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  2. Flic Files (.FLI) Format description:
  4.      The details of a FLI file are moderately complex, but the
  5. idea behind it is simple: don't bother storing the parts of a
  6. frame that are the same as the last frame.  Not only does this
  7. save space, but it's very quick.  It's faster to leave a pixel
  8. alone than to set it.
  10.      A FLI file has a 128-byte header followed by a sequence of
  11. frames. The first frame is compressed using a bytewise run-length
  12. compression scheme.  Subsequent frames are stored as the
  13. difference from the previous frame.  (Occasionally the first
  14. frame and/or subsequent frames are uncompressed.)  There is one
  15. extra frame at the end of a FLI which contains the difference
  16. between the last frame and the first frame.
  18.      The FLI header:
  20.      byte size name      meaning
  21.      offset
  23.      0    4    size      Length of file, for programs that want
  24.                          to read the FLI all at once if possible.
  25.      4    2    magic     Set to hex AF11.  Please use another
  26.                          value here if you change format (even to
  27.                          a different resolution) so Autodesk
  28.                          Animator won't crash trying to read it.
  29.      6    2    frames    Number of frames in FLI.  FLI files have
  30.                          a maxium length of 4000 frames.
  31.      8    2    width     Screen width (320).
  32.      10   2    height    Screen height (200).
  33.      12   2    depth     Depth of a pixel (8).
  34.      14   4    flags     Must be 0.
  35.      18   2    speed     Number of video ticks between frames.
  36.      20   4    next      Set to 0.
  37.      24   4    frit      Set to 0.
  38.      28   100  expand    All zeroes -- for future enhancement.
  40.      Next are the frames, each of which has a header:
  42.      byte size name      meaning
  43.      offset
  44.      0    4    size      Bytes in this frame.  Autodesk Animator
  45.                          demands that this be less than 64K.
  46.      4    2    magic     Always hexadecimal F1FA
  47.      6    2    chunks    Number of 'chunks' in frame.
  48.      8    8    expand    Space for future enhancements.  All
  49.                          zeros.
  51.      After the frame header come the chunks that make up the
  52. frame.  First comes a color chunk if the color map has changed
  53. from the last frame.  Then comes a pixel chunk if the pixels have
  54. changed.  If the frame is absolutely identical to the last frame
  55. there will be no chunks at all.
  57.      A chunk itself has a header, followed by the data.  The
  58. chunk header is:
  60.      byte size name meaning
  61.      offset
  62.      0    4    size Bytes in this chunk.
  63.      4    2    type Type of chunk (see below).
  65.      There are currently five types of chunks you'll see in a FLI
  66. file.
  68.      number    name      meaning
  69.      11        FLI_COLOR Compressed color map
  70.      12        FLI_LC    Line compressed -- the most common type
  71.                          of compression for any but the first
  72.                          frame.  Describes the pixel difference
  73.                          from the previous frame.
  74.      13        FLI_BLACK Set whole screen to color 0 (only occurs
  75.                          on the first frame).
  76.      15        FLI_BRUN  Bytewise run-length compression -- first
  77.                          frame only
  78.      16        FLI_COPY  Indicates uncompressed 64000 bytes soon
  79.                          to follow.  For those times when
  80.                          compression just doesn't work!
  82.      The compression schemes are all byte-oriented.  If the
  83. compressed data ends up being an odd length a single pad byte is
  84. inserted so that the FLI_COPY's always start at an even address
  85. for faster DMA.
  87. FLI_COLOR Chunks
  88.      The first word is the number of packets in this chunk. This
  89. is followed directly by the packets.  The first byte of a packet
  90. says how many colors to skip.  The next byte says how many colors
  91. to change.  If this byte is zero it is interpreted to mean 256.
  92. Next follows 3 bytes for each color to change (one each for red,
  93. green and blue).
  95. FLI_LC Chunks
  96.      This is the most common, and alas, most complex chunk.   The
  97. first word (16 bits) is the number of lines starting from the top
  98. of the screen that are the same as the previous frame. (For
  99. example, if there is motion only on the bottom line of screen
  100. you'd have a 199 here.)  The next word is the number of lines
  101. that do change.  Next there is the data for the changing lines
  102. themselves.  Each line is compressed individually; among other
  103. things this makes it much easier to play back the FLI at a
  104. reduced size.
  106.      The first byte of a compressed line is the number of packets
  107. in this line.  If the line is unchanged from the last frame this
  108. is zero.  The format of an individual packet is:
  110. skip_count
  111. size_count
  112. data
  114.      The skip count is a single byte.  If more than 255 pixels
  115. are to be skipped it must be broken into 2 packets. The size
  116. count is also a byte.  If it is positive, that many bytes of data
  117. follow and are to be copied to the screen.  If it's negative a
  118. single byte follows, and is repeated -size_count times.
  120.      In the worst case a FLI_LC frame can be about 70K.  If it
  121. comes out to be 60000 bytes or more Autodesk Animator decides
  122. compression isn't worthwhile and saves the frame as FLI_COPY.
