Audiobook Forge 🎧

A blazing-fast CLI tool for converting audiobook directories to M4B format with chapters and metadata. Written in Rust for maximum performance and reliability.

📑 Table of Contents

Why Audiobook Forge?
Features
Installation
Dependencies
Usage
Configuration
Input Directory Structure
Supported Formats
Performance
Troubleshooting
Contributing
License
Acknowledgments

🎯 Why Audiobook Forge?

When downloading audiobooks, they often come as multiple separate MP3 files — one for each chapter or section. While this works perfectly fine with various audiobook players like AudiobookShelf and others, managing your audiobook library becomes significantly easier when each audiobook is consolidated into a single file.

Audiobook Forge solves this problem by taking those scattered audio files and merging them into a single M4B file (MPEG-4 Audiobook format), which has become the standard for audiobook applications and offers superior portability and management.

📚 Single File vs. Multiple Files: The Benefits

With a single M4B file, you get:

✅ Simplified Library Management

One file per audiobook instead of dozens or hundreds of individual files
Easier to organize, rename, move, and backup
Cleaner directory structure

✅ Better Metadata & Chapter Support

Embedded chapter markers for easy navigation
Complete metadata (title, author, narrator, cover art) in one place
Chapter information persists across devices and players

✅ Improved Portability

Transfer entire audiobooks with a single file copy
Sync seamlessly across devices (phone, tablet, computer)
No risk of missing files or broken chapter sequences

✅ Enhanced Playback Experience

Resume exactly where you left off, even across different apps
Navigate chapters with built-in chapter markers
Cover art displays properly in all compatible players

✅ Reduced Storage Overhead

Eliminates file system overhead from multiple small files
Efficient compression while preserving audio quality
Optional copy mode for instant merging without re-encoding

✅ Universal Compatibility

M4B format supported by Apple Books, Audiobookshelf, Plex, and most modern audiobook players
Works across iOS, Android, macOS, Windows, and Linux
Industry-standard format for audiobook distribution

✨ Features

📁 Auto-Detect Current Directory: Run from inside audiobook folders without --root parameter
⚡ Parallel File Encoding: Encode files concurrently for 3.8x faster processing (121s → 32s)
🚀 Parallel Book Processing: Convert multiple audiobooks simultaneously with intelligent resource management
🎯 Smart Quality Detection: Automatically detects and preserves the best audio quality
📖 Chapter Generation: Multiple sources (files, CUE sheets, auto-detection)
🎨 Metadata Management: Extracts and enhances metadata from ID3 and M4A tags
🎭 Interactive Metadata Matching (v2.4.1 - Enhanced, v2.4.0 - Fixed, v2.3.0 - Introduced): BEETS-inspired interactive matching system
- Fuzzy string matching with weighted scoring (Title 40%, Author 30%, Duration 20%, Year 10%)
- Color-coded confidence levels (Green >96%, Yellow 88-96%, Red 80-88%)
- Visual percentage display for each candidate
- Interactive selection with Skip/Manual Entry/Custom Search options
- Batch processing with progress tracking
- Auto mode for non-interactive matching
- Note: v2.4.0 fixed search functionality, v2.4.1 enhanced metadata extraction from filenames with underscores
🎧 Audible Metadata Integration (v2.2.0): Fetch comprehensive metadata from Audible's catalog
- Automatic ASIN detection from folder names
- 10 regional stores (US, CA, UK, AU, FR, DE, JP, IT, IN, ES)
- High-quality cover art download
- Smart caching (7-day default TTL)
- Rate-limited API integration
🖼️ Cover Art: Automatically detects and embeds cover images
🔄 Batch Operations: Process entire libraries with a single command
⚡ Copy Mode: Ultra-fast concatenation without re-encoding when possible
🎯 Smart Encoder Selection: Automatic AAC encoder detection with fallback (aac_at → libfdk_aac → aac)
🔁 Error Recovery: Automatic retry with configurable settings
📊 Progress Tracking: Real-time progress with ETA calculation
🗂️ Auto-Organization: Organize books into M4B and To_Convert folders
⚙️ Configuration: Comprehensive YAML-based configuration with CLI overrides

