               Mysterious's ULTRA TRACKER File Format
                  by FreeJack of The Elven Nation
   (some additional infos on the new format (V1.4/5) by MAS -> * marked)

I've done my best to document the file format of Ultra Tracker (UT).
If you find any errors please contact me.
The file format has stayed consistent through the first four public releases.
At the time of this writting, Ultra Tracker is up to version 1.3
(* With version V1.4/5 there are some changes done in the format. *)

Thanks go to :
SoJa of YLYSY for help translating stuff.

Marc Andr‚ Schallehn
Thanks for putting out this GREAT program.
Also thanks for the info on 16bit samples.

With all this crap out of the way lets get to the format.


Sample Structure :
______________________________________________________________________________
00h Samplename : 32 bytes (Sample name)
20h DosName    : 12 bytes (when you load a sample into UT,
                      it records the file name here)
2Ch LoopStart  : dbl word (loop start point)
30h LoopEnd    : dbl word (loop end point)
34h SizeStart  : dbl word (see below)
38h SizeEnd    : dbl word (see below)
3Ch volume     : byte (UT uses a logarithmic volume setting, 0-255)
                 (* V1.4: uses linear Volume ranging from 0-255 *)
3Dh Bidi Loop  : byte (see below)
3Eh FineTune   : word (Fine tune setting, uses full word value)
______________________________________________________________________________

8 Bit Samples  :

SizeStart  :
The SizeStart is the starting offset of the sample. 
This seems to tell UT how to load the sample into the Gus's onboard memory. 
All the files I have worked with start with a value of 32 for the first sample, 
and the previous SizeEnd value for all sample after that. (See Example below)
If the previous sample was 16bit, then SizeStart = (Last SizeEnd * 2)
SizeEnd : 
Like the SizeStart, SizeEnd seems to tell UT where to load the sample into the 
Gus's onboard memory. SizeEnd equal SizeStart + the length of the sample.

Example :
If a UT file had 3 samples, 1st 12000 bytes, 2nd 5600  bytes, 3rd 8000 byte. 
The SizeStart and SizeEnd would look like this:

Sample        SizeStart         SizeEnd
1st            32                12032
2nd            12032             17632
3rd            17632             25632

***Note***
Samples may NOT cross 256k boundaries. If a sample is too large to fit into the
remaining space, its Sizestart will equal the start of the next 256k boundary.
UT does keep track of the free space at the top of the 256k boundaries, and
will load a sample in there if it will fit.
Example : EndSize = 252144
If the next sample was 12000 bytes, its SizeStart would be 262144, not 252144.
Note that this leaves 10000 bytes unused. If any of the following sample could
fit between 252144 and 262144, its Sizestart would be 252144.
Say that 2 samples after the 12000 byte sample we had a sample that was only
5000 bytes long. Its SizeStart would be 252144 and its SizeEnd would be 257144.
This also applies to 16 Bit Samples.

16 Bit Samples :
16 bit samples are handled a little different then 8 bit samples.
The SizeStart variable is calculated by dividing offset (last SizeEnd)
by 2. The SizeEnd variable equals SizeStart + (SampleLength / 2).
If the first sample is 16bit, then SizeStart = 16.
Example :
          sample1 = 8bit, 1000 bytes
          sample2 = 16bit, 5000 bytes

          sample1 SizeStart = 32
                  SizeEnd   = 1032 (32 + 1000)

          sample2 SizeStart = 516 (offset (1032) / 2)
                  SizeEnd   = 3016 (516 + (5000/2))

***Note***
If a 16bit sample is loaded into banks 2,3, or 4
the SizeStart variable will be
(offset / 2) + 262144 (bank 2)
(offset / 2) + 524288 (bank 3)
(offset / 2) + 786432 (bank 4)
The SizeEnd variable will be
SizeStart + (SampleLength / 2) + 262144 (bank 2)
SizeStart + (SampleLength / 2) + 524288 (bank 3)
SizeStart + (SampleLength / 2) + 786432 (bank 4)

BiDi Loop : (Bidirectional Loop)
UT takes advantage of the Gus's ability to loop a sample in several different
ways. By setting the Bidi Loop, the sample can be played forward or backwards,
looped or not looped. The Bidi variable also tracks the sample
resolution (8 or 16 bit).

The following table shows the possible values of the Bidi Loop.
Bidi = 0  : No looping, forward playback,  8bit sample
Bidi = 4  : No Looping, forward playback, 16bit sample
Bidi = 8  : Loop Sample, forward playback, 8bit sample
Bidi = 12 : Loop Sample, forward playback, 16bit sample
Bidi = 24 : Loop Sample, reverse playback 8bit sample
Bidi = 28 : Loop Sample, reverse playback, 16bit sample
______________________________________________________________________________
Event Structure:
______________________________________________________________________________
0 Note                : byte (See note table below)
1 SampleNumber        : byte (Sample Number)
2 Effect1             : nib (Effect1)
2 Effect2             : nib (Effect2)
3 Effect2Data         : byte
4 Effect1Data         : byte

The High order byte of EffectVar is the Effect variable for Effect1.
The Low order byte of EffectVar is the Effect variable for Effect2.
***(Note)***
UT uses a form of compression on repetitive events. Say we read in the first
byte, if it = $FC then this signifies a repeat block. The next byte is the
repeat count. followed by the event structure to repeat.
If the first byte read does NOT = $FC then this is the note of the event.
So repeat blocks will be 7 bytes long : RepFlag      : byte ($FC)
                                        RepCount     : byte
                                      0 note         : byte
                                      1 samplenumber : byte
                                      2 effect1      : nib
                                        effect2      : nib
                                      3 effectVar    : word

Repeat blocks do NOT bridge patterns. 
______________________________________________________________________________
Note Table:
______________________________________________________________________________
note value of 0 = pause
C-0 to B-0    1 to 12
C-1 to B-1    13 to 24
C-2 to B-2    26 to 36
C-3 to B-3    39 to 48
C-4 to B-4    52 to 60
______________________________________________________________________________
Offset     Bytes            Type                   Description
______________________________________________________________________________
0             15           byte           ID block : should contain
                                                     'MAS_UTrack_V001'
                                          
                                          (* V1.4: 'MAS_UTrack_V002')

                                          (* V1.5: 'MAS_UTrack_V003')

15            32           AsciiZ         Song Title
47            1            reserved       This byte is reserved and
                                          always contain 0;

                                          (* V1.4: jump-value: reserved * 32; 
                                           space between is used for song
                                           text;
                                           [reserved * 32] = RES ! )

48+RES        1            byte           Number of Samples (NOS)
49+RES        NOS * 64     SampleStruct   Sample Struct (see Sample Structure)

Patt_Seq = 48 + (NOS * 64) + RES
                       
Patt_Seq          256        byte            Pattern Sequence
Patt_Seq+256      1          byte            Number Of Channels (NOC) Base 0
Patt_Seq+257      1          byte            Number Of patterns (NOP) Base 0

                                             (* V1.5: PAN-Position Table
                                              Length: NOC * 1byte
                                              [0 left] - [0F right] )

NOC+Patt_Seq+258      varies     EventStruct     Pattern Data (See Event Structure)

______________________________________________________________________________
The remainder of the file is the raw sample data. (signed)
______________________________________________________________________________

That should about cover it. If you have any questions , feel free
to e-mail me at
freejack@shell.portal.com

I can also be contacted on The UltraSound Connection   (813) 787-8644 
The UltraSound Connection is a BBS dedicated to the Gravis Ultrasound Card.

Also I'm the author of Ripper and Gvoc. If anyone has any questions or problems,
please contact me.

