Shockwave .DCR file format

These are some WIP notes on the Shockwave .DCR file format.

Format

• 0000-0003: RIFX (little) or XFIR (big)
• 0004-0007: Size of file minus 8, always little-endian (? was LE on a BE file (Hannah and the Ice Caves))
• 0008-000b: MDGF (? for BE -- assuming this is FGDM for LE?)
• 000c-000f: revF (Fver for LE?)
• 0010-001f: Binary data, followed by a human-readable version string (for HatIC: 0f8a 0101 8e3a 0938 2e35 2e31 2331 3034 .....:.8.5.1#104)
• 0020-0023: rdcF (Fcdr for LE?)

Fcdr is then followed by a variable-length integer. This appears to mark the compressed size of the following data. On HatIC, this is 0x813a, which becomes 0xba (186 decimal) according to the following algorithm.

public int ReadVarInt()
{
    int value = 0;
    byte b;
    do
    {
        b = ReadByte();
        value = (value << 7) + (b & 0x7F);
    }
    while (b >> 7 != 0);
    return value;
}

The tool offzip decompresses this to 257 bytes of data.

00000000: 0300 04e9 99ac 7000 360b 0000 0800 0737  ......p.6......7
00000010: 7a34 2e98 99ac 5d00 500d 0000 0800 0737  z4....].P......7
00000020: 7a34 89a8 0472 d0af cf11 a222 00a0 2453  z4...r....."..$S
00000030: 444c 4d61 6372 6f6d 6564 6961 207a 6970  DLMacromedia zip
00000040: 6c69 6220 636f 6d70 7265 7373 696f 6e2c  lib compression,
00000050: 2063 6f6e 7461 6374 204d 6163 726f 6d65   contact Macrome
00000060: 6469 612c 2049 6e63 2e2c 2053 616e 2046  dia, Inc., San F
00000070: 7261 6e63 6973 636f 2c20 4341 004d 6163  rancisco, CA.Mac
00000080: 726f 6d65 6469 6120 6e75 6c6c 2043 6f6d  romedia null Com
00000090: 7072 6573 736f 7200 5357 4120 4465 636f  pressor.SWA Deco
000000a0: 6d70 7265 7373 6f72 2058 7472 6120 6672  mpressor Xtra fr
000000b0: 6f6d 204d 6163 726f 6d65 6469 612c 2049  om Macromedia, I
000000c0: 6e63 2e20 2028 6874 7470 3a2f 2f77 7777  nc.  (http://www
000000d0: 2e6d 6163 726f 6d65 6469 612e 636f 6d2c  .macromedia.com,
000000e0: 2063 6f6e 7461 6374 2073 7570 706f 7274   contact support
000000f0: 406d 6163 726f 6d65 6469 612e 636f 6d29  @macromedia.com)
00000100: 00

• 00e0-00e3: PMBA (ABMP for LE?)
• 00e4-00e8: Unsure, is a842 00de 13

offzip then detects 5183 bytes of compressed data (12051 uncompressed) starting at 00e9. Info.