📦 Installation

Prerequisites

Rust 1.75+: Install from rustup.rs
FFmpeg: Required for audio processing
AtomicParsley: Required for metadata embedding
MP4Box (from GPAC): Required for M4B container creation

Via Cargo (Recommended)

cargo install --git https://github.com/juanra/audiobook-forge

From Source

# Clone the repository
git clone https://github.com/juanra/audiobook-forge
cd audiobook-forge

# Build and install
cargo build --release
cargo install --path .

# Or just build (binary at: target/release/audiobook-forge)
cargo build --release

🔧 Dependencies

Install the required external tools:

macOS

brew install ffmpeg atomicparsley gpac

Ubuntu/Debian

sudo apt update
sudo apt install ffmpeg atomicparsley gpac

Fedora/RHEL

sudo dnf install ffmpeg atomicparsley gpac

Verify Installation

audiobook-forge check

Expected output:

→ Checking system dependencies...

  ✓ FFmpeg
  ✓ AtomicParsley
  ✓ MP4Box

✓ All dependencies found

🚀 Usage

Quick Start

# Auto-detect: Run from inside an audiobook folder (NEW in v2.1.0!)
cd "/path/to/My Audiobook"
audiobook-forge build

# Or specify the root directory explicitly
audiobook-forge build --root "/path/to/My Audiobook"

# Process multiple audiobooks in parallel
audiobook-forge build --root "/path/to/audiobooks" --parallel 4

# Organize library (move M4B files to M4B/ folder)
audiobook-forge organize --root "/path/to/audiobooks"

Command Reference

`build` - Convert audiobooks to M4B

audiobook-forge build [OPTIONS]

Options:

--root <PATH> - Root directory containing audiobook(s) (optional; auto-detects current directory if omitted)
--parallel <N> - Number of parallel workers (default: CPU cores / 2)
--skip-existing - Skip audiobooks that already have M4B files (default: true)
--quality <PRESET> - Quality preset: low, medium, high, ultra, maximum, source (default: source)
- low - 64kbps, 22050Hz, mono (smallest file size)
- medium - 96kbps, 44100Hz, stereo (balanced quality/size)
- high - 128kbps, 48000Hz, stereo (premium audiobook quality)
- ultra - 192kbps, 48000Hz, stereo (for music/theatrical productions)
- maximum - 256kbps, 48000Hz, stereo (near-lossless quality)
- source - Auto-detect from source files (default)
--output <PATH> - Output directory (default: same as source)
-v, --verbose - Verbose logging

`organize` - Organize audiobook library

audiobook-forge organize [OPTIONS] --root <PATH>

Options:

--root <PATH> - Root directory to organize (required)
--dry-run - Show what would be done without making changes
-v, --verbose - Verbose logging

`match` - Interactive metadata matching (v2.4.1 - Enhanced, v2.4.0 - Fixed, v2.3.0 - Introduced)

audiobook-forge match [OPTIONS]

BEETS-inspired interactive matching - Search Audible and interactively select the best metadata match for M4B files with visual scoring and confidence levels.

Note: v2.4.0 fixed critical search API bug (404 errors). v2.4.1 enhanced metadata extraction to correctly parse filenames with underscores (e.g., Author_-_Title.m4b), dramatically improving match accuracy.

Required (one of):

--file <PATH> - Match single M4B file
--dir <PATH> - Match all M4B files in directory

Optional:

--title <TITLE> - Manual title override
--author <AUTHOR> - Manual author override
--auto - Auto-select best match (non-interactive)
--region <REGION> - Audible region (default: us)
--keep-cover - Keep existing cover art instead of downloading
--dry-run - Show matches but don't apply

Features:

🎯 Fuzzy string matching with weighted scoring (Title: 40%, Author: 30%, Duration: 20%, Year: 10%)
🎨 Color-coded confidence levels (Green: >96%, Yellow: 88-96%, Red: 80-88%)
📊 Visual percentage display for each candidate
🔄 Multiple options: Skip, Manual Entry, Custom Search
📝 Before/after metadata comparison
🚀 Batch processing with progress tracking

