libbbf: Bound Book Format

Bound Book Format (.bbf) is a high-performance binary container designed specifically for digital comic books and manga. Unlike CBR/CBZ, BBF is built for DirectSotrage/mmap, easy integrity checks, and mixed-codec containerization.

Getting Started

Prerequisites

• C++17 compliant compiler (GCC/Clang/MSVC), and optionally CMake
• xxHash library

Compilation

CMake

cmake -B build
cmake --build build
sudo cmake --install build

Manual

Linux

g++ -std=c++17 bbfenc.cpp libbbf.cpp xxhash.c -o bbfmux -pthread

Windows

g++ -std=c++17 bbfenc.cpp libbbf.cpp xxhash.c -o bbfmux -municode

Alternatively, if you need python support, use libbbf-python.

Technical Details

BBF is designed as a Footer-indexed binary format. This allows for rapid append-only creation and immediate random access to any page without scanning the entire file.

MMAP Compatibility

The bbfmux reference implementation utilizes Memory Mapping (mmap/MapViewOfFile). Instead of reading file data into intermediate buffers, the tool maps the container directly into the process address space. This allows the CPU to access image data at the speed of your NVMe drive’s hardware limit.

High-Speed Parallel Verification

Integrity checks utilize Parallel XXH3. On multi-core systems, the verifier splits the asset table into chunks and validates multiple pages simultaneously. This makes BBF verification up to 10x faster than ZIP/RAR CRC checks.

4KB Alignment

Every asset in a BBF file starts on a 4096-byte boundary. This alignment is critical for modern hardware, allowing for DirectStorage transfers directly from disk to GPU memory, bypassing CPU bottlenecks entirely.

Note: DirectStorage isn’t avaliable for images yet (as far as I know), but I’ve made sure to accomodate such a thing in the future with this format.

Binary Layout

1. Header (13 bytes): Magic BBF1, versioning, and initial padding.
2. Page Data: The raw image payloads (AVIF, PNG, etc.), each padded to 4096-byte boundaries.
3. String Pool: A deduplicated pool of null-terminated strings for metadata and section titles.
4. Asset Table: A registry of physical data blobs with XXH3 hashes.
5. Page Table: The logical reading order, mapping logical pages to assets.
6. Section Table: Markers for chapters, volumes, or gallery sections.
7. Metadata Table: Key-Value pairs for archival data (Author, Scanlation team, etc.).
8. Footer (76 bytes): Table offsets and a final integrity hash.

NOTE: libbbf.h includes a flags field, as well as extra padding for each asset entry. This is so that in the future libbbf can accomodate future technical advancements in both readers and image storage. I.E. If images support DirectStorage in the future, then BBF will be able to use it.

Feature Comparison: Digital Comic & Archival Formats

[1] – PDF supports XObjects to reuse resources, but lacks native content-hash deduplication; identical images must be manually referenced.
[2] – CBZ does not support metadata natively in the ZIP spec; it relies on unofficial sidecar files like ComicInfo.xml.
[3] – While folders allow memory mapping, individual images within them are rarely sector-aligned for optimized DirectStorage throughput.
[4] – ZIP/RAR require large, complex libraries (zlib/libarchive); BBF is a “Plain Old Data” (POD) format requiring only a few lines of C++ to parse.
[5] – ZIP/RAR use CRC32, which is aging, collision-prone, and significantly slower to verify than XXH3 for large archival collections. See [8].
[6] – Because the index is at the end (Footer), web-based streaming requires a “Range Request” to the end of the file before reading pages.
[7] – PDF supports “Linearization” (Fast Web View), allowing the header and first pages to be read before the rest of the file is downloaded.
[8] – As Reddit properly corrected me, ZIP/RAR does have random access.
[9] – While I think CRC32 is a legacy hash format, ZIP/RAR does have verification ability, though somewhat outdated. See [5].

Graphical Comparison (BBF vs. CBZ)

Features

Content Deduplication

BBF uses XXH3_64 hashing to identify identical pages. If a book contains duplicate pages, the data is stored exactly once on disk while being referenced multiple times in the Page Table.

Archival Integrity

BBF stores a 64-bit hash for every individual asset. The bbfmux --verify command can pinpoint exactly which page has been damaged, rather than simply failing to open the entire archive.

Mixed-Codec Support

Preserve covers in Lossless PNG while encoding internal story pages in AVIF to save 70% space. BBF explicitly flags the codec for every asset, allowing readers to initialize the correct decoder instantly without “guessing” the file type.

