Dse smdl

General Information

The SMDL format is a container for sequenced music. Its very close to the MIDI format, similarly to the SSEQ format normally used in most NDS games.

File Structure

Overview

Offset	Length	Name	Description
0x0	64	SMDLHeader	The container's header.
0x40	64	Song Chunk	Information on the entire sequence.
After Song Chunk	Varies	Trk Chunk	The first Track of the sequence. Its role is to set the tempo.
..Additional tracks here..
After all Track Chunks	16	End of Content Chunk	This empty chunk marks the end of the SMDL container.

SMDL Header

---

Total length 64 bytes

Offset	Length	Type	Name	Description
0x00	4	char[4]	magicn	The 4 characters "smdl" {0x73,0x6D,0x64,0x6C}
0x04	4	-	unk7	4 bytes of zeroes.
0x08	4	uint32	flen	File length in bytes.
0x0C	2	uint16	version?	Version number? ( 0x1504 )
0x0E	1	uint8	unk1	Unknown.
0x0F	1	uint8	unk2	Unknown.
0x10	4	-	unk3	4 bytes of zeroes.
0x14	4	-	unk4	4 bytes of zeroes.
0x18	2	uint16	year	Year the file was last modified.
0x1A	1	uint8	month	Month the file was last modified.
0x1B	1	uint8	day	Day the file was last modified.
0x1C	1	uint8	hour	Hour the file was last modified.
0x1D	1	uint8	minute	Minute the file was last modified.
0x1E	1	uint8	second	Second the file was last modified.
0x1F	1	uint8	centisecond?	Could possibly be the centisecond that the file was last modified.
0x20	16	char[16]	fname	Filename, ASCII null terminated string. Any extra space after the 0 on the total 16 bytes, is padded with 0xAA.
0x30	4	uint32	unk5	Unknown, usually 0x1.
0x34	4	uint32	unk6	Unknown, usually 0x1.
0x38	4	uint32	unk8	Unknown, usually 0xFFFFFFFF.
0x3C	4	uint32	unk9	Unknown, usually 0xFFFFFFFF.

Song Chunk

---

The song chunk is made of a single header.

Song Chunk Header ( Total length 64 bytes )

Offset	Length	Type	Name	Description
0x00	4	char[4]	label	Song chunk label "song" {0x73,0x6F,0x6E,0x67}
0x04	4	uint32	unk1	Unknown. Usually 0x1.
0x08	4	uint32	unk2	Unknown. Usually 0xFF10.
0x0C	4	uint32	unk3	Unknown. Usually 0xFFFFFFB0.
0x10	2	uint16	unk4	Unknown. Usually 0x1.
0x12	2	uint16	tpqn	Ticks Per Quarter Note? Usually 0x30 or 48 ticks per quarter note. (Works like MIDI clock ticks it seems.) Or possibly just the tick rate..
0x14	2	uint16	unk5	Unknown. Usually 0xFF01
0x16	1	uint8	nbtrks	Number of track(trk) chunks
0x17	1	uint8	nbchans	Number of channels. (Unsure how channels works with DSE)
0x18	4	uint32	unk6	Unknown. Usually 0x0F000000
0x1C	4	uint32	unk7	Unknown. Usually 0xFFFFFFFF
0x20	4	uint32	unk8	Unknown. Usually 0x40000000
0x24	4	uint32	unk9	Unknown. Usually 0x00404000
0x28	2	uint16	unk10	Unknown. Usually 0x0200
0x2A	2	uint16	unk11	Unknown. Usually 0x0800
0x2C	4	uint21	unk12	Unknown. Usually 0xFFFFFF00
0x30	16	-	unkpad	Unknown sequence of 16, 0xFF bytes. Possibly padding?

Trk Chunk

---

Track chunks contain the events for each individual tracks of the music sequence. They work much like MIDI tracks.