Examples:

# Interactive match single file
audiobook-forge match --file "Book.m4b"

# Batch process directory
audiobook-forge match --dir /path/to/audiobooks

# Auto mode (non-interactive)
audiobook-forge match --dir /path --auto

# Manual override
audiobook-forge match --file "Book.m4b" --title "Title" --author "Author"

# Dry run
audiobook-forge match --dir /path --dry-run

`metadata` - Fetch and manage Audible metadata (NEW in v2.2.0)

audiobook-forge metadata <SUBCOMMAND>

Subcommands:

fetch - Fetch metadata from Audible

audiobook-forge metadata fetch [OPTIONS]

--asin <ASIN> - Audible ASIN (e.g., B00B5HZGUG)
--title <TITLE> - Search by title
--author <AUTHOR> - Search by author
--region <REGION> - Audible region: us, uk, ca, au, fr, de, jp, it, in, es (default: us)
--output <PATH> - Save metadata to JSON file

enrich - Enrich M4B file with Audible metadata

audiobook-forge metadata enrich [OPTIONS]

--file <PATH> - M4B file to enrich
--asin <ASIN> - Audible ASIN
--auto-detect - Auto-detect ASIN from filename
--region <REGION> - Audible region (default: us)

Build Integration:

--fetch-audible - Enable Audible metadata fetching during build
--audible-region <REGION> - Specify Audible region for build
--audible-auto-match - Auto-match books by folder name

Examples:

# Fetch by ASIN
audiobook-forge metadata fetch --asin B00B5HZGUG

# Search by title/author
audiobook-forge metadata fetch --title "The Martian" --author "Andy Weir"

# Enrich existing M4B
audiobook-forge metadata enrich --file book.m4b --asin B00B5HZGUG

# Auto-fetch during build
audiobook-forge build --root /audiobooks --fetch-audible --audible-region us

See AUDIBLE_METADATA.md for comprehensive documentation.

`config` - Manage configuration

audiobook-forge config <SUBCOMMAND>

Subcommands:

init - Create default config file
show - Display current configuration
validate - Validate config file
path - Show config file location
edit - Open config in default editor

`check` - Verify dependencies

audiobook-forge check

Checks for FFmpeg, AtomicParsley, and MP4Box installation.

`--version` - Show version

audiobook-forge --version

Usage Examples

Example 1: Auto-Detect from Current Directory (NEW in v2.1.0!)

Directory structure:

~/Downloads/My Audiobook/
├── 01 - Introduction.mp3
├── 02 - Chapter One.mp3
├── 03 - Chapter Two.mp3
└── cover.jpg

Command:

cd ~/Downloads/My\ Audiobook
audiobook-forge build

Output:

→ Auto-detected audiobook folder: /Users/you/Downloads/My Audiobook
→ Scanning audiobooks in: /Users/you/Downloads/My Audiobook

✓ Found 1 audiobook(s)

→ Analyzing tracks...
✓ Analysis complete

→ Processing 1 audiobook(s)...

  ✓ My Audiobook (32.1s, transcode)

✓ Batch complete: 1 successful, 0 failed

Result:

~/Downloads/My Audiobook/
├── 01 - Introduction.mp3
├── 02 - Chapter One.mp3
├── 03 - Chapter Two.mp3
├── cover.jpg
└── My Audiobook.m4b  ← Created in the same directory!

Note: Auto-detect requires 2+ audio files (MP3/M4A) in the current directory.

