# AcoustID

## Overview

AcoustID is an open-source audio fingerprinting service. It identifies music tracks by their acoustic fingerprint and links them to MusicBrainz recordings.

## Key Features

- **Purpose**: Audio identification via acoustic fingerprinting
- **Technology**: Chromaprint fingerprint generation
- **Database**: Crowdsourced fingerprints linked to MusicBrainz
- **License**: MIT (code), CC BY-SA 3.0 (data)

## Source

| Resource | URL |
|----------|-----|
| **Server Repository** | https://github.com/acoustid/acoustid-server |
| **Index Repository** | https://github.com/acoustid/acoustid-index |
| **Chromaprint Library** | https://github.com/acoustid/chromaprint |
| **API Documentation** | https://acoustid.org/webservice |
| **Website** | https://acoustid.org |

## API Examples

```bash
# Lookup by fingerprint
GET /v2/lookup?client=YOUR_API_KEY&meta=recordings&fingerprint={fp}&duration={dur}

# Submit new fingerprint
POST /v2/submit
```

## Chromaprint CLI

```bash
# Generate fingerprint from audio file
fpcalc song.mp3
# Returns: FINGERPRINT=... DURATION=...
```

## Self-Hosting

The acoustid-index v2 is written in Zig for performance:

```bash
git clone https://github.com/acoustid/acoustid-index.git
# Follow build instructions in README
```

## Notes

- Used by: Beets, Picard, Kid3, MusicBrainz ecosystem
- Free API for audio fingerprint matching
- Identify unknown files → get MusicBrainz metadata