procedure CompressFile(const inFile, outFile: String);
var
  zStream  : TZCompressionStream;
  inStream : TFileStream;
  outStream: TFileStream;
  size     : Cardinal;
begin
  // open the in file and get the size

  inStream := TFileStream.Create(inFile,fmOpenRead);
  size := inStream.Size;

  // create the out file and save the original (decompressed)
  // file size to make decompression easier

  outStream := TFileStream.Create(outFile,fmCreate);
  outStream.Write(size,SizeOf(Cardinal));

  // compress

  zStream := TZCompressionStream.Create(outStream);
  zStream.CopyFrom(inStream,0);

  // clean up

  zStream.Free;
  outStream.Free;
  inStream.Free;
end;

procedure DecompressFile(const inFile, outFile: String);
var
  zStream  : TZDecompressionStream;
  inStream : TFileStream;
  outStream: TFileStream;
  size     : Cardinal;
begin
  // open the in file and get the original (decompressed)
  // file size

  inStream := TFileStream.Create(inFile,fmOpenRead);
  inStream.Read(size,SizeOf(Cardinal));

  // create the out file

  outStream := TFileStream.Create(outFile,fmCreate);

  // decompress

  zStream := TZDecompressionStream.Create(inStream);
  outStream.CopyFrom(zStream,size);

  // clean up

  zStream.Free;
  outStream.Free;
  inStream.Free;
end;