LZMA SDK Compress Decompress

7z is one of the best if not the best file compression available. Best of all, it is open source. The engine behind it is the LZMA compression method. I was integrating the sdk (https://www.7-zip.org/sdk.html) in my project, but however, can't get a quick start on the compress decompress process. After searching the internet, I figured out on a surface level how it all works. Partially thanks to the question in https://stackoverflow.com/questions/7646328/how-to-use-the-7z-sdk-to-compress-and-decompress-a-file. So, below, I write down my basic understanding.

Compress

Basically, the compressed file will contain 3 things with the first 2 are metadata:

1. The first 5 bytes are compression properties
2. The next 8 bytes are file size before compression
3. The compressed bytes

var encoder = New Encoder();
encoder.WriteCoderProperties(outStream); // Write properties
encoder.Write(BitConverter.GetBytes(inputFileSize), 0, 8); // Write uncompressed file size
encoder.Code(inStream, outSteam, inStream.Length, -1, null); // Actual compress

Decompress

To decompress the file, the metadata needs to be provided to the decoder. My code initially threw an error because there is no metadata.

var properties = new byte[5];
inStream.Read(properties, 0, 5); // Read properties

var fileSizeBytes = new byte[8];
inStream.Read(fileSizeBytes, 0, 8); // Read uncompressed file size
var fileSize = BitConverter.ToInt64(fileSizeBytes, 0);

var decoder = New Decoder();
decoder.SetDecoderProperties(properties); // Provide the properties to decoder
decoder.Code(inStream, outStream, inStream.Length, fileSize, null); // Actual decompress