Libgta is a portable library that implements the Generic Tagged Array (GTA) file
format. This file format has the following features:
- GTAs can store any kind of data in multidimensional arrays
- GTAs can optionally use simple tags to store rich metadata
- GTAs are streamable, which allows direct reading from and writing to pipes,
  network sockets, and other non-seekable media
- GTAs can use ZLIB, BZIP2, or XZ compression, allowing a tradeoff between
  compression/decompression speed and compression ratio
- Uncompressed GTA files allow easy out-of-core data access for very large
  arrays

See http://gta.nongnu.org/ for more information.