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Media & communications — delivery specs and content credentials

For a broadcaster, publisher or agency, "done" means the asset meets a delivery spec and its provenance is acceptable. verel.media grades both deterministically and offline, on the same verdict bus, gate and signed receipts as every other organ.

Grader Grades Gates Command
MEDIA declared rules over supplied measurement facts (loudness, true peak, A/V sync, track durations, caption languages…) yes verel-ci media
PROVENANCE C2PA content credentials against a declared policy yes verel-ci provenance

Who measures what

Verel does not measure media. The senses do, and hand Verel a facts file:

  • Audel (ears): integrated loudness, true peak, loudness range, silence, clipping, speech.
  • AgentVision (eyes): frame, caption and on-screen state.
  • ffprobe or any tool: container, duration, channel and language facts.

Facts are one JSON object (MediaFacts v1). Keys are dotted paths. Pass several files and they merge; the same key with two different values is an error, so a stale measurement can't quietly win.

{"audio": {"integrated_lufs": -23.1, "true_peak_dbtp": -1.6, "duration_s": 1800.0},
 "video": {"duration_s": 1800.0},
 "av": {"offset_ms": 12.0},
 "captions": {"languages": ["en", "es"]}}

av.offset_ms is positive when audio is late.

The delivery spec

version: 1
profiles: [ebu_r128, ebu_r37_av_sync]     # built-ins, listed below
rules:
  - id: tracks_match
    path: audio.duration_s
    op: approx            # gte gt lte lt eq ne between approx in not_in present superset subset
    ref: video.duration_s # compare to another fact instead of a constant
    tol: 0.1
    severity: error       # info | warning | error | critical
  - id: captions
    path: captions.languages
    op: superset
    value: [en, es]
disable: [ebu_r128.true_peak]            # opt out of one profile rule, by id
waivers:
  - rule: ebu_r128.integrated_loudness
    reason: "remaster ticket MED-123"
    expires: 2026-12-31                  # required; an expired waiver stops waiving

Behavior worth knowing:

  • Unmeasured is not passed. A missing or non-numeric fact is an ERROR by default (on_missing: warning|skip per rule to change it). Booleans, strings and NaN are never numbers.
  • Typos fail loudly. An unknown op, field, profile or duplicate id raises. A rule is never silently dropped.
  • Waivers are visible. A waived finding becomes a non-gating INFO in the report and receipt. Expired waivers gate again and warn; a waiver for a rule that doesn't exist warns as stale.
  • Empty specs warn. A spec with no active rules cannot grade a clean PASS.
  • Numbers compare as numbers. 48000 and 48000.0 are equal for eq, ne, in and not_in. true is never 1.
  • Null is not measured. A null fact counts as missing. Booleans are never numbers, and true is not 1.
  • Bind the facts to the file. verel-ci media --asset masters/ep.mxf hashes the asset into the receipt, and if your facts carry asset.sha256 it must match, otherwise the finding is CRITICAL. Without --asset, nothing ties a facts file to a particular asset.
  • Specs are data, not programs. YAML anchors and aliases are rejected, and eq/in values must be scalars.

Built-in profiles

Profile Rules Source
ebu_r128 -23.0 LUFS +/-0.5 LU; true peak <= -1 dBTP EBU R 128 (standard)
atsc_a85 -24 LKFS +/-2 dB; true peak <= -2 dBTP ATSC A/85 (standard)
ebu_r37_av_sync audio <= 40 ms early, <= 60 ms late EBU R 37 (standard)
streaming_14, podcast_16 -14 / -16 LUFS +/-1; true peak <= -1 dBTP platform conventions, not standards

Profiles are a starting point, not a certification. Individual broadcasters and platforms publish their own delivery specs. Declare yours.

Content credentials (C2PA)

verel-ci provenance --repo . --asset masters/ep-2041.mp4 --policy provenance.yaml
verel-ci provenance --repo . --manifest-json ep-2041.c2pa.json      # fully offline, from a saved report

version: 1
require_manifest: true
trusted_issuers: ["Example News Org"]   # empty = don't restrict by issuer name
require_trusted_credential: false       # true = the library must report a TRUSTED state (merely "valid" fails)
ai_generated: flag                      # allow | flag (WARN, human review) | deny (FAIL)

Informational codes (ocsp.skipped, ocsp.inaccessible: revocation could not be checked) produce a WARNING, and success codes (...validated, ...match, ...trusted, ocsp.notRevoked) never count against an asset. Every other code is a failure.

A C2PA implementation (the c2patool binary, or pip install "verel[provenance]") validates the manifest, signature and hashes. Verel grades the result: no manifest, validation failure (tamper, CRITICAL), untrusted credential, issuer not allowed, AI-generated per digitalSourceType. If no backend is available the grader fails closed. Failure codes always win over a declared state, so a report that lists a tamper code is invalid even if it also says "Valid". --manifest-json is trusted input (anyone can hand-write one); add --asset to bind the saved report to the exact file bytes in the receipt.

Real output

python examples/demo_media.py (= verel media demo; synthetic facts, no key):

1. delivery as submitted: FAIL
    error    ebu_r128.integrated_loudness: -17.4 violates between [-23.5, -22.5]: integrated loudness must be -23.0 +/- 0.5 LU
    error    ebu_r128.true_peak: 0.8 violates lte -1.0: true peak must be <= -1.0 dBTP
    error    ebu_r37_av_sync.av_offset: 95.0 violates between [-40.0, 60.0]: audio must be no more than 40 ms early nor 60 ms late 
    error    tracks_match: 1800.0 violates approx 1802.5: audio.duration_s approx 1802.5
    error    captions: ["en"] violates superset ["en", "es"]: captions.languages superset ["en", "es"]
2. after remix, re-sync, Spanish captions: PASS
3. credentials, untouched: PASS
    info     manifest report is unverified input: it is not tied to any asset
4. credentials, bytes changed after signing: FAIL
    critical content credentials FAILED validation (tampered or corrupt): assertion.datahash.mismatch
    info     manifest report is unverified input: it is not tied to any asset

Honest limits

  • Verel grades supplied facts. If a sensor measures wrongly, Verel faithfully grades the wrong number.
  • Receipts bind the facts, the spec and the verdict. They do not prove the measurement was honest.
  • No manifest does not mean fake: most real media carries none. A valid manifest proves who signed and that bytes are unchanged since, not that the content is true. Verel does not detect deepfakes.
  • C2PA reader adapters were tested against fixtures in the c2patool JSON shape, not yet against a corpus of live signed assets from each vendor. Pilot on your real files before relying on it.