Header

Offset	Length	Type	Name	Description
0x00	4	char[4]	label	Track chunk label "trk\0x20" {0x74,0x72,0x6B,0x20}
0x04	4	uint32	param1	Unknown. Usually 0x01000000.
0x08	4	uint32	param2	Unknown. Usually 0x0000FF04.
0x0C	4	uint32	chunklen	Length of the trk chunk. Starting after this field, to the first 0x98 event encountered in the track. The length is in bytes.

The content begins immediately after the header!

Preamble

Each tracks has a short preamble after the header, and before the actual events. That preamble indicates the channel and the track id assigned to the track.

Offset	Length	Type	Name	Description
0x00	1	uint8	trkid	The track ID of the track. A number between 0 and 0x11.
0x01	1	uint8	chanid	The channel ID of the track. A number between 0 and 0x0F?.
0x02	1	uint8	unk1	Unknown. Often 0.
0x03	1	uint8	unk2	Unknown. Often 0.

Events

All tracks must have a 0x98 event at their end. And the size of a track is counted up to that event, ignoring the padding bytes. Events themselves are not aligned on 4 bytes.

Offset	Length	Type	Name	Description
After Preamble	varies	-	events	Track events begin here.
After Events	0-3	-	Padding	Padding to align the end of the track on 4 bytes. The value is usually the terminating 0x98 byte repeated as needed, up to 3 extra times.

Example

Here's an example "Events" section (it does not include the preamble and header):

 E3 73 A4 82 93 E0 1F 98 

It ends on an offset divisible by 4, so there is only a single 0x98 event at the end.

Here's what would happen if we'd add an extra events. Lets copy the 0xE3 event and its parameter once:

 E3 73 E3 73 A4 82 93 E0 1F 98 98 98

..we needed to add 2 extra 0x98 events to make the track end on an offset divisible by 4!

Eoc Chunk

---

The EoC chunk marks the end of the SMDL file/container.

Total length 16 bytes

Offset	Length	Type	Name	Description
0x0	4	-	ChunkID	The chunk ID "eoc\0x20" {0x65, 0x6F, 0x63, 0x20}
0x4	4	uint32	Param1	Unknown meaning, is often 0x00000001.
0x8	4	uint32	Param2	Unknown meaning, is often 0x04FF0000.
0xC	4	uint32	Length	Always 0, for end of content chunks.

DSE Events

Tracks are filled with events. Each event starts by a single byte containing a code, which indicates to the sequencer what to do.

• Their value ranges from 0x0 to 0xFF.
• Values from 0x0 to 0x7F are reserved for the PlayNote event.
• Values from 0x80 to 0x8F are reserved for fixed duration pause events.
• Values from 0x90 to 0xFF all have their unique event assigned to them.

PlayNote(0x0 to 0x7F)

The play note event is special in that its format is particular.

• The event code itself is the velocity(0x0 - 0x7F) of the note to be played.
• The first parameter byte is obligatory, and it contains info on whether we modify the track's current octave, how many extra parameters are there, and what note to play.
• The second parameter is optional, and its length varies depending on the length specified in the obligatory parameter. It contains the duration the key is "held down" before being released.

Here's a breakdown of the NoteData byte:

Bits	Name	Meaning
1100 0000	OctaveMod	A value from 0 to 3 from which 2 is subtracted. The result is a signed value that we add to the track's current octave.
0011 0000	NbParamBytes	A value from 0 to 3 which indicates the amount of extra parameter bytes that should be read.
0000 1111	Note	The Note that should be played at the track's current octave(after OctaveMod).

Note List

Value	Note Name
0x0	C
0x1	C#
0x2	D
0x3	D#
0x4	E
0x5	F
0x6	F#
0x7	G
0x8	G#
0x9	A
0xA	A#
0xB	B
0xF	Unknown

Example Event

Velocity	NoteData	(Opt)KeyDownDuration
0x7F	0x65	0x20	0x01	0x10

This event will play the note F, at the current track octave with no modifications, and hold the note for 0x100120 ticks.