Example 2: Convert a Single Audiobook (Explicit Path)

Directory structure:

/audiobooks/The Great Gatsby/
├── 01 - Chapter 1.mp3
├── 02 - Chapter 2.mp3
├── 03 - Chapter 3.mp3
├── cover.jpg
└── info.txt

Command:

audiobook-forge build --root "/audiobooks/The Great Gatsby"

Output:

Audiobook Forge v2.1.0

→ Discovering audiobooks...
  Found 1 audiobook to process

→ Processing: The Great Gatsby
  Case: B (MP3 files - requires conversion)
  Tracks: 3 files
  Quality: 128kbps, 44.1kHz, Stereo
  Duration: 4h 23m

  [00:02:15] ████████████████████ 100% | ETA: 0s

  ✓ Created: The Great Gatsby.m4b
  Size: 246 MB
  Time: 2m 15s

✓ Complete: 1 success, 0 failed

Result:

/audiobooks/The Great Gatsby/
├── 01 - Chapter 1.mp3
├── 02 - Chapter 2.mp3
├── 03 - Chapter 3.mp3
├── cover.jpg
├── info.txt
└── The Great Gatsby.m4b  ← New file

Example 3: Batch Convert Multiple Audiobooks

Directory structure:

/audiobooks/
├── Book 1/
│   ├── chapter1.mp3
│   └── chapter2.mp3
├── Book 2/
│   ├── part1.m4a
│   └── part2.m4a
└── Book 3/
    └── audiobook.m4b  (already converted)

Command:

audiobook-forge build --root /audiobooks --parallel 2

Output:

Audiobook Forge v2.1.0

→ Discovering audiobooks...
  Found 3 audiobooks (1 already converted, skipped)

→ Processing 2 audiobooks with 2 workers...

[Book 1] Case B: MP3 → M4B (transcode)
[Book 2] Case C: M4A → M4B (copy mode - fast!)

[Book 1] [00:01:30] ████████████████████ 100%
[Book 2] [00:00:15] ████████████████████ 100%

Results:
  ✓ Book 1.m4b - 156 MB (1m 30s)
  ✓ Book 2.m4b - 203 MB (15s) [copy mode]
  ⊘ Book 3 - Already exists (skipped)

✓ Complete: 2 success, 0 failed, 1 skipped
Total time: 1m 45s

Example 4: Organize Library

Before:

/audiobooks/
├── Book 1/
│   ├── chapter1.mp3
│   └── Book 1.m4b
├── Book 2/
│   ├── part1.mp3
│   └── Book 2.m4b
└── Book 3/
    ├── 01.mp3
    └── 02.mp3

Command:

audiobook-forge organize --root /audiobooks

Output:

→ Organizing audiobook library...

  Moving completed audiobooks to M4B/
  ✓ Book 1.m4b → M4B/Book 1.m4b
  ✓ Book 2.m4b → M4B/Book 2.m4b

  Organizing unconverted books to To_Convert/
  ✓ Book 3/ → To_Convert/Book 3/

✓ Organization complete
  2 M4B files moved
  1 folder moved to To_Convert

After:

/audiobooks/
├── M4B/
│   ├── Book 1.m4b
│   └── Book 2.m4b
└── To_Convert/
    └── Book 3/
        ├── 01.mp3
        └── 02.mp3

Example 5: Fetch Audible Metadata (NEW in v2.2.0)

Fetch metadata by ASIN:

audiobook-forge metadata fetch --asin B00B5HZGUG

Output:

→ Fetching Audible metadata...
  → Looking up ASIN: B00B5HZGUG

============================================================
Title: The Martian
Subtitle: null
Author(s): Andy Weir
Narrator(s): R. C. Bray
Publisher: Podium Publishing
Published: 2013
Duration: 10h 53m
Language: english
Genres: Science Fiction & Fantasy
ASIN: B00B5HZGUG
============================================================

Search by title and author:

audiobook-forge metadata fetch --title "Project Hail Mary" --author "Andy Weir" --region us

Enrich existing M4B file:

# With explicit ASIN
audiobook-forge metadata enrich --file "The Martian.m4b" --asin B00B5HZGUG

# Auto-detect ASIN from filename (e.g., "The Martian [B00B5HZGUG].m4b")
audiobook-forge metadata enrich --file "The Martian [B00B5HZGUG].m4b" --auto-detect

Auto-fetch during build (recommended workflow):

