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MUX is a full motion video format used in a small number of computer games. The format packages raw, unsigned, 8-bit PCM audio along with a custom video coding format.

File Format

All multi-byte numbers are little endian. The file format is laid out as follows:

 dword signature        - file signature, 0xAA07
 word  headersize       - size of the whole header, including frames table
 word  unknown1
 word  unknown2
 word  unknown3
 word  framerate        - movie playback rate, direct PIC initializer
 word  soundfrequency   - audio playback frequency
 word  audio_flags1     - unknown
 word  audio_flags2     - unknown
 word  soundbuffer_size - suggested size of the single audio buffer
 dword chunkbuffer_size - suggested size of the chunk load buffer
 word  sound_buffers    - suggested number of sound buffers
 word  width            - width of the frame
 word  height           - height of the frame

Then followed by frame offsets table. Each frame offset is 32 bits. The top 2 bits of each offset contains flags (completely ignored by original player) the rest is an absolute offset of the frame chunks. The last entry in the table is all 1s (0xFFFFFFFF) and the remainder of the table is all 0s. Note, that table contains offset to the first chunk of each frame. This chunk can be followed by other frame's chunks (ex, it's video, audio and palette parts), but they doesn't appear in offsets table.

Frames contain 1 or more chunks, each of which are formatted in a manner that is reminiscent of the Autodesk FLIC format:

 byte  0      chunk type
 byte  1      chunk subtype
 bytes 2-5    chunk size, not including this 6-byte header
 bytes 6..    chunk payload

Known chunk types appear to include:

 07    unsigned, 8-bit PCM audio
 70    palette chunk, 0x300 (768) bytes/256 RGB components, and each component is 8 bits
        (not 6 bits, like VGA palettes are normally stored)
 6F    video chunks
 05    sync chunk. usually the last chunk of the frame, 2-byte payload contains frame number
 04    eof-chunk, indicates end of the movie

Video Format

The video format is mostly similar to HNM (1) compression.

Games That Use MUX

These games are known to use MUX files for FMV: