Watermarking protocol · v1 · 32-bit hash · 20-byte envelope
Mivia Sign writes a cryptographic watermark directly into the DCT coefficients of your audio. Inaudible. Robust to re-encoding. Byte-preserving on MP3. Timestamp-anchored to Bitcoin.
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A typical 3-minute stereo track at 44.1 kHz is 8.9 million samples per channel. Mivia Sign treats it as a stream of independent frames — 4096 samples each, 93 ms of audio at the engine's 22,050 Hz working rate.
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Each frame carries the full watermark payload independently. Every frame is a fresh chance to recover the signature — so even aggressively cropped audio still verifies, as long as one complete frame survives.
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The frame goes through a discrete cosine transform, splitting it into 2,048 frequency coefficients. Human hearing is most sensitive to mid-range frequencies — so the watermark skips those and hides in the perceptually quiet bands above.
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A blake3-derived master key picks which coefficients hold the watermark — roughly 120 bins out of the 2,048. Without the key, even a forensic listener can't find them; with the key, extraction is O(1) per frame.
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Each carrier coefficient is nudged to the nearest point on a quantisation lattice with spacing δ = 0.002. That's about −54 dBFS — below the noise floor of any practical listening environment, and well below the threshold of audibility.
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The 20 bytes embedded into every frame: a magic byte, a format version, a 4-byte issuer fingerprint, an 8-byte content hash pointing at the full manifest in the content-addressed store, a random nonce, and a 16-bit CRC. BCH-coded into 70 bytes before embedding so majority-vote recovery tolerates up to 40 bit errors per frame.
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The output is byte-identical to your input except for the imperceptible modifications inside the DCT coefficients. WAV stays WAV at the same sample rate and bit depth. MP3 stays MP3 at the same bitrate with the same frame count. Nothing about the file's identity, structure, or listening experience changes — except that it now carries your signature.
−54 dBFS
Peak distortion
Inaudible on any consumer playback system. Below the masking threshold of any non-silent program material.
20 bytes
Payload per frame
Magic, version, issuer, contract hash, nonce, CRC. Every frame carries the complete signature.
0 bytes
MP3 size change
Compressed-domain scalefactor editing. The file is byte-identical outside of the bits we intentionally flip.
40 bits
Error-correction headroom
BCH(1023, 463) ECC. Tolerates heavy re-encoding, noise addition, and bit-level corruption before a frame fails.
BTC
Timestamp anchoring
OpenTimestamps proof registered at sign time. Independently verifiable proof-of-existence backed by Bitcoin consensus.
v1
Frozen forever
The v1 algorithm bundle is locked via CI-gated constants. Every signed file works forever regardless of how the protocol evolves.