SI Files
SI files are general purpose asset archives derived from the Resource Interchange File Format standard (best known as the basis of AVI and WAV files). They are comprised of various different structures including MxDa and MxCh.
To compensate for slow, early CD-ROM speeds, various types of data in SI files are often interleaved so they can be read as one continuous stream. For example, a chunk of music data may be followed by a chunk of animation data or a bitmapped graphic. This helps reduce the amount of seeking around the disc for assets, but needs to be taken account when extracting data from an SI file since one file stream may be separated into several chunks with chunks of other data types between them.
SI files are known to contain Microsoft WAV compatible audio and BMP file format compatible graphics.
Audio from SI files can be crudely listened to using Audacity's "Import Raw Data" feature. SI audio is always uncompressed mono PCM and is either 11025 Hz and 16-bit or 22050 Hz and 8-bit. Unfortunately due to the aforementioned chunked/interleaved nature of SI files, the audio retrieved through this method will be noticeably glitchy and will require further processing (removal of chunk headers and any non-audio chunks) to extract clean PCM data.