Pattern Effects
These are the new (0.70 and later) effects. Songs made with earlier versions of DreamTracker will be converted during loading.
Work is still being done to implement the listed effects which can be tracked by looking at the “Implemented” column of the effect lists.
To see proposed effects, take a look at this Google Doc
Pattern effects are used to modulate sounds in various ways and can be used in both patterns as well as (if/once supported) tables.
Effects have a byte parameter and a byte value. For instance 1234 would
be effect 12 with a value of 34.
Effects are currently divided into 3 groups:
- Shared Effects: These are effects that work basically the same way across multiple sound options (typically PSG and FM though some effects also operate on PCM)
- Unique Effects: Effects which are unique to the soundchip where the parameters values are reused across the sound options but do different things.
- Global Effects: Effects which operate on the entire song. The parameters are the same regardless of the channel they are used in.
Shared Effects
| Hex | Effect | Supported | Persistent | Implemented |
|---|---|---|---|---|
| 00xx | Pitch Slide Down | PSG/FM/PCM | No | PSG/FM |
| 01xx | Pitch Slide Up | PSG/FM/PCM | No | PSG/FM |
| 02xx | Pitch Sweep Down | PSG/FM/PCM | Yes | PSG/FM |
| 03xx | Pitch Sweep Up | PSG/FM/PCM | Yes | PSG/FM |
| 04xx | Volume Slide Down/Up | PSG/FM/PCM | No | PSG |
| 05xx | Volume Sweep Down/Up | PSG/FM | Yes | PSG |
| 06xx | Glissando (Glide) | PSG/FM | Yes | PSG/FM |
| 07-x | Legato | PSG/FM | Yes | PSG/FM |
| 08xy | Vibrato | PSG/FM/PCM | Yes | PSG |
| 09xy | Tremolo | PSG/FM/PCM | Yes | PSG |
| 0Axy | Arpeggio | PSG/FM | Yes | PSG |
| 0Bxy | Arp Direction / Speed | PSG/FM | Yes | PSG |
| 0Cxx | Panolo | PSG/FM | Yes | No |
| 0Dxx | Volume | PSG/FM/PCM | Yes | No |
| 0Exy | Pan | PSG/FM | Yes | No |
| 0Fxx | Note Cut | PSG/FM/PCM | No | No |
| 10xx | Note Delay | PSG/FM/PCM | No | PSG |
| 11xx | Channel Attenuation | PSG/FM/PCM | Yes | No |
| 12– | Reset Channel | PSG/FM/PCM | No | PSG/FM |
| 13xx | Set Table | PSG/FM | Yes | No |
| 14xx | Set Table Speed | PSG/FM | Yes | No |
| 15xx | Set Table Loop Mode | PSG/FM | Yes | No |
| 16xx | Run Macro | PSG/FM | No | No |
Vibrato/Tremolo/Pulsolo (LFOs)
Vibrato, Tremolo, and Pulsolo all work slightly differently than in other trackers.
You can think of it as a triangle ramp with x as length and y as depth.
Unlike most other trackers, the lower the value of x, the
faster the speed. The depth is actually how much to add or subtract from the root value.
Under the covers, x is the length of the ramp in one direction. When the effect is
first enabled, the length counter is divided by 2 to make the effect more centered
on the root. One each synth tick, the value of y is either added or subjected to the root
depending on the ramp direction. The direction flips every-time the loop completes.
y | /\ /\ | / \ / \ | / \ / \ | / \ / \ | / \/ \ +----------------------- x
This means x and y are somewhat coupled together.
The reason for this approach is it results in small and efficient code and allows the potential for other modifications to the LFOs in the future.
Vibrato and Pitch Shift Multiplier (PSG)
The PSG vibrato responds to the instrument/channel pitch speed multiplier. This can be used to great vibratos of a higher range than normal and even create some wild arcade style sound effects.
Legato
Continue automation while playing additional notes. For PSG, this means LFOs, envelopes, etc. all continue to run. For FM it skips the note-off before note-on.
Arp Direction / Speed
First value controls direction. If 0, arp goes up; if 1, arp goes down. Second value controls speed, higher values mean slower arp, behaving much like the song speed.
Unique Effects
VERA PSG
Note this list is not yet complete.
| Hex | Effect | Persistent | Implemented |
|---|---|---|---|
| 40xx | Frequency Word Low | No | Yes (1) |
| 41xx | Frequency Word High | No | Yes (1) |
| 42xx | Pan and Volume | No | Yes (1) |
| 43xx | Wave and Pulse | No | Yes (1) |
| 44xx | Wave Width | Yes | Yes |
| 45xx | Wave Slide | No | Yes |
| 46xx | Wave Sweep Down/Up | Yes | Yes |
| 47xx | Pulsolo/Wavolo | Yes | Yes |
| 48xx | Finetune | Yes | Yes |
| 49xx | Finetune Mode | Yes | No |
| 4Axx | Pitch Speed Multiplier | Yes | Yes |
- Effects
$40-$43are directly mapped to the VERA’s channel registers. At present due to how the synth engine works, they may not work as expected and it’s recommended to use other effects.
Finetune
Finetune is signed so 10-70 is finetune up, F0-80 is finetune down. At present,
the second digit does not have an affect. Finetune triggers on the current note, if
a note is provided with the effect; or the next note played.
