The file input support three file formats:

    Framed format is used for file recording. It is the default format. The
    padding can be removed from data. Format:
        uint32_t nbFrames
        for each frame
          uint16_t frameSize
          uint8_t data[frameSize]

    Streamed format is used for streamed applications. As the total number of
    frames is unknown before end of transmission, the corresponding field is
    removed. The padding can be removed from data. Format:
        for each frame
          uint16_t frameSize
          uint8_t data[frameSize]

    Raw format is a bit-by-bit (but byte aligned on sync) recording of a G.703
    data stream. The padding is always present. Format:
        for each frame
          uint8_t data[6144]

    Please note that our raw format can also be referred to as ETI(NI, G.703) or ETI(NI).


All numbers are little-endian.
This description has been taken from the CRC mmbTools forum.