# ExifTool Setup Guide

ExifTool is a powerful command-line application for reading, writing, and editing metadata in a wide variety of files. Oliver Metadata Tool uses ExifTool to provide enhanced metadata support for 300+ file formats.

## Why ExifTool?

- **Unified API**: Single tool handles images, videos, PDFs, and more
- **300+ formats**: Support for virtually all media file types
- **Better performance**: Optimized batch operations (10-60x faster)
- **Battle-tested**: 20+ years of development and widespread use
- **PDF writing support**: Can write PDF metadata (unlike pypdf)

## Installation

### macOS

```bash
brew install exiftool
```

Verify installation:
```bash
exiftool -ver
# Should show version 12.15 or higher
```

### Linux (Ubuntu/Debian)

```bash
sudo apt-get update
sudo apt-get install libimage-exiftool-perl
```

Verify installation:
```bash
exiftool -ver
```

### Linux (Fedora/RHEL/CentOS)

```bash
sudo yum install perl-Image-ExifTool
```

### Windows

**Option 1: Chocolatey**
```powershell
choco install exiftool
```

**Option 2: Manual installation**
1. Download from https://exiftool.org/
2. Extract the `.zip` file
3. Rename `exiftool(-k).exe` to `exiftool.exe`
4. Add the directory to your PATH

Verify installation:
```powershell
exiftool -ver
```

## Verification

After installation, verify ExifTool is accessible:

```bash
# Check version
exiftool -ver

# Check location
which exiftool  # macOS/Linux
where exiftool  # Windows

# Test with a file
exiftool your-image.jpg
```

## What Oliver Metadata Tool Uses ExifTool For

### Supported Operations

1. **Images (JPEG, PNG, GIF, TIFF, HEIC, RAW formats)**
   - Read/write Title, Description, Keywords
   - Access EXIF, IPTC, XMP metadata
   - Support for camera metadata

2. **Videos (MP4, MOV, AVI, MKV)**
   - Read/write Title, Description, Keywords
   - QuickTime metadata support
   - Unified API across formats

3. **PDFs**
   - Read/write PDF metadata fields
   - Better than pypdf for metadata writing
   - Preserves document structure

### Format Coverage

ExifTool provides support for these additional formats beyond Python libraries:

- **Images**: HEIC, CR2, NEF, ARW, DNG (RAW formats)
- **Video**: MKV, WebM, FLV, WMV (extended video formats)
- **Audio**: MP3, FLAC, WAV, OGG (audio files)
- **Documents**: EPUB, MOBI (ebook formats)
- **3D/CAD**: STL, DWG, DXF
- And 250+ more formats

## PyExifTool Python Wrapper

Oliver Metadata Tool uses the PyExifTool library to interact with ExifTool from Python:

```python
from exiftool import ExifToolHelper

# Read metadata
with ExifToolHelper() as et:
    metadata = et.get_metadata(["image.jpg"])
    print(metadata[0])

# Write metadata
with ExifToolHelper() as et:
    et.set_tags(
        ["image.jpg"],
        tags={"EXIF:ImageDescription": "New Title"},
        params=["-overwrite_original"]
    )
```

### Batch Mode Performance

PyExifTool uses ExifTool's `-stay_open` mode, which keeps one ExifTool process running for multiple operations:

- **Single file operations**: ~50-100ms overhead
- **Batch operations (100 files)**: 10-60x faster than spawning new processes
- **Memory efficient**: One process handles all operations

## Troubleshooting

### ExifTool not found

**Error:** `ExifTool not found` or `exiftool command not available`

**Solution:**
1. Install ExifTool using the instructions above
2. Restart your terminal/command prompt
3. Verify with `exiftool -ver`
4. If still not found, check your PATH environment variable

### Permission denied

**Error:** `Permission denied when executing exiftool`

**Solution (macOS/Linux):**
```bash
chmod +x /path/to/exiftool
```

### PyExifTool import error

**Error:** `ModuleNotFoundError: No module named 'exiftool'`

**Solution:**
```bash
pip install PyExifTool>=0.5.6
```

### Encoding issues with Unicode filenames

ExifTool handles Unicode filenames natively. If you encounter issues:

1. Ensure your terminal supports UTF-8
2. Use the PyExifTool wrapper (handles encoding automatically)
3. Check file system supports Unicode filenames

## Performance Tips

### Use batch mode for multiple files

```python
# Good: Process multiple files in one batch
with ExifToolHelper() as et:
    et.set_tags(
        ["file1.jpg", "file2.jpg", "file3.jpg"],
        tags={"EXIF:ImageDescription": "Title"},
        params=["-overwrite_original"]
    )

# Avoid: Processing files one at a time
for file in files:
    with ExifToolHelper() as et:
        et.set_tags([file], tags={...})
```

### Use specific tag names

```python
# Good: Specific tag queries
et.get_tags(["image.jpg"], tags=["EXIF:ImageDescription", "XMP:Title"])

# Slower: Extract all tags
et.get_metadata(["image.jpg"])  # Returns 100+ tags
```

### Skip unnecessary tags with -fast

For read-only operations where you only need basic metadata:

```python
et.execute("-fast", "-json", "image.jpg")
```

## Integration with Oliver Metadata Tool

Oliver Metadata Tool automatically detects ExifTool and uses it when available:

1. **On startup**: Checks for ExifTool installation
2. **Hybrid approach**: Uses ExifTool for images/video/PDF, Python libraries for Office docs
3. **Graceful fallback**: Falls back to pure Python if ExifTool unavailable

### Check ExifTool status

```python
from src.config import Config

if Config.check_exiftool():
    print("ExifTool available")
else:
    print("Using Python libraries")
```

## References

- [ExifTool Official Website](https://exiftool.org/)
- [ExifTool Documentation](https://exiftool.org/exiftool_pod.html)
- [PyExifTool GitHub](https://github.com/sylikc/pyexiftool)
- [PyExifTool Documentation](https://sylikc.github.io/pyexiftool/)
- [Supported File Types](https://exiftool.org/#supported)
- [Tag Names Reference](https://exiftool.org/TagNames/)

## License

ExifTool is free software licensed under the Perl Artistic License or GPL version 1 or later.