The DCM File Format

Also known as: WUFF


Original Documentation

--------M-DCM-------------------------------
The DCM module format was designed by Winfried Welti, and is based on a
RIFF / IFF style format called WUFF - Welti's Universal File header Format.

The header for WUFF files is built much like the RIFF header :

OFFSET              Count TYPE   Description
0000h                   4 char   ID="WUFF"
0004h                   4 char   Subformat ID, see below
0008h                   1 dword  File length including the WUFF header
000Ch                   1 word   File format version as BCD.
								 Bits 15-12 are flags :
									12 - Archive file. If set, the data after the
										 header contains only WUFF style files.
								 13-15 - reserved.
000Eh                   1 word   Length of subheader following this header.

The DCM format has a header ID of "DCMw" and a version word of 0100h. It extends
the header with the following values:

0010h                   1 word  Song flags, bitmapped
								 0 - Samples present
								 1 - Songdata present
								 2 - Infotext present
							  3-15 - reserved
0012h                   1 word  Number of instruments

After the header, there follow the included (WUFF) files; Allowed fileformats
for include are : MDCw (Patterns), EDIw (Instrument), TXTw (Text); see below.

The MDC format is a module format which uses compiled pattern data. It has the
subformat ID "MDCw", the current version is 1.01, it extends the header with
the following fields :

OFFSET              Count TYPE   Description
0010h                   1 word   Flags for the song (see table 0011)
0012h                   1 word   Internal frequency for replay
0014h                   1 dword  Length of packed data channels
0028h                   1 byte   Number of used channels
  24 : Chnls   : Byte      Used Channels (0..chnls-1)

(Table 0011)
MDC song flags
   0 - Stereo enable
   1 - Free Frequency (can replay freq change in song ?)
 2-3 - Offset size  :
		00 - Byte (mod offsets, multiply by 256)
		01 - Word  (16 bit offsets)
		10 - DWord (32 bit offsets)
		11 - reserved
 4-5 - Panning range
		00 - GUS panning (4 bit, byte value)
		01 - 8 Bit panning
		10 - reserved
		11 - reserved
 6-7 - Instrument number range
		00 - Byte
		01 - Word
		10 - reserved
		11 - reserved
   8 - S3M compatibility bit (all ranges are like s3m : mod offsets,
								  GUS panning, Ins Num Range : Byte)
   9 - Tuning control
		 0 - Use Period values (word) (s3m)
		 1 - Use Frequency values (Dword)
10-15- reserved

After the header, there comes the packed data for the module. This format
consists of one control byte and depending on the value some other data
bytes.

Values of control byte :
		0 - Next Frame
		1 - End of File
		2 - Order Num. follows [byte]
		3 - Loop to Ord Num (1 byte follows)
		4 - Frames to wait follows [byte]
		5 - New Replay freq follows [byte]
	6..31 - reserved

If the byte is greater than 31 then it has the following bitmapped format :

	  0-4 - Channel Nr.
		5 - Key Byte follows
		6 - Period Value follows [word]
		7 - Volume Value follows [byte]

Key byte format, bitmapped :

		0 - Start Sample
		1 - Stop Sample
		2 - Instr Nr follows [byte/word/??]
		3 - Offset follows [byte/word/??]
		4 - Pan pos follows [byte/??]
	  5-7 - reserved

The EDI format has an ID value of "EDIw" and a version of 0100h, and it extends
the header with the following information :

OFFSET              Count TYPE   Description
0010h                   1 word   Sample flags, bitmapped
								 0-1 - Loop type
									   00 - none
									   01 - forward loop
									   10 - bidirectional loop
									   11 - reserved
								   2 - 32 bit values for sample length etc., see below
								   3 - Sample is 16 bit
								   4 - Frequency is 32 bit.
								5-15 - reserved
0012h                   1 word   C2 frequency of sample
0014h                   1 dword  Loop start, this may be a word, depending on
								 the sample flags.
0018h                   1 dword  Loop end, see loop start
001Ch                   1 dword  Sample length

The song text is plain ASCII.
EXTENSION:DCM
OCCURENCES:PC
SEE ALSO:S3M

This information is from Corion.net and is used with permission.

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