Compression Algorithms

Purpose

This section explains the 5 compression algorithms supported by Cabriolet, helping you choose the right algorithm for your needs and understand how each works.

References

Concepts

Compression algorithms trade off between compression ratio, speed, and memory usage. Cabriolet supports multiple algorithms to match different use cases, from fast extraction to maximum compression.

Supported Algorithms

None - Uncompressed storage

None Compression Guide

  • Compression: 0% (stores uncompressed)

  • Speed: Fastest extraction

  • Memory: Minimal

  • Use Cases: Pre-compressed files, fast access, testing

LZSS - Dictionary compression

LZSS Compression Guide

  • Compression: Moderate (40-60%)

  • Speed: Fast compression and extraction

  • Memory: Low (small window)

  • Use Cases: Legacy compatibility, simple compression

MSZIP - DEFLATE-based compression

MSZIP Compression Guide

  • Compression: Good (50-70%)

  • Speed: Balanced

  • Memory: Moderate

  • Use Cases: General purpose, ZIP compatibility, default choice

LZX - High compression

LZX Compression Guide

  • Compression: Excellent (60-80%)

  • Speed: Slower compression, fast extraction

  • Memory: High (large window)

  • Use Cases: Software distribution, maximum compression, archival

Quantum - Memory-efficient compression

Quantum Compression Guide

  • Compression: Good (55-75%)

  • Speed: Moderate

  • Memory: Configurable window

  • Use Cases: Memory-constrained environments, variable compression

Algorithm comparison

Algorithm Ratio Speed Memory Best For

None

0%

★★★★★

★★★★★

Pre-compressed data

LZSS

★★☆☆☆

★★★★☆

★★★★☆

Legacy files, simple compression

MSZIP

★★★☆☆

★★★☆☆

★★★☆☆

General purpose, default

LZX

★★★★★

★★☆☆☆

★★☆☆☆

Software distribution

Quantum

★★★★☆

★★★☆☆

★★★★☆

Variable requirements

Quick selection guide

Choose None when:

  • Files are already compressed (images, videos, zip files)

  • Fast extraction is critical

  • Testing or debugging

Choose LZSS when:

  • Working with SZDD or KWAJ formats

  • Simplicity is important

  • Legacy compatibility required

Choose MSZIP when:

  • General-purpose compression needed

  • Balanced performance desired

  • Default recommendation

Choose LZX when:

  • Maximum compression ratio needed

  • Distribution package size matters

  • Extraction speed more important than compression speed

Choose Quantum when:

  • Memory constraints exist

  • Configurable compression needed

  • Moderate compression acceptable

Usage examples

Specifying compression algorithm 

# Create with MSZIP (default)
cabriolet create archive.cab files/

# Create with LZX for maximum compression
cabriolet create --compression=lzx small.cab files/

# Create uncompressed for speed
cabriolet create --compression=none fast.cab files/

Using the Ruby API 

require 'cabriolet'

# Create with specific compression
compressor = Cabriolet::CAB::Compressor.new(compression: :lzx)
compressor.add_file('large-file.dat')
compressor.write('compressed.cab')

# Detect compression of existing archive
decompressor = Cabriolet::CAB::Decompressor.new('archive.cab')
puts "Compression: #{decompressor.cabinet.folders.first.compression}"

Performance considerations

Compression time vs. ratio

Higher compression ratios require more processing time:

File: 10MB uncompressed data

None:    0.1s → 10MB    (0% compression)
LZSS:    1.2s →  6MB    (40% compression)
MSZIP:   2.5s →  4MB    (60% compression)
LZX:     8.0s →  2.5MB  (75% compression)
Quantum: 4.0s →  3MB    (70% compression)

Memory usage

Different algorithms have different memory requirements:

  • None: <1MB

  • LZSS: 8KB - 64KB window

  • MSZIP: 32KB window

  • LZX: 32KB - 2MB window (configurable)

  • Quantum: 64KB - 2MB window (configurable)

Format Compatibility

Not all formats support all compression algorithms:

Format Supported Algorithms

CAB

None, MSZIP, LZX, Quantum

CHM

LZX only

SZDD

LZSS only

KWAJ

LZSS, MSZIP

HLP

LZ77 variant (automatic)

LIT

DES + compression (automatic)

OAB

LZX only

Next steps

Bibliography

Related sections