OMNIRIFF.txt

Lego Island JUKEBOX.SI format

RIFF based

"RIFF"      RIFF magic
4 bytes     RIFF size
"OMNI"      RIFF OMNI data

Most blocks are just a 4 byte type and a 4 byte size, except LIST blocks also
contain a subtype following the size.  Sizes are the entire size of the contents
of the block.  LIST blocks include the subtype as part of the size.

Node blocks which contain additional blocks:
LIST
    Subtypes:
    MxSt - Set of objects?
    MxDa - Data within a set of chunks?
MxSt - Set of chunks?

Leaf blocks which contain data:
MxHd - Some kind of header
MxOf - Some kind of list of offsets of interest in to the file?
MxOb - Description of a set of chunks? (object?)
    1 byte      type: 4 for WAVE audio
                      7 for FLIC/Smacker video
                      3 for muxed streams/multiple objects
                      10 for " STL" bitmap
    6 bytes     padding?
    n bytes     null terminated string name of object
    4 bytes     track number?
    4 bytes     unknown, always 34 or 36?
    4 bytes     always 0
    4 bytes     unknown, 0 if it's a video main MxOb
    4 bytes     some kind of multiple related to previous value?
    4 bytes     always 0
    2 bytes     unknown if frame, otherwise 0
    4 bytes     unknown if frame, otherwise 0
    4 bytes     always 0
    4 bytes     unknown if frame, otherwise 0
    4 bytes     always 0
    4 bytes     unknown if frame, otherwise 0
    20 bytes    always 0
    4 bytes     unknown, always 0x3FF0?
    12 bytes    always 0
    4 bytes     unknown, always 0x4FF0?
    6 bytes     always 0
    2 bytes     length of name of something, skip this many bytes
    
    The first MxOb in a muxed/multiple object track ends here ...

    n bytes     null terminated file name of object
    8 bytes     always 0
    4 bytes     always 1?
    4 bytes     format?  " WAV", " FLC", " SMK"
    4 bytes     always 1?
    4 bytes     always 0?
    4 bytes     unknown, usually 79 but for one track it's 30

    ... and continues here.

    12 bytes    a LIST MxCh header
    4 bytes     number of additional chunks
    n bytes     MxOb chunks follow

MxCh - Chunk of data
    2 bytes     usually 0, 16 if partial, last chunk is always 2
    4 bytes     the track number
    4 bytes     maybe a timestamp?
    4 bytes     chunk size but first partial chunk indicates the full size
                including additional partial chunks
    n bytes     data

    First chunks contain additional fields or header and no data:

    audio chunk:
        WAVE fmt header
        2 bytes     data type/encoding
        2 bytes     channels
        4 bytes     sample rate
        4 bytes     bytes per second
        2 bytes     bytes per sample*channels
        2 bytes     bits per sample

        4 bytes     total data size?
        4 bytes     unknown, always 44, RIFF header size?

    bitmap chunks (" STL" format):
        4 bytes     header size, including this value (start of palette?)
        4 bytes     width
        4 bytes     height
        2 bytes     always 1
        2 bytes     always 8
        4 bytes     always 0
        4 bytes     image data size
        1 byte      always 18 or 19
        1 byte      always 11
        2 bytes     always 0
        1 byte      always the same as byte 24
        1 byte      always the same as byte 25
        10 bytes    always 0
        1024 bytes  palette data, 4 bytes per entry for 256 entries

    following frame chunks for " FLC" type contain these fields:
        4 bytes     always 1
        8 bytes     always 0
        4 bytes     always the video width
        4 bytes     always the video height

    audio chunk data contains PCM audio
    video chunk data contains a FLC chunk

pad  - Padding