# Rename folders with ASINs for automatic detection
# Format: Book Title [B00G3L6JMS]

cd /audiobooks
mv "The Martian" "The Martian [B00B5HZGUG]"
mv "Project Hail Mary" "Project Hail Mary [B00G3L6JMS]"

# Build with Audible metadata
audiobook-forge build --root /audiobooks --fetch-audible --audible-region us

Output:

→ Scanning audiobooks in: /audiobooks
✓ Found 2 audiobook(s)

→ Analyzing tracks...
✓ Analysis complete

→ Fetching Audible metadata...
  ✓ The Martian (ASIN: B00B5HZGUG)
  ✓ Project Hail Mary (ASIN: B00G3L6JMS)
✓ Fetched metadata for 2/2 books

→ Processing 2 audiobook(s)...
  ✓ The Martian (32.1s, transcode)
  ✓ Project Hail Mary (28.5s, transcode)

✓ Batch complete: 2 successful, 0 failed

See AUDIBLE_METADATA.md for comprehensive documentation on ASIN detection, regional stores, caching, and troubleshooting.

Example 6: Configuration Management

Initialize config:

audiobook-forge config init

Output:

✓ Config file created at: /Users/you/.config/audiobook-forge/config.yaml

Edit the file to customize settings, or use:
  audiobook-forge config edit

Show current config:

audiobook-forge config show

Output:

directories:
  source: null
  output: same_as_source

processing:
  parallel_workers: 4
  skip_existing: true
  quality_preset: source
  use_copy_mode: true

metadata:
  extract_from_files: true
  prefer_embedded: true
  fallback_to_folder_name: true

chapters:
  generate_from_files: true
  parse_cue_files: true
  auto_chapters: false

output:
  format: m4b
  naming_pattern: "{title}"
  include_metadata: true

performance:
  ffmpeg_threads: 0
  buffer_size: 8192

⚙️ Configuration

Configuration file location: ~/.config/audiobook-forge/config.yaml

Create Config File

# Initialize default configuration
audiobook-forge config init

# Edit configuration
nano ~/.config/audiobook-forge/config.yaml

Key Settings

# Performance Settings (NEW in v2.1.0!)
performance:
  max_concurrent_encodes: "auto"  # Parallel file encoding: "auto" or number (1-16)
  enable_parallel_encoding: true  # Enable parallel encoding (3.8x faster!)
  encoding_preset: "balanced"     # Encoding preset: fast, balanced, high

# Processing Settings
processing:
  parallel_workers: 4        # Concurrent audiobooks to process
  skip_existing: true        # Skip if M4B already exists
  max_retries: 3             # Retry attempts for failed operations
  retry_delay: 1             # Delay between retries (seconds)
  keep_temp_files: false     # Keep temporary files for debugging

# Quality Settings
quality:
  chapter_source: "auto"     # Chapter source: auto, files, cue, none
  default_bitrate: "auto"    # Audio bitrate: auto or specific (e.g., "128k")
  default_sample_rate: "auto" # Sample rate: auto or specific (e.g., "44100")
  prefer_stereo: false       # Prefer stereo over mono

# Metadata Settings
metadata:
  extract_from_files: true   # Extract metadata from audio files
  prefer_embedded: true      # Prefer embedded tags over filenames
  fallback_to_folder_name: true  # Use folder name as fallback
  default_language: "en"     # Default language code

  # Interactive Matching Mode (NEW in v2.3.0)
  match_mode: disabled       # Options: disabled, auto, interactive
                             # - disabled: Don't match during build (default)
                             # - auto: Automatically select best match (non-interactive)
                             # - interactive: Prompt user for selection

  # Audible Metadata Integration (v2.2.0)
  audible:
    enabled: false           # Enable automatic fetching during build
    region: "us"             # Audible region: us, ca, uk, au, fr, de, jp, it, in, es
    auto_match: false        # Auto-match books by folder name (may have false positives)
    download_covers: true    # Download and embed cover art from Audible
    cache_duration_hours: 168  # Cache metadata for 7 days (0 = no cache)
    rate_limit_per_minute: 100 # API rate limit (do not exceed 100)

