Lzma - LZMA Compression Library

A .NET implementation of the LZMA (Lempel-Ziv-Markov chain-Algorithm) compression algorithm. This library provides stream-based compression and decompression capabilities with a simple, easy-to-use API.

Features

• Stream-based LZMA compression and decompression
• Compatible with .lzma file format
• Full control over compression parameters
• Support for both raw LZMA streams and containerized streams
• Configurable dictionary size, literal context bits, and other encoding properties

Installation

Add a reference to the Lzma project in your solution.

Quick Start

Basic Compression

using System.IO; using System.IO.Compression; using Lzma; // Compress data to a file using (var fileStream = File.Create("output.lzma")) using (var lzmaStream = new LzmaStream(fileStream, CompressionMode.Compress, leaveOpen: false)) { byte[] data = System.Text.Encoding.UTF8.GetBytes("Hello, LZMA!"); lzmaStream.Write(data, 0, data.Length); }

Basic Decompression

using System.IO; using System.IO.Compression; using Lzma; // Decompress data from a file using (var fileStream = File.OpenRead("output.lzma")) using (var lzmaStream = new LzmaStream(fileStream, CompressionMode.Decompress, leaveOpen: false)) { byte[] buffer = new byte[1024]; int bytesRead = lzmaStream.Read(buffer, 0, buffer.Length); string result = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead); Console.WriteLine(result); // Output: Hello, LZMA! }

API Reference

LzmaStream Class

The main class for LZMA compression/decompression. Inherits from System.IO.Stream.

Constructors

// Create a compression or decompression stream with default settings LzmaStream(Stream stream, CompressionMode mode, bool leaveOpen) // Create a compression stream with specified compression level LzmaStream(Stream stream, CompressionLevel level, bool leaveOpen) // Create a compression stream with custom encoder properties LzmaStream(Stream stream, EncoderProperties properties)

Properties

• CanRead - Returns true if the stream is in decompression mode
• CanWrite - Returns true if the stream is in compression mode
• CanSeek - Always returns false (seeking is not supported)
• Length - Gets the length of the decoded data (decompression mode only)

Methods

• Read(byte[] buffer, int offset, int count) - Reads and decodes data (decompression mode)
• Write(byte[] buffer, int offset, int count) - Encodes and writes data (compression mode)
• Flush() - Flushes the stream and completes compression
• Close() - Closes the stream

Advanced Usage

Custom Compression Settings

using Lzma; // Create custom encoder properties var encoderProperties = new EncoderProperties( workingSize: 1u << 12, // Encoding buffer size dictionarySize: 1u << 24, // 16 MB dictionary lc: 3, // Literal context bits (0-8) lp: 0, // Literal position bits (0-4) pb: 2, // Position bits (0-4) writeEndMarker: true // Write end marker on close ); using (var fileStream = File.Create("output.lzma")) using (var lzmaStream = new LzmaStream(fileStream, encoderProperties)) { // Compress with custom settings byte[] data = File.ReadAllBytes("input.txt"); lzmaStream.Write(data, 0, data.Length); }

EncoderProperties

Controls the compression behavior:

EncoderProperties properties = EncoderProperties.Default; // Adjust properties properties.DictionarySize = 1u << 23; // 8 MB dictionary properties.LC = 3; // Literal context bits properties.LP = 0; // Literal position bits properties.PB = 2; // Position bits properties.WriteEndMarker = true; // Write end marker

Property Descriptions:

• WorkingSize - Size of the encoding buffer in bytes
• DictionarySize - Size of the dictionary in bytes (larger = better compression, more memory)
• LC - Number of high bits of previous byte to use as context (0-8)
• LP - Number of low bits of dictionary position to include in literal position state (0-4)
• PB - Number of low bits of dictionary position to include in position state (0-4)
• WriteEndMarker - Whether to write an end marker when encoding is complete

Working with Raw LZMA Streams

For raw LZMA streams without container headers, use EncoderStream and DecoderStream directly:

