com.originalpictures.chromaprint.1

Identity

Pinned artefacts

Every file the runtime loads or builds from is pinned by SHA-256; a file with any other hash is refused.

How the fingerprint is computed

Chromaprint 1.6.1's fpcalc computes the raw 32-bit sub-fingerprints (algorithm 2) of the first 120 seconds of the audio.

How matching works

A candidate matches when its best alignment, shifted by at most 30 sub-fingerprints, has an aligned bit score of at least 0.75. A fingerprint is compared only with fingerprints of the same algorithm, calibration and threshold, within the account that signed the file. Strong on codecs, noise and re-recording; breaks under pitch or tempo change.

What a positive result means

A match means the file looks or sounds like a file the signer's account signed, closely enough to pass the threshold above. It points to that file's C2PA manifest, which declares its origin. It is a probabilistic lead, not cryptographic proof: a fingerprint matches similar content, can miss heavily edited copies, and says nothing about whether the content is true. The signed manifest, where it survives, is the proof.

Measured performance

Original Pictures' 2026 fingerprint benchmark measured this fingerprint at a different threshold from the one production matches at, so no figure is published for the production rule.

The value a soft-binding assertion would carry

• Value: The raw sub-fingerprints as little-endian 32-bit integers, as base64: the bytes Original Pictures stores, which fpcalc -raw also prints as numbers.
• Scope: A timespan: the first 120 seconds, or the whole file if shorter.
• Encoding note: The C2PA schema defines a soft-binding value as a byte string. Original Pictures' signing engine writes it as text, as it already does for the ISCC binding, so the form above is the text a manifest would carry.
• Emission: Planned after the identifier is assigned.

How to check a file

• Content Credentials. Any C2PA-aware validator can read and check the manifest of a file that still carries one, without calling Original Pictures.
• The fingerprint. Fingerprint recovery runs inside a verification: POST /v1/verifications on the Original Pictures API. When no manifest can be read, the verification compares the file's fingerprints with the recorded ones and reports a single match as recovery-only (VALIDATION_RECOVERY_ONLY), never as cryptographic validity; several plausible matches fail closed as ambiguous. Recovery searches only the bindings of the account that runs the verification. See lookup and recovery and fingerprints.
• There is no public soft-binding resolution API. A third party can check a file on the signer's hosted verify page, if the signer publishes one; that page searches the signer's own fingerprints only when the signer has switched recovery on (recover_own_assets). Otherwise, contact the signer or us.
• Comparing values yourself. Chromaprint is public, so once the value is in a manifest anyone can run fpcalc -raw on a candidate and compare.

Relation to C2PA

When a fingerprint algorithm has an identifier on the C2PA soft-binding algorithm list, the manifest can carry a c2pa.soft-binding assertion that names it in its alg field. Registration for com.originalpictures.chromaprint.1 has been requested with the C2PA soft binding algorithm list; no identifier has been assigned yet. Until one is, and until Original Pictures ships the change that writes it, no manifest names this fingerprint: it is a server-side recovery signal only. Today the one fingerprint a manifest carries is ISCC Image-Code (io.iscc.v0). This page is the entry's informational URL.

Status and contact

• Status: registration requested with the C2PA soft binding algorithm list.
• Contact: hello@originalpictures.com
• Last updated: 2026-11-08. The values on this page are generated from the production registry.
• All Original Pictures soft-binding algorithms