LBR Format

The LBR Format is used by Vinyl Goddess From Mars to store most of the game data.

File format

Signature

There is no known signature for this format. One method to identify files is to read in the file entries and ensure all the offsets are within range (and perhaps increasing in value.) It is somewhat unlikely that this method would incorrectly identify a file.

Header

The header begins at the start of the file (offset 0.)

File entry

After the header, the following structure is repeated once for each file.

Each file's data starts at the offset indicated. File sizes must be calculated by comparing adjacent offsets, or in the case of the last file, comparing its offset to the total size of the LBR.

Filename hash

Rather than storing filenames, LBR files store a hash calculated from the original filename. If you have a filename it is very easy to calculate the hash, but because hashes are one-way functions, if all you have is a hash it is impossible to calculate the filename (this is because each hash matches at least 56 billion different filenames. Malvineous wrote a tool to list all possible filenames for a hash matching a given prefix and suffix, but the many thousands of names produced makes this a very tedious and error-prone way of discovering filenames.)

Some example code to calculate the hashes follows.

int calcHash(const std::string& data)
{
  int hash = 0;
  for (std::string::const_iterator i = data.begin(); i != data.end(); i++) {
    hash ^= *i << 8;
    for (int j = 0; j < 8; j++) {
      hash <<= 1;
      if (hash & 0x10000) hash ^= 0x1021;
    }
  }
  return hash & 0xffff;
}

Vgfmext also contains BASIC code to calculate hashes, using a slight variation.

Tools

The following tools are able to work with files in this format.

Credits

This file format was reverse engineered by Frenkel Smeijers with the hash algorithm refined by Malvineous. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)