# How does spatial audio for XR/immersive delivery (ASAF/APAC, IAMF, MPEG-H, OpenXR) differ in role and scope from the cinema/broadcast Audio Definition Model (ITU-R BS.2076-3)?

- id: art_01M5NNJHQAFDFEARF6FFCC8JD2
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=metadata_checked, execution=not_run, review=unreviewed
- categories: T13, T14, T19 · tags: none
- updated: 2026-10-24T00:39:35.396Z
- url: https://veyrul.com/articles/art_01M5NNJHQAFDFEARF6FFCC8JD2

Partially verified: the curator re-read S14, S18, S2; S13, S15 were not re-read by the curator and rest on the producer's pinned reading. ADM (ITU-R BS.2076-3, 2025) describes audio rather than carrying it: channels are typed DirectSpeakers, Matrix, Objects, HOA or Binaural, with head-locked and headphone-virtualise parameters, and the audio travels in BW64 with rendering left to a separate renderer. Apple's ASAF, by contrast, packages metadata with linear PCM in Broadcast Wave and depends on Apple's built-in renderer, which adapts to object and listener position and orientation; it is streamed as APAC. The Apple talk does not mention ADM, and no inspected source documents converting an ADM master to ASAF. IAMF combines audio elements and mix presentations for device-specific rendering.

Partially verified: the curator re-read S14, S18, S2; S13, S15 were not re-read by the curator and rest on the producer's pinned reading.

ADM (ITU-R BS.2076-3, 2025) describes audio rather than carrying it: channels are typed DirectSpeakers, Matrix, Objects, HOA or Binaural, with head-locked and headphone-virtualise parameters, and the audio travels in BW64 with rendering left to a separate renderer. Apple's ASAF, by contrast, packages metadata with linear PCM in Broadcast Wave and depends on Apple's built-in renderer, which adapts to object and listener position and orientation; it is streamed as APAC. The Apple talk does not mention ADM, and no inspected source documents converting an ADM master to ASAF. IAMF combines audio elements and mix presentations for device-specific rendering.

Curator qualifications: Partially verified: the curator re-read S14, S18, S2; S13, S15 were not re-read by the curator and rest on the producer's pinned reading. Curator GET 2026-10-23 of the sources not re-read (mechanical source evidence, not semantic verification): S13: HTTP 200, bytes equal to the producer pin; S15: HTTP 200, bytes differ from the producer pin. Recommendation, talk transcript and spec source read 2026-10-22; no audio rendered or converted. ATSC A/342 (MPEG-H) and OpenXR BD statements not reinspected. Whether ASAF metadata is ADM-derived is unknown.

Limitations: Recommendation, talk transcript and spec source read 2026-10-22; no audio rendered or converted.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://www.atsc.org/wp-content/uploads/2025/11/A342-3-2025-10-MPEG-H-System.pdf",
      "note": "[producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300"
    },
    {
      "url": "https://github.com/AOMediaCodec/iamf/blob/55683fae00e541cd4f0849918f19af0e04bc629c/index.bs",
      "note": "[producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300"
    },
    {
      "url": "https://registry.khronos.org/OpenXR/specs/1.1/html/xrspec.html",
      "note": "[producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300"
    },
    {
      "url": "https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.2076-3-202502-I!!PDF-E.pdf",
      "note": "[producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300"
    },
    {
      "url": "https://developer.apple.com/videos/play/wwdc2025/403",
      "note": "cited at https://developer.apple.com/videos/play/wwdc2025/403/; [producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300"
    },
    {
      "url": "https://developer.apple.com/videos/play/wwdc2025/403/",
      "note": "observed URL (dated/alias form of the cited catalogue source; canonical identity retained)"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] ADM (ITU-R BS.2076-3, 2025) describes audio rather than carrying it: channels are typed DirectSpeakers, Matrix, Objects, HOA or Binaural, with head-locked and headphone-virtualise parameters, and the audio travels in BW64 with rendering left to a separate renderer. Apple's ASAF, by contrast, packages metadata with linear PCM in Broadcast Wave and depends on Apple's built-in renderer, which adapts to object and listener position and orientation; it is streamed as APAC. The Apple talk does not mention ADM, and no inspected source documents converting an ADM master to ASAF. IAMF combines audio elements and mix presentations for device-specific rendering. · locator: [producer working copy; not public] sha256 337e78d026331dd8 (equal to pin S18); pdftotext lines 371, 461, 3404, 3853; Apple WWDC25 session 403 transcript, 11:21 Apple Spatial Audio Format and 12:39 APAC (live 2026-10-22); AOMediaCodec/iamf index.bs @55683fae lines 291-300 · source: https://www.atsc.org/wp-content/uploads/2025/11/A342-3-2025-10-MPEG-H-System.pdf

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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