Fixed Duration Pause(0x80 to 0x8F)

The fixed duration pause is a pause event based on the duration of common musical time intervals. Its event code goes from 0x80-0x8F.

Here's a table of the possible durations:

Code	Musical Time Interval	Duration in Ticks
0x80	Half Note	96
0x81	Dotted Quarter Note	72
0x82	2/3 of a Half Note (Half Note as part of a triplet?)	64
0x83	Quarter Note	48
0x84	Dotted 8th Note	36
0x85	2/3 of a Quarter Note (Quarter Note as part of a triplet?)	32
0x86	8th Note	24
0x87	Dotted 16th Note	18
0x88	2/3 of a 8th Note (8th Note as part of a triplet?)	16
0x89	16th Note	12
0x8A	Dotted 32nd Note	9
0x8B	2/3 of a 16th Note (16th Note as part of a triplet?)	8
0x8C	32nd Note	6
0x8D	Dotted 64th Note	4
0x8E	2/3 of a 32nd Note (32th Note as part of a triplet?)	3
0x8F	64th Note	2

Others(0x90 to 0xFF)

Here is a list of all known events :

Code	Parameter Length	Parameters	Name	Description
0x90	0	-	RepeatLastPause	Pause the track processing for the duration of the last pause.(Includes fixed duration pauses)
0x91	1	(uint8)Duration	AddToLastPause	Pause the track processing for the duration of the last pause + the duration in ticks specified.(Includes fixed duration pauses)
0x92	1	(uint8)Duration	Pause8Bits	Pause the track processing for the duration in ticks.
0x93	2	(uint16)Duration	Pause16Bits	Pause the track processing for the duration in ticks.
0x94	3	(uint24)Duration	Pause24Bits	Pause the track processing for the duration in ticks.
0x95	1	(uint8)CheckInterval	PauseUntilRelease	Pause the track processing as long as a note is held down. Will wait for at least "CheckInterval" ticks, then checks every "CheckInterval" ticks if all notes have been released on the current track.
0x96	0	-	INVALID	Disable current track.
0x97	0	-	INVALID	Disable current track.
0x98	0	-	EndOfTrack	Marks the end of the track. Is also used as padding to align the end of the track on 4 bytes.
0x99	0	-	LoopPoint	Marks the point the track will loop to after the end of track is reached.
0x9A	0	-	INVALID	Disable current track.
0x9B	0	-	INVALID	Disable current track.
0x9C	1	??	??	??
0x9D	0	??	??	??
0x9E	0	??	??	??
0x9F	0	-	INVALID	Disable current track.
0xA0	1	(uint8)Octave	SetTrackOctave	Sets the current track's octave to the value specified. Valid range is 0 - 9.
0xA1	1	(uint8)Octave	AddToTrackOctave	Adds the value specified to the current track octave.
0xA2	0	-	INVALID	Disable current track.
0xA3	0	-	INVALID	Disable current track.
0xA4	1	(uint8)TempoBPM	SetTempo	Sets the track's tempo in beats per minute.
0xA5	1	(uint8)TempoBPM	SetTempo	Sets the track's tempo in beats per minute? (The code is identical to 0xA4)
0xA6	0	-	INVALID	Disable current track.
0xA7	0	-	INVALID	Disable current track.
0xA8	2	??	??	??
0xA9	1	??	??	??
0xAA	1	??	??	??
0xAB	0	-	SkipNextByte	Skips processing the next byte.
0xAC	1	(uint8)ProgramID	SetProgram	Change the track's program(Instrument Preset) to the one specified.
