LibreToM4b

A command-line tool to convert audiobooks downloaded with LibreGrab into M4B audiobook format.

Features

• MP3 to M4B Conversion: Concatenates multiple MP3 files into a single M4B audiobook file
• Automatic Chapter Detection: Parses LibreGrab metadata to preserve chapter markers
• Metadata Preservation: Extracts and embeds title, author, narrator, and description
• Fallback Metadata: Generates metadata from ID3 tags when LibreGrab metadata is unavailable
• Progress Reporting: Visual progress bar during conversion
• Configurable Output: Custom output directory support

Prerequisites

• .NET 10.0 SDK or later
• FFmpeg installed and available in PATH

Installation

# Clone the repository
git clone https://github.com/clFaster/LibreToM4b.git
cd LibreToM4b

# Build the project
dotnet build

# Run the tool
dotnet run --project LibreToM4b -- convert <input-folder>

Usage

# Basic usage - converts audiobook to default output folder (Music/LibreToM4b)
LibreToM4b convert <input-folder>

# With custom output folder
LibreToM4b convert <input-folder> --output <output-folder>
LibreToM4b convert <input-folder> -o <output-folder>

Arguments

Argument	Description
input-folder	Path to the folder containing MP3 files from LibreGrab

Options

Option	Short	Description
--output	-o	Output folder for the M4B file (default: Music/LibreToM4b)

Input Folder Structure

The input folder should contain:

audiobook-folder/
├── 001.mp3
├── 002.mp3
├── ...
└── metadata/
    └── metadata.json    (optional - LibreGrab metadata)

Project Structure

LibreToM4b/
├── LibreToM4b.Core/     # Core library with models and services
│   ├── Models/          # Data models (Book, Chapter, etc.)
│   ├── Services/        # Conversion service logic
│   └── Interfaces/      # Service abstractions
└── LibreToM4b/          # CLI application
    └── Commands/        # Command-line command handlers

License

This project is licensed under the MIT License - see the LICENSE file for details.