---
title: "Video Fingerprinting"
description: "
"
url: https://instituteofprovenance.org/docs/video-fingerprinting
source: Institute of Provenance
---
# Video Fingerprinting

Video fingerprinting extends the Institute's perceptual fingerprinting approach to temporal media through dual-track visual and audio waveform analysis with hierarchical aggregation.

## Dual-Track Architecture

Video contains two independent signal tracks that must be analyzed separately and then correlated:

### Visual Track

The visual track applies LWA principles to video frames:

1. **Frame sampling** — Extract frames at a configurable rate (default: 2 fps for fingerprinting, higher for forensic analysis)
2. **Per-frame LWA** — Apply Luminance Waveform Analysis to each sampled frame, producing per-frame spectral features
3. **2D FFT analysis** — Apply 2D Fast Fourier Transform to capture spatial frequency content across the full frame
4. **Temporal aggregation** — Aggregate per-frame features using a hierarchical scheme: frame-level features roll up into shot-level features, which roll up into a video-level fingerprint

### Audio Track

The audio track uses spectral analysis methods from audio fingerprinting research:

1. **STFT computation** — Short-Time Fourier Transform of the audio signal with overlapping windows
2. **MFCC extraction** — Mel-Frequency Cepstral Coefficients capture the spectral envelope of the audio signal
3. **Temporal features** — Energy contour, onset detection, and rhythmic features provide temporal structure
4. **Aggregation** — Audio features are aggregated at the same temporal granularity as visual features

## A/V Synchronization Analysis

A key forensic capability is detecting audio-video synchronization anomalies:

- **Temporal alignment** — Verify that audio events (speech, impacts, music beats) align with corresponding visual events
- **Drift detection** — Identify gradual A/V desynchronization that may indicate splicing or speed manipulation
- **Gap detection** — Identify temporal gaps where audio or video has been removed

A/V sync anomalies are strong indicators of manipulation, as most editing operations affect audio and video independently, creating detectable misalignment.

## Temporal Coherence Scoring

The temporal coherence score measures how consistently visual and audio features evolve over time. Natural video exhibits characteristic temporal patterns:

- Scene transitions produce predictable feature discontinuities
- Camera motion produces smooth feature evolution within shots
- Audio follows the visual narrative with characteristic correlation patterns

Manipulated video disrupts these patterns. The coherence score quantifies the degree of disruption, providing a per-segment confidence measure.

## Speed Manipulation Detection

Speed changes (slow motion, fast forward, time-lapse) are detected through:

- **Frame rate analysis** — Statistical analysis of inter-frame differences to detect non-uniform temporal sampling
- **Audio pitch analysis** — Speed changes shift audio pitch unless pitch correction is applied; both the shift and the correction artifacts are detectable
- **Motion consistency** — Unnatural acceleration/deceleration patterns in visual motion vectors

## Hierarchical Fingerprint Structure

The video fingerprint is organized hierarchically:

```
Video Fingerprint
├── Visual Track
│   ├── Shot 1
│   │   ├── Frame features (LWA + 2D FFT)
│   │   └── Shot-level aggregate
│   ├── Shot 2
│   │   └── ...
│   └── Video-level visual aggregate
├── Audio Track
│   ├── Segment 1
│   │   ├── STFT + MFCC features
│   │   └── Segment-level aggregate
│   ├── Segment 2
│   │   └── ...
│   └── Video-level audio aggregate
└── A/V Correlation Features
```

This structure enables matching at multiple granularities — a short clip can be matched against a full video by comparing shot-level or segment-level features.

## Storage as XFPR Records

Video fingerprints are stored as XFPR records with `fingerprint_type: "video-lwa"`. The hierarchical structure is serialized into the `fingerprint_data` field, enabling both full-video and partial-video queries through the wire protocol.