0xAD	0	-	INVALID	Disable current track.
0xAE	0	-	INVALID	Disable current track.
0xAF	3	??	??	??
0xB0	0	??	??	??
0xB1	1	??	??	??
0xB2	1	??	??	??
0xB3	1	??	??	??
0xB4	2	??	??	??
0xB5	1	??	??	??
0xB6	1	??	??	??
0xB7	0	-	INVALID	Disable current track.
0xB8	0	-	INVALID	Disable current track.
0xB9	0	-	INVALID	Disable current track.
0xBA	0	-	INVALID	Disable current track.
0xBB	0	-	INVALID	Disable current track.
0xBC	1	??	??	??
0xBD	0	-	INVALID	Disable current track.
0xBE	1	??	??	??
0xBF	1	??	??	??
0xC0	1	??	??	??
0xC1	0	-	INVALID	Disable current track.
0xC2	0	-	INVALID	Disable current track.
0xC3	1	??	??	??
0xC4	0	-	INVALID	Disable current track.
0xC5	0	-	INVALID	Disable current track.
0xC6	0	-	INVALID	Disable current track.
0xC7	0	-	INVALID	Disable current track.
0xC8	0	-	INVALID	Disable current track.
0xC9	0	-	INVALID	Disable current track.
0xCA	0	-	INVALID	Disable current track.
0xCB	2	-	SkipNext2Bytes	Skip processing the next 2 bytes.
0xCC	0	-	INVALID	Disable current track.
0xCD	0	-	INVALID	Disable current track.
0xCE	0	-	INVALID	Disable current track.
0xCF	0	-	INVALID	Disable current track.
0xD0	1	??	??	??
0xD1	1	??	??	??
0xD2	1	??	??	??
0xD3	2	??	??	??
0xD4	3	??	??	??
0xD5	2	??	??	??
0xD6	2	??	??	??
0xD7	2	(uint16)Bend	PitchBend	Bend the pitch of the note.
0xD8	2	??	??	??
0xD9	0	-	INVALID	Disable current track.
0xDA	0	-	INVALID	Disable current track.
0xDB	1	??	??	??
0xDC	5	??	??	??
0xDD	4	??	??	??
0xDE	0	-	INVALID	Disable current track.
0xDF	1	??	??	??
0xE0	1	(int8)TrackVolume	SetTrackVolume	Change the track's volume to the value specified. (0x0-0x7F)
0xE1	1	??	??	??
0xE2	3	??	??	??
0xE3	1	(int8)TrackExpression	SetTrackExpression	Change the track's expression(secondary volume) to the value specified. (0x0-0x7F)
0xE4	5	??	??	??
0xE5	4	??	??	??
0xE6	0	-	INVALID	Disable current track.
0xE7	1	??	??	??
0xE8	1	(int8)Pan	SetTrackPan	Change the track's pan to the value specified. (0x0-0x7F. 0x40 is middle, 0x0 full left, and 0x7F full right )
0xE9	1	??	??	??
0xEA	3	??	??	??
0xEB	0	-	INVALID	Disable current track.
0xEC	5	??	??	??
0xED	4	??	??	??
0xEE	0	-	INVALID	Disable current track.
0xEF	1	??	??	??
0xF0	5	??	??	??
0xF1	4	??	??	??
0xF2	2	??	??	??
0xF3	3	??	??	??
0xF4	0	-	INVALID	Disable current track.
0xF5	0	-	INVALID	Disable current track.
0xF6	1	??	??	??
0xF7	0	-	INVALID	Disable current track.
0xF8	0	-	SkipNext2Bytes2	Skips processing the next 2 bytes.
0xF9	0	-	INVALID	Disable current track.
0xFA	0	-	INVALID	Disable current track.
0xFB	0	-	INVALID	Disable current track.
0xFC	0	-	INVALID	Disable current track.
0xFD	0	-	INVALID	Disable current track.
0xFE	0	-	INVALID	Disable current track.
0xFF	0	-	INVALID	Disable current track.

Credits

• TruePikachu for some of the details on the SMDL format! [1]
• The unknown Japanese author of the "smd2mid v0.10" utility floating around the web.