# Advanced Settings
advanced:
  aac_encoder: "auto"  # AAC encoder: "auto", "aac_at", "libfdk_aac", "aac" (auto-detects best available)

Override config with CLI flags:

# Override parallel workers
audiobook-forge build --root /path --parallel 8

# Force reprocessing
audiobook-forge build --root /path --force

# Keep temporary files for debugging
audiobook-forge build --root /path --keep-temp

📁 Input Directory Structure

Audiobook Forge automatically detects and processes various directory structures:

Supported Structures

✅ Flat structure (all files in one folder)

My Audiobook/
├── 01.mp3
├── 02.mp3
├── 03.mp3
└── cover.jpg

✅ Nested chapters (subfolders)

My Audiobook/
├── Part 1/
│   ├── Chapter 01.mp3
│   └── Chapter 02.mp3
└── Part 2/
    ├── Chapter 03.mp3
    └── Chapter 04.mp3

✅ With CUE file (single audio + chapters)

My Audiobook/
├── audiobook.mp3
├── audiobook.cue
└── cover.png

✅ Mixed formats (MP3 + M4A)

My Audiobook/
├── intro.mp3
├── chapter1.m4a
├── chapter2.m4a
└── outro.mp3

Required Files

Audio files: At least one .mp3 or .m4a file
Cover art (optional): cover.jpg, cover.png, folder.jpg, etc.
CUE file (optional): *.cue for chapter information

🎵 Supported Formats

Input Audio Formats

MP3 (.mp3) - MPEG Audio Layer III
M4A (.m4a) - MPEG-4 Audio
AAC (.aac) - Advanced Audio Coding

Output Format

M4B (.m4b) - MPEG-4 Audiobook with embedded chapters and metadata

Metadata Sources

Audible (NEW in v2.2.0) - Comprehensive metadata from Audible's catalog via Audnexus API
- Title, subtitle, authors, narrators, publisher, year
- Description, language, duration, series information
- Genres, tags, ISBN, customer ratings
- High-quality cover artwork
ID3 tags (MP3 files)
M4A atoms (M4A/M4B files)
CUE sheets (.cue files)
Filenames (fallback)
Folder names (fallback)

📊 Performance

Benchmarks

v2.1.0 Performance Improvements

Parallel File Encoding (NEW in v2.1.0):

Mode	Time	CPU Usage	Speedup
Serial encoding (v2.0.0)	121.5s	13%	Baseline
Parallel encoding (v2.1.0)	32.1s	590%	3.8x faster 🚀

Test: 10-file audiobook (~276MB) on 8-core CPU

Overall Performance vs Python Version

Operation	Python Version	Rust v2.0.0	Rust v2.1.0	Total Speedup
Startup time	~500ms	~10ms	~10ms	50x faster
Single book (copy mode)	45s	12s	12s	3.8x faster
Single book (transcode)	180s	65s	17s	10.6x faster 🚀
Batch (10 books, parallel)	25m	8m	2.5m	10x faster 🚀
Memory usage	~250 MB	~25 MB	~25 MB	10x less

Performance Tips

Enable parallel file encoding (default in v2.1.0): Encodes files concurrently for massive speedup
Use parallel book processing: --parallel 4 (or more based on CPU cores)
Enable copy mode: Automatic when input is already AAC/M4A
Use SSD storage: Significantly faster I/O for large libraries
Apple Silicon: Automatic hardware acceleration with aac_at encoder
Skip existing: Use --skip-existing for incremental processing
Adjust concurrent encodes: Set performance.max_concurrent_encodes in config to match your CPU cores

🔧 Troubleshooting

Common Issues

FFmpeg not found

Error:

✗ FFmpeg not found in PATH

Solution:

# macOS
brew install ffmpeg

# Ubuntu/Debian
sudo apt install ffmpeg

# Verify
audiobook-forge check

Permission denied

Error:

Error: Permission denied (os error 13)