Pitch Speed Multiplier
This sets the pitch speed multiplier for the channel and works the same way as the pitch speed multiplier of a PSG instrument. It changes the speed pitch envelopes, sweeps, glide and vibrato are evaluated it.
The value is how many left-shifts to move the given values.
VERA Volume Column Effects
Since the volume range of the VERA is 00-3F, the upper values
can be used for other things, such as panning, changing the wave
or setting the PWM.
| Range | Function |
|---|---|
| 00-3F | Volume |
| 40-7F | Channel Attenuation |
| 80-BF | Set PWM |
| C0 | Pan Center |
| C1 | Pan Left |
| C2 | Pan Right |
| C3 | Set Wave to Pulse |
| C4 | Set Wave to Saw |
| C5 | Set Wave to Tri |
| C6 | Set Wave to Noise |
The range 40-7F is used to set attenuation. This value is subtracted
from the channel volume before it is written out to the VERA. This can
be extremely useful if wanting to, for example, use multiple channels
to simulate delay. The attenuation is always applied to the volume
and is global to the channel.
FM (YM2151)
Effects $40-57 are directly mapped to the YM2151’s channel registers.
Some effects may change multiple things. Consult
Chapter 11 of the X16 Reference Docs for how these are organized.
The DreamTracker website keeps a mirror of the reference docs in
mkdocs format here.
| Hex | Effect | Persistent | Implemented |
|---|---|---|---|
| 40xx | M1 Fine Detune and Frequency Mult | Yes | Yes |
| 41xx | M2 Fine Detune and Frequency Mult | Yes | Yes |
| 42xx | C1 Fine Detune and Frequency Mult | Yes | Yes |
| 43xx | C2 Fine Detune and Frequency Mult | Yes | Yes |
| 44xx | M1 Volume | Yes | Yes |
| 45xx | M2 Volume | Yes | Yes |
| 46xx | C1 Volume | Yes | Yes |
| 47xx | C2 Volume | Yes | Yes |
| 48xx | M1 Key Scale and Attack | Yes | Yes |
| 49xx | M2 Key Scale and Attack | Yes | Yes |
| 4Axx | C1 Key Scale and Attack | Yes | Yes |
| 4Bxx | C2 Key Scale and Attack | Yes | Yes |
| 4Cxx | M1 AM Enable and Decay 1 Rate | Yes | Yes |
| 4Dxx | M2 AM Enable and Decay 1 Rate | Yes | Yes |
| 4Exx | C1 AM Enable and Decay 1 Rate | Yes | Yes |
| 4Fxx | C2 AM Enable and Decay 1 Rate | Yes | Yes |
| 50xx | M1 Coarse Detune and Decay 2 Rate | Yes | Yes |
| 51xx | M2 Coarse Detune and Decay 2 Rate | Yes | Yes |
| 52xx | C1 Coarse Detune and Decay 2 Rate | Yes | Yes |
| 53xx | C2 Coarse Detune and Decay 2 Rate | Yes | Yes |
| 54xx | M1 Sustain and Release | Yes | Yes |
| 55xx | M2 Sustain and Release | Yes | Yes |
| 56xx | C1 Sustain and Release | Yes | Yes |
| 57xx | C2 Sustain and Release | Yes | Yes |
| 58xx | Pan, Feedback and Algorithm | Yes | No |
| 59xx | Mod Sense (Vibrato/Tremolo) | Yes | No |
| 5Axx | LFO Waveform | Yes | Yes |
| 5Bxx | LFO Frequency | Yes | Yes |
| 5Cxx | LFO AM/PM Depth | Yes | Yes |
| 5Dxx | Ch. 7 Noise Control | Yes | Yes |
| 5Exx | Global To Operator Volume | Yes | No |
FM Volume Column Effects
Since the volume range of the YM2151 is 00-7F, the remaining range
will likely end up being used for channel attenuation. For now values
above 80 don’t do anything (though it’s recommended not to use them
as they will be allocated to something in the future).
| Range | Function |
|---|---|
| 00-7F | Volume |
PCM
TBD
Global Effects
| Hex | Effect | Persistent | Implemented |
|---|---|---|---|
| C0– | Stop Song | No | Yes |
| C1xx | Song Speed | No | Yes |
| C2xx | Pattern Break | No | Yes |
| C3xx | Jump to Order | No | Yes |
| C4xx | Jump to Row | No | No |
| C5xx | Global Transpose | No | Yes |
| C6xx | Set BPM (VIA Only) | No | No |
| C7xx | Set Engine Speed (VIA/MIDI) | No | No |
Slides and Sweeps
Slides are single shot. That is to say, they run once when you put specify the effect for a channel. If you want the effect to fire multiple times, you have to specify it. This is by design because it allows for intentional coarse stair-step style sounds as well as slicer/stacatto, among other things.
Sweeps, however, are continual and run until they are turned off
by specifying 00 (for example 0500). They also run at the same
speed as the sound engine which means they are much smoother and
faster. They can be thought of like a simple linear envelope in this
way. If you want to make a kick-drum from a square-wave, you’ll
want to use a sweep.
Some effects combine slide/sweet and direction in one command. This is because the VERA only supports volume and PWM from 00-3F. We can use the top bits to add more function. If that sounds complicated, don’t worry, just use the table below:
| Range | Function |
|---|---|
| 00-3F | Slide/Sweep Down |
| 40-7F | Slide/Sweep Up |