  124. FLI_BLACK Chunks
  125.      These are very simple.  There is no data associated with
  126. them at all. In fact they are only generated for the first frame
  127. in Autodesk Animator after the user selects NEW under the FLIC
  128. menu.
  130. FLI_BRUN Chunks
  131.      These are much like FLI_LC chunks without the skips.  They
  132. start immediately with the data for the first line, and go line-
  133. by-line from there.  The first byte contains the number of
  134. packets in that line.  The format for a packet is:
  136. size_count
  137. data
  139.      If size_count is positive the data consists of a single byte
  140. which is repeated size_count times. If size_count is negative
  141. there are -size_count bytes of data which are copied to the
  142. screen. In Autodesk Animator if the "compressed" data shows signs
  143. of exceeding 60000 bytes the frame is stored as FLI_COPY instead.
  145. FLI_COPY Chunks
  146.      These are 64000 bytes of data for direct reading onto the
  147. screen.
  149. -----------------------------------------------------------------------
  150. And here's the PRO extensions:
  151. -----------------------------------------------------------------------
  153. This is supplemental info on the AutoDesk Animator FLI and FLC formats.
  155. The following is an attempt at describing the newer chunks and frames
  156. that are not described in the Turbo C FLI library documentation.
  158.   Chunk type       Chunk ID
  159.   ----------       -----------
  160.   FLI_DELTA        7 (decimal)
  162.   First WORD (16 bits) is the number of compressed lines to follow.  Next
  163.   is the data for the changing lines themselves, always starting with the
  164.   first line.   Each line is compressed individually.
  166.   The first WORD (16 bits) of a compressed line is the number of packets in
  167.   the line.  If the number of packets is a negative skip -packets lines.
  168.   If the number of packets is positive, decode the packets.  The format of
  169.   an individual packet is:
  171.   skip_count
  172.   size_count
  173.   data
  175.   The skip count is a single byte.  If more than 255 pixels are to be
  176.   skipped, it must be broken into 2 packets.  The size_count is also a byte.
  177.   If it is positive, that many WORDS of data follow and are to be copied to
  178.   the screen.  If it is negative, a single WORDS value follows, and is to be
  179.   repeated -size_count times.
  181.   Chunk type       Chunk ID
  182.   ----------       -----------
  183.   FLI_256_COLOR    4 (decimal)
  185.   The first WORD is the number of packets in this chunk.  This is followed
  186.   directly by the packets.  The first byte of a packet is how many colors
  187.   to skip.  The next byte is how many colors to change.  If this number is
  188.   0, (zero), it means 256.  Next follow 3 bytes for each color to change.
  189.   (One each for red, green and blue).
  191.   The only difference between a FLI_256_COLOR chunk (type 4 decimal) and a
  192.   FLI_COLOR chunk (type 11 decimal) is that the values in the type 4 chunk
  193.   range from 0 to 255, and the values in a type 11 chunk range from 0 to 63.
  195.   NOTE:  WORD  refer to a 16 bit int in INTEL (Little Endian) format.
  196.          WORDS refer to two-bytes (16 bits) of consecutive data. (Big Endian)
  198.   .FLC special frames and chunks
  200.   FLC's may contain all the above chunks plus one other:
  202.   Chunk type       Chunk ID
  203.   ----------       -----------
  204.   FLI_MINI         18 (decimal) 12 (Hex)
  206.   From what I understand,  this is a miniture 64 x 32 version of the first
  207.   frame in FLI_BRUN format, used as an button for selecting flc's from
  208.   within Animator Pro.  Simply do nothing with this chunk.
  210.   FLC New Frame
  212.   FLC's also contains a frame with the magic bytes set to hex 00A1.  This
  213.   is the first frame in the .flc file.  Actually it isn't a frame at all
  214.   but to have several chunks within it that specify file location info
  215.   specific to Animator Pro.  IE:  filepath, font to use, and .COL file info.
  216.   This FRAME may be skipped while loading.  That's right!  Ignore it!  The
  217.   frame header is the same length as all other frames.  So you may read the
  218.   frame header, then skip past the rest of the frame.
  221.   NOTE:  When reading the FLI header on the newer FLI and FLC files, the
  222.   FLI signature bytes are AF12 instead of AF11 used in the older FLI files.
  223.   Also, you cannot ignore the screen width and height they may not be
  224.   320 x 200.
  226.   Allowable screen sizes include:
  228.   320 x 200, 640 x 480, 800 x 600, 1280 x 1024
  231.   NOTE:  the delay value between frames appears to be in 1000th's of a
  232.   second instead of 70th's.
  234. If you have any questions or more info on the FLI or FLC formats,
  235. please let me know.
  237. Mike Haaland
  238. (corrected by P. Oliver 30 May 1997 using information supplied by Reeves Hall)
  240. CompuServe : 72300,1433
  241. Delphi     : MikeHaaland
  242. Internet   :
  243. Usenet     : ...!!mike