CLI Usage: bbfmux

The included bbfmux tool is a reference implementation for creating and managing BBF files.

CLI Features

The bbfmux utility provides a powerful interface for managing Bound Book files:

• Flexible Ingestion: Create books by passing individual files, entire directories, or a mix of both.
• Logical Structuring: Add named Sections (Chapters, Volumes, Extras, Galleries) to define the internal hierarchy of the book.
• Custom Metadata: Embed arbitrary Key:Value pairs into the global string pool for archival indexing.
• Content-Aware Extraction: Extract the entire book or target specific sections by name.

Usage Examples

Create a new BBF

You can mix individual images and folders. bbfmux sorts inputs alphabetically, deduplicates identical assets, and aligns data to 4096-byte boundaries. See Advanced CLI Usage for how to specify your own custom page orders.

# Basic creation with metadata
bbfmux cover.png ./chapter1/ endcard.png 
  --meta=Title:"Akira" 
  --meta=Author:"Katsuhiro Otomo" 
  --meta=Tags:"[Action, Sci-Fi, Cyberpunk]" 
  akira.bbf

Hierarchical Sections (Volumes & Chapters)

BBF supports nesting sections. By defining a Parent relationship, you can group chapters into volumes. This allows readers to display a nested Table of Contents and enables bulk-extraction of entire volumes.

Syntax: --section="Name":Page[:ParentName]

# Create a book with nested chapters
bbfmux ./manga_folder/ 
  --section="Volume 1":1 
  --section="Chapter 1":1:"Volume 1" 
  --section="Chapter 2":20:"Volume 1" 
  --section="Volume 2":180 
  --section="Chapter 3":180:"Volume 2" 
  manga.bbf

Verify Integrity

Scan the archive for bit-rot or data corruption. BBF uses XXH3_64 hashes to verify every individual image payload.

bbfmux input.bbf --verify

Extract Data

Extract the entire book, a specific volume, or a single chapter. When extracting a parent section (like a Volume), bbfmux automatically includes all child chapters.

Extract a specific section:

bbfmux input.bbf --extract --section="Volume 1" --outdir="./Volume1"

Extract the entire book:

bbfmux input.bbf --extract --outdir="./unpacked_book"

View Metadata & Structure

View the version, page count, deduplication stats, hierarchical sections, and all embedded metadata.

bbfmux input_book.bbf --info

Advanced CLI Features

bbfmux also supports more advanced options, allowing full-control over your .bbf files.

Custom Page Ordering (--order)

You can precisely control the reading order using a text file or inline arguments.

• Positive Integers: Fixed 1-based index (e.g., cover.png:1).
• Negative Integers: Fixed position from the end (e.g., credits.png:-1 is always the last page).
• Unspecified: Sorted alphabetically between the fixed pages.

# Using an order file
bbfmux ./images/ --order=pages.txt out.bbf

# pages.txt example:
cover.png:1
page1.png:2
page2.png:3
credits.png:-1

Batch Section Import (--sections)

Sections define Chapters or Volumes. You can target a page by its index or filename.

# Target by filename
bbfmux ./folder/ --section="Chapter 1":"001.png" out.bbf

# Using a sections file
bbfmux ./folder/ --sections=sectionexample.txt out.bbf

# sectionexample.txt example (Name:Target[:Parent]):
"Volume 1":"001.png"
"Chapter 1":"001.png":"Volume 1"
"Chapter 2":"050.png":"Volume 1"

Targeted Verification

BBF allows for verification of data to detect bit-rot.

# Verify everything (All assets and Directory structure)
bbfmux input.bbf --verify

# Verify only the directory hash (Instant)
bbfmux input.bbf --verify -1

# Verify a specific asset by index
bbfmux input.bbf --verify 42

Range-Key Extraction

The --rangekey option allows you to extract a range of sections. The extractor starts at the specified --section and stops when it finds a section whose title matches the rangekey.

# Extract Chapter 2 up until it hits Chapter 4
bbfmux manga.bbf --extract --section="Chapter 2" --rangekey="Chapter 4" --outdir="./Ch2_to_Ch4"

# Extract Volume 2 until it encounters the string "Chapter 60"
bbfmux manga.bbf --extract --section="Volume 2" --rangekey="Chapter 60" --outdir="./Volume_2_to_Chapter_60"

License

Distributed under the MIT License. See LICENSE for more information.