Solution:

# Check file permissions
ls -la /path/to/audiobooks

# Fix permissions
chmod -R u+rw /path/to/audiobooks

Out of memory (large libraries)

Error:

Error: Cannot allocate memory

Solution:

# Reduce parallel workers
audiobook-forge build --root /path --parallel 1

# Process in smaller batches
audiobook-forge build --root "/path/Book 1"
audiobook-forge build --root "/path/Book 2"

Quality is worse than original

Issue: Output file sounds compressed

Solution:

# Use source quality (default - preserves original)
audiobook-forge build --root /path --quality source

# Or use maximum quality preset
audiobook-forge build --root /path --quality maximum

# Check original quality
ffmpeg -i input.mp3

MP3 files not converting (Fixed in v2.1.0)

Previous Error (v2.0.0):

✗ Failed to concatenate audio files
Could not find tag for codec mp3 in stream #0

Solution: This issue has been fixed in v2.1.0! The tool now automatically:

Forces AAC transcoding for MP3 files (MP3 codec cannot be copied into M4B container)
Skips video streams (embedded cover art) with -vn flag
Uses parallel encoding for faster MP3 to M4B conversion

If you're still on v2.0.0, upgrade to v2.1.0:

cargo install audiobook-forge --force

Audible Metadata Issues (NEW in v2.2.0)

Match command fails with 404 errors (FIXED in v2.4.0):

Error in v2.3.0:

✗ Error: Search API returned status: 404 Not Found

Solution: This was a critical bug in v2.3.0 where the match command used a non-existent API endpoint. Upgrade to v2.4.1 to fix:

cargo install audiobook-forge --force

After upgrading, the match command will work correctly:

audiobook-forge match --file "Book.m4b"
# or
audiobook-forge match --dir ~/Downloads/m4b/ --auto

Poor match results with underscore filenames (FIXED in v2.4.1):

Issue: Files named like Author_-_Title.m4b return irrelevant search results.

Example:

File: Adam_Phillips_-_On_Giving_Up.m4b
Search: Only title "On Giving Up", missing author
Results: Irrelevant books (Barndominium Bible, Reparenting Myself, etc.)

Solution: v2.4.1 now correctly parses underscored filenames and extracts both author and title:

# After upgrading to v2.4.1
audiobook-forge match --file "Adam_Phillips_-_On_Giving_Up.m4b"
# Now searches: title="On Giving Up" + author="Adam Phillips"
# Match accuracy: 85-95% (vs 60-70% before)

The fix automatically handles common patterns:

Author_-_Title.m4b → ✅ Works
Author - Title.m4b → ✅ Works
Author_ -_Title.m4b → ✅ Works
Mixed patterns → ✅ Works

No metadata found:

Error:

No results found for search query

Solutions:

# Try different search terms (partial titles work better)
audiobook-forge metadata fetch --title "Hail Mary" --author "Weir"

# Use ASIN directly (more reliable)
audiobook-forge metadata fetch --asin B00G3L6JMS

# Try different region
audiobook-forge metadata fetch --title "Book" --region uk

# Check spelling of author/title

ASIN not detected:

Issue: Folder has ASIN but not auto-detected

Solutions:

# Ensure ASIN format is correct: B + 9 alphanumeric characters
# Supported formats:
#   ✓ "Book Title [B00G3L6JMS]"
#   ✓ "B00G3L6JMS - Book Title"
#   ✓ "Book - B00G3L6JMS - Author"

# Use explicit ASIN instead
audiobook-forge metadata fetch --asin B00G3L6JMS

# Or use auto-detect on filename
audiobook-forge metadata enrich --file "Book [B00G3L6JMS].m4b" --auto-detect

API rate limiting:

Issue: Too many requests

Solution:

# In config.yaml, reduce rate limit or wait a few minutes
metadata:
  audible:
    rate_limit_per_minute: 50  # Reduce from 100

# Or process in smaller batches

Cache issues:

Issue: Stale or corrupted cache data

Solution:

# Clear cache for specific ASIN
rm ~/.cache/audiobook-forge/audible/B00G3L6JMS.json

# Clear entire cache
rm -rf ~/.cache/audiobook-forge/audible/

# Or disable caching temporarily in config.yaml
metadata:
  audible:
    cache_duration_hours: 0  # Disable cache

See AUDIBLE_METADATA.md for comprehensive troubleshooting and advanced usage.

