# Audio Offset Tool

Finds the time offset between a local audio file and a YouTube video's audio using Chromaprint fingerprint matching. Generates stereo comparison WAV files for ear verification.

## Prerequisites

### ffmpeg

```bash
# macOS
brew install ffmpeg

# Ubuntu/Debian
sudo apt install ffmpeg

# Windows (via scoop)
scoop install ffmpeg
```

### fpcalc (Chromaprint)

```bash
# macOS
brew install chromaprint

# Ubuntu/Debian
sudo apt install libchromaprint-tools

# Windows
# Download from https://acoustid.org/chromaprint — extract and add to PATH
```

### Python dependencies

```bash
pip install -r requirements.txt
```

## Usage

```bash
# Basic usage
python find_offset.py ../../public/songs/get-lucky/audio.ogg 5NV6Rdv1a3I

# Video IDs starting with '-'
python find_offset.py ../../public/songs/meet-me-halfway/audio.ogg --yt=-GY8MhHMxLM

# Custom output directory
python find_offset.py ../../public/songs/get-lucky/audio.ogg 5NV6Rdv1a3I --out-dir ./my-compare

# JSON output (for scripting)
python find_offset.py ../../public/songs/get-lucky/audio.ogg 5NV6Rdv1a3I --json
```

## Output

The tool prints candidate offsets ranked by fingerprint similarity and writes stereo WAV files to the output directory.

Listen to each WAV with headphones:
- **Left ear** = local audio
- **Right ear** = YouTube audio (shifted by candidate offset)

The file where both ears are in sync has the correct offset.