HINT, following a tradition of Free Software, is the recursive acronym for: HINT Is Not TEX
The HINT file format is an alternative to the DVI or PDF format that was designed specifically for reading technical documents on mobile devices. Mobile devices are available in a large variety of sizes but are typically not large enough to display documents formated for letter-size paper. To compensate for the limitations of a small screen, users are used to alternate between landscape (few long lines) and portrait (more shor lines) mode. The HINT format supports variable and varying screen sizes leveraging the ability of TEX to format a document for (almost) arbitrary values of \hsize and \vsize.
HINT consists of four parts:
The book has two main objectives:
To explain the syntax, the semantics, the mathematics, the software, and the purpose that is inherent in an MPEG audio bit stream, and to provide a highly efficient, general purpose implementation of a decoder, called mp32pcm, that can transform such a bit stream into an ordinary stream of PCM data.
More deatils and code can be found on the Understanding MP3 Page.