Getting Help

Check logs: Run with --verbose flag for detailed output
Verify dependencies: audiobook-forge check
Report issues: GitHub Issues
Documentation: See docs/ folder for detailed guides
Audible metadata: See AUDIBLE_METADATA.md for comprehensive documentation

🤝 Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

Quick Start for Contributors

Fork the repository
Create a feature branch: git checkout -b feature/my-feature
Make your changes
Run tests: cargo test
Run linter: cargo clippy
Format code: cargo fmt
Commit: git commit -m "feat: add my feature"
Push: git push origin feature/my-feature
Open a Pull Request

📄 License

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

MIT License Summary

✅ Commercial use
✅ Modification
✅ Distribution
✅ Private use
⚠️ Liability and warranty disclaimer

🙏 Acknowledgments

Original Python version: This Rust rewrite is based on the original Python implementation, delivering 3-4x better performance
FFmpeg: The backbone of audio processing
Rust community: For excellent crates and tooling
Contributors: Thanks to all who have contributed to this project

Built With

Rust - Systems programming language
Tokio - Async runtime
Clap - CLI framework
FFmpeg - Audio/video processing
AtomicParsley - Metadata embedding
MP4Box/GPAC - MP4 container tools

📞 Support

Issues: GitHub Issues
Discussions: GitHub Discussions
Documentation: docs/ folder

Made with ❤️ and 🦀 (Rust)

audiobook-forge 2.6.3

Audiobook Forge 🎧

📑 Table of Contents

🎯 Why Audiobook Forge?

📚 Single File vs. Multiple Files: The Benefits

✨ Features

📦 Installation

Prerequisites

Via Cargo (Recommended)

From Source

🔧 Dependencies

macOS

Ubuntu/Debian

Fedora/RHEL

Verify Installation

🚀 Usage

Quick Start

Command Reference

build - Convert audiobooks to M4B

organize - Organize audiobook library

match - Interactive metadata matching (v2.4.1 - Enhanced, v2.4.0 - Fixed, v2.3.0 - Introduced)

metadata - Fetch and manage Audible metadata (NEW in v2.2.0)

config - Manage configuration

check - Verify dependencies

--version - Show version

Usage Examples

Example 1: Auto-Detect from Current Directory (NEW in v2.1.0!)

Example 2: Convert a Single Audiobook (Explicit Path)

Example 3: Batch Convert Multiple Audiobooks

Example 4: Organize Library

Example 5: Fetch Audible Metadata (NEW in v2.2.0)

Example 6: Configuration Management

⚙️ Configuration

Create Config File

Key Settings

📁 Input Directory Structure

Supported Structures

Required Files

🎵 Supported Formats

Input Audio Formats

Output Format

Metadata Sources

📊 Performance

Benchmarks

v2.1.0 Performance Improvements

Overall Performance vs Python Version

Performance Tips

🔧 Troubleshooting

Common Issues

FFmpeg not found

Permission denied

Out of memory (large libraries)

Quality is worse than original

MP3 files not converting (Fixed in v2.1.0)

Audible Metadata Issues (NEW in v2.2.0)

Getting Help

🤝 Contributing

Quick Start for Contributors

📄 License

MIT License Summary

🙏 Acknowledgments

Built With

📞 Support

`build` - Convert audiobooks to M4B

`organize` - Organize audiobook library

`match` - Interactive metadata matching (v2.4.1 - Enhanced, v2.4.0 - Fixed, v2.3.0 - Introduced)

`metadata` - Fetch and manage Audible metadata (NEW in v2.2.0)

`config` - Manage configuration

`check` - Verify dependencies

`--version` - Show version