and acoustic response\"}],\"type\":\"links\"}],\"intro\":\"One semantic release. Multiple ways to carry and access its resources.\",\"slug\":\"structure\",\"sources\":[{\"detail\":\"The versioned specification and reference tools.\",\"href\":\"https://doi.org/10.5281/zenodo.22214248\",\"label\":\"VAO Standard 0.5.0\"},{\"detail\":\"Normative standard, profile index, Dynamic Delivery Profile and conformance specification in the versioned release.\",\"href\":\"https://doi.org/10.5281/zenodo.22214248\",\"label\":\"VAO Standard 0.5.0\"}],\"title\":\"Inside a Virtual Acoustic Object\"},\"date\":\"2026-09-26\",\"edition\":\"2026-09-r4\",\"figures\":{}}", "payload": { "edition": "2026-09-r4", "date": "2026-09-26", "book": { "slug": "vao", "title": "Virtual Acoustic Objects", "number": "01" }, "chapter": { "slug": "structure", "title": "Inside a Virtual Acoustic Object", "intro": "One semantic release. Multiple ways to carry and access its resources.", "blocks": [ { "type": "p", "text": "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." }, { "type": "heading", "text": "Three carrier roles", "id": "carrier-roles" }, { "type": "table", "headers": [ "Carrier", "Purpose" ], "rows": [ [ "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." ] ] }, { "type": "heading", "text": "A small, explicit container", "id": "container" }, { "type": "code", "label": "VAO 0.5.0 · root structure", "text": "instrument.vao\n├── mimetype\n├── vao-manifest.json\n├── META-INF/\n│ └── vao-carrier.json\n└── payload/\n └── …" }, { "type": "p", "text": "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." }, { "type": "note", "title": "Selective access", "text": "Where the repository supports byte ranges, a client can retrieve an exact stored ZIP member without first downloading the complete preservation carrier. This depends on the delivery service as well as the package." }, { "type": "heading", "text": "From a resource to its exact bytes", "id": "resource-identity" }, { "type": "table", "headers": [ "Concept", "Illustrative example" ], "rows": [ [ "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." ] ] }, { "type": "p", "text": "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." }, { "type": "heading", "text": "What happens during selective delivery", "id": "delivery-sequence" }, { "type": "list", "items": [ "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." ] }, { "type": "p", "text": "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." }, { "type": "note", "title": "Release version and format version", "text": "VAO 0.5.0 names the exchange contract. A reference instrument’s 0.5.0-rc.2 package label names that publisher’s object release. Similar-looking version strings do not establish an equivalence between the two." }, { "type": "heading", "id": "realization-status", "text": "Say how each representation came into being" }, { "type": "p", "text": "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." }, { "type": "p", "text": "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." }, { "type": "links", "items": [ { "label": "Follow an asset across carriers", "href": "/notebooks/vao/delivery/", "detail": "A worked guide to release, realization and distribution identity." }, { "label": "Time, space and acoustic response", "href": "/notebooks/vao/acoustics/", "detail": "The relationships that make media interpretable." } ] } ], "sources": [ { "label": "VAO Standard 0.5.0", "href": "https://doi.org/10.5281/zenodo.22214248", "detail": "The versioned specification and reference tools." }, { "label": "VAO Standard 0.5.0", "href": "https://doi.org/10.5281/zenodo.22214248", "detail": "Normative standard, profile index, Dynamic Delivery Profile and conformance specification in the versioned release." } ] }, "figures": {} } }