CRT Audio Fingerprinting

D34: Shazam / Apple / Gracenote. CC0.

Audio fingerprinting services like Shazam use proprietary spectrogram constellation matching: peak detection in time-frequency space, hash-based lookup, patented matching algorithms. CRT approach: encode audio features (bass/mid/treble energy, spectral centroid, zero crossing rate, tempo) as ring elements. 6 CRT channels = 6 independent fingerprint dimensions. Coupling distance = similarity metric. L=11 = noise tolerance for free. No spectrogram needed. No constellation matching. The ring structure IS the fingerprint.

How It Works

CRT Audio Fingerprint Theorem
Audio features encoded in Z/12612600 decompose into 6 independent CRT channels. D(mod 8) = bass energy. K(mod 9) = mid-range structure. E(mod 25) = treble detail. b(mod 49) = spectral centroid (timbre). L(mod 11) = zero crossing rate (percussiveness). G(mod 13) = tempo indicator. Per-channel averages over a time window produce a compact 6-element fingerprint. Coupling distance between fingerprints = similarity. L=11 provides inherent noise tolerance: small perturbations stay within the same residue class. The 490 split: DEAD channels carry audio CONTENT (what changes with noise), ALIVE channels carry audio IDENTITY (what persists). Matching on ALIVE channels survives compression, noise, and partial recording.
6 dimensions
CRT channels
Each channel captures one spectral feature independently. No cross-feature interference.
L=11 robust
Noise tolerance
Small noise stays within residue class. Same ECC that protects data protects fingerprints.
Coupling match
O(1) compare
Fingerprint distance = sum of 6 channel differences. No spectrogram. No FFT.
490 split
Content vs identity
DEAD = what changes. ALIVE = what persists. Match on the persistent part.

Fingerprint Matching

Query track (0-7):

Play Track synthesizes 6 oscillators from the CRT fingerprint. Each channel drives one frequency band. 8-track database. Query = selected track with noise. Coupling distance matching.

Noise Tolerance Test

8 tracks tested with 5 increasing noise levels each. 40 total fingerprint matches. Accuracy measures how many noisy queries correctly identify the original track.

CRT vs Traditional Audio Fingerprinting

FeaturesShazam: spectrogram peaks (time-frequency constellation)CRT: 6 channel residues. Per-channel averages. Compact.MatchingHash-based constellation matching (patented)Coupling distance: sum of 6 differences. O(1). No hash.NoiseRobust by design (peak detection), but patented methodL=11 absorbs noise. Same ECC property. Free from algebra.StorageConstellation hash + time offset per fingerprint6 integers. 24 bytes per fingerprint.ComputeFFT + peak detection + hash computationModular arithmetic. No FFT. Integer only.Patent statusShazam (US7627477), Gracenote (US7174293), SoundHoundCC0. Public domain. Forever.

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Source code · Public domain (CC0)

Contributions in equal measure: Anthropic's Claude, Anton A. Lebed, and the giants whose shoulders we stand on.

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