bpm4b 2.0.0

MP3 to M4B Audiobook Converter - Convert MP3 files to M4B format with chapter support

MP3 to M4B Audiobook Converter (bpm4b)

A Flask-based web application for converting MP3 files to M4B audiobook format with chapter support.

Install and run with: pip install bpm4b then bpm4b

Features

MP3 to M4B Converter

• Upload MP3 files
• Add custom chapter markers with titles and timestamps
• Automatically converts to M4B format (iTunes/Apple Books compatible)
• Uses FFmpeg for high-quality AAC audio (64kbps)
• Simple web interface

Prerequisites

• Python 3.8+
• FFmpeg (required for MP3 to M4B conversion)

Installing FFmpeg

Windows:

1. Go to https://www.gyan.dev/ffmpeg/builds/ (recommended Windows builds)
2. Download "ffmpeg-git-full.7z" or "ffmpeg-release-full.7z"
3. Extract the archive using 7-Zip or similar
4. Open the extracted folder, navigate to the bin folder
5. Copy the path to the bin folder (contains ffmpeg.exe)
6. Add to PATH:
   • Press Win + X, select "System"
   • Click "Advanced system settings"
   • Click "Environment Variables"
   • Under "System variables", find and select "Path", click "Edit"
   • Click "New" and paste the path to the bin folder
   • Click OK on all windows
7. Open a new command prompt and verify: ffmpeg -version

macOS:

brew install ffmpeg

Ubuntu/Debian:

sudo apt-get update
sudo apt-get install ffmpeg

Note: The MP3 to M4B conversion requires FFmpeg. Without it, the converter will not work.

Usage

Web Interface

Start the web server and open your browser to http://localhost:5000:

# Start the server
bpm4b web

# Or with custom options
bpm4b web --port 8080
bpm4b web --host 127.0.0.1 --debug

The web interface allows you to:

• Upload MP3 files through a simple form
• Add custom chapter markers with titles and timestamps
• Download the converted M4B audiobook

Command Line (No Web Interface)

Convert MP3 to M4B directly from the terminal:

# Basic conversion
bpm4b convert input.mp3 output.m4b

# With chapter markers
bpm4b convert input.mp3 output.m4b --chapter "Introduction" 0
bpm4b convert input.mp3 output.m4b --chapter "Chapter 1" 3600 --chapter "Chapter 2" 7200

# Multiple chapters
bpm4b convert book.mp3 book.m4b \\
  --chapter "Prologue" 0 \\
  --chapter "Chapter 1" 300 \\
  --chapter "Chapter 2" 1800

# Multiple chapters with MM:SS format
bpm4b convert book.mp3 book.m4b \\
 --chapter "Prologue" "0:00" \\
 --chapter "Chapter 1" "5:00" \\
 --chapter "Chapter 2" "30:00"

# Mixed formats (seconds and MM:SS)
bpm4b convert book.mp3 book.m4b \\
 --chapter "Intro" 0 \\
 --chapter "Chapter 1" "6:30" \\
 --chapter "Chapter 2" 3600

Chapter start times accept:

• Seconds as integer (e.g., 390)
• Minutes:seconds format (e.g., "6:30" or "6:30.5" for fractional seconds)

Using Python Module

Alternatively, you can run it as a Python module:

python -m bpm4b.cli web --port 5000
python -m bpm4b.cli convert input.mp3 output.m4b

Using the CLI (Package Installation)

After installing with pip install -e ., use the bpm4b command:

# Start web interface
bpm4b web

# Web interface with options
bpm4b web --port 8080
bpm4b web --host 127.0.0.1 --debug

# Convert MP3 to M4B directly
bpm4b convert input.mp3 output.m4b
bpm4b convert input.mp3 output.m4b --chapter "Chapter 1" 0

# Show help
bpm4b --help
bpm4b web --help
bpm4b convert --help

Using Python Module

Alternatively, you can run it as a Python module:

python -m bpm4b.cli web --port 5000
python -m bpm4b.cli convert input.mp3 output.m4b

Using the Traditional Method

If you installed dependencies only (without the package):

python app.py

Then open your browser and navigate to:

http://localhost:5000

Using the Tool

Once the server is running:

MP3 to M4B: Upload an MP3 file, optionally add chapter markers, and click "Convert to M4B"

• Automatically converts to M4B format (iTunes/Apple Books compatible)
• Add custom chapter titles and timestamps
• Uses FFmpeg for high-quality AAC audio (64kbps)

API Endpoints

POST /api/mp3-to-m4b

Converts an MP3 file to M4B with optional chapters.

Form Data:

• mp3_file: The MP3 file to convert
• chapters (optional): JSON array of chapter objects. start_time accepts seconds (number) or MM:SS format (string):

[
  {"title": "Chapter 1", "start_time": 0},
  {"title": "Chapter 2", "start_time": "6:30"},
  {"title": "Chapter 3", "start_time": 3600}
]

Response: Returns an M4B file as a download.

Project Structure

.
├── bpm4b/              # Main package directory
│   ├── __init__.py    # Package initialization
│   ├── app.py         # Flask application (for local development)
│   ├── cli.py         # Command-line interface entry point
│   ├── core.py        # Shared core functions
│   ├── api/
│   │   ├── __init__.py
│   │   └── index.py   # Vercel serverless function
│   └── templates/
│       └── index.html # Frontend interface
├── setup.py           # Package installation configuration
├── vercel.json        # Vercel configuration
├── requirements.txt   # Python dependencies
├── uploads/           # Temporary uploaded files (created automatically)
├── outputs/           # Generated files (created automatically)
└── README.md          # This file

Notes

• Maximum file size for uploads: 100MB
• Temporary files are cleaned up automatically
• M4B output files can be large (typically 0.96-2GB per hour of audio depending on bitrate)
• The default audio bitrate is 64kbps AAC, which provides good quality for speech

License

MIT