Raw Compression

using Lzma; using (var fileStream = File.Create("output.raw")) { var encoderStream = new EncoderStream(fileStream); encoderStream.Initialize(EncoderProperties.Default); byte[] data = System.Text.Encoding.UTF8.GetBytes("Raw LZMA data"); encoderStream.Write(data, 0, data.Length); encoderStream.Close(); }

Raw Decompression

using Lzma; using (var fileStream = File.OpenRead("output.raw")) { var decoderProperties = DecoderProperties.Default; var decoderStream = new DecoderStream(fileStream); decoderStream.Initialize(decoderProperties); byte[] buffer = new byte[1024]; int bytesRead = decoderStream.Read(buffer, 0, buffer.Length); string result = System.Text.Encoding.UTF8.GetString(buffer, 0, bytesRead); }

Usage Examples

Compress a File

using System.IO; using System.IO.Compression; using Lzma; public void CompressFile(string inputPath, string outputPath) { using (var inputStream = File.OpenRead(inputPath)) using (var outputStream = File.Create(outputPath)) using (var lzmaStream = new LzmaStream(outputStream, CompressionMode.Compress, false)) { inputStream.CopyTo(lzmaStream); } }

Decompress a File

using System.IO; using System.IO.Compression; using Lzma; public void DecompressFile(string inputPath, string outputPath) { using (var inputStream = File.OpenRead(inputPath)) using (var lzmaStream = new LzmaStream(inputStream, CompressionMode.Decompress, false)) using (var outputStream = File.Create(outputPath)) { lzmaStream.CopyTo(outputStream); } }

Compress in Memory

using System.IO; using System.IO.Compression; using Lzma; public byte[] CompressData(byte[] data) { using (var memoryStream = new MemoryStream()) { using (var lzmaStream = new LzmaStream(memoryStream, CompressionMode.Compress, true)) { lzmaStream.Write(data, 0, data.Length); } return memoryStream.ToArray(); } } public byte[] DecompressData(byte[] compressedData) { using (var inputStream = new MemoryStream(compressedData)) using (var lzmaStream = new LzmaStream(inputStream, CompressionMode.Decompress, true)) using (var outputStream = new MemoryStream()) { lzmaStream.CopyTo(outputStream); return outputStream.ToArray(); } }

Compress Text

using System.IO; using System.IO.Compression; using System.Text; using Lzma; public string CompressString(string text) { byte[] data = Encoding.UTF8.GetBytes(text); using (var memoryStream = new MemoryStream()) { using (var lzmaStream = new LzmaStream(memoryStream, CompressionMode.Compress, true)) { lzmaStream.Write(data, 0, data.Length); } return Convert.ToBase64String(memoryStream.ToArray()); } } public string DecompressString(string compressedBase64) { byte[] compressedData = Convert.FromBase64String(compressedBase64); using (var inputStream = new MemoryStream(compressedData)) using (var lzmaStream = new LzmaStream(inputStream, CompressionMode.Decompress, true)) using (var outputStream = new MemoryStream()) { lzmaStream.CopyTo(outputStream); return Encoding.UTF8.GetString(outputStream.ToArray()); } }

Important Notes

• Always call Flush() or Close() on the compression stream to ensure all data is written
• The stream does not support seeking (CanSeek is always false)
• For compression, the decompressed size is written to the header automatically
• Larger dictionary sizes provide better compression but require more memory
• The default encoder properties provide a good balance between compression ratio and speed

Performance Tips

1. Dictionary Size: Use the largest dictionary size that fits in available memory
2. Working Size: Increase for better compression on large files
3. Reuse Streams: When compressing multiple small files, consider reusing stream instances
4. Buffer Size: Use appropriate buffer sizes when reading/writing data

Target Frameworks

• .NET Standard 2.0
• .NET 6.0
• .NET 10.0

License

This library is distributed under its respective license. Please refer to the source code headers for details.