RhythML is a plaintext format designed to sequence pitch and CV patterns in a eurorack-style environment. The format is agnostic to what you are using each output for, which allows for specifying both rhythmic triggers and melodic sequences in a compact, easily editable, human readable text format. Below is a detailed specification of the RhythML syntax as implemented by the Spellbook VCV Rack module.
- Lines: Each line in the text input corresponds to a sequence step. Steps are processed sequentially with the receipt of each clock signal at the CLOCK_INPUT.
- Columns: Individual values within a line are separated by commas
,. Each column corresponds to one of the 16 outputs. Columns 17 and beyond are ignored (for now).
Each cell in a grid can contain values in one of these formats. Every cell is parsed independently, so you can freely mix and match formats to express intentions and uses in the music.
-
Decimal Voltage Levels:
- Example:
5,-3.5,0.0,12 - Specifies a voltage directly.
- Anything that parses to a floating point number is allowed, but note Eurorack convention is to stay within -10 to +10 volts, with a 10 volt range between min and max value, and some modules may behave strangely or not accept voltages outside their expectations.
- Example:
-
Gate and Trigger Commands:
XorRor_: Outputs 0 volts for the first 1ms of the step, then a high signal (10 volts) for the remainder.- Guarantees a rising edge, regardless of the prior step, and holds a high signal afterward.
Tor^: Outputs 0v for 1ms, then 10v for 1ms, then 0v thereafter.- Guarantees a rising edge, regardless of the prior step, and holds a low signal afterward.
Wor|: Outputs a full width gate signal (10 volts), equivalent to writing10in the cell.- Use this to continue a gate across steps.
- If the output is already high from a prior retrigger or gate, this will NOT create a new rising edge in the signal.
- Gates (as with all signals except for Triggers and Retriggers) are 100% width; two consecutive gates will output a continuous signal with no break or edge.
-
Scientific Pitch Names:
- Format:
<NoteName><Octave> - Example:
C4,G#3,Db5 - Accidentals can be
#for sharp,bfor flat,$for half-sharp, anddfor half-flat. Compound accidentals likeC##(C +2 semitones) orC#$(C +1.5 semitones) are allowed, and accidentals can be on any note, soE#is the same note asFandCbis the same asB. - If no octave is included, but it is still valid note name, a default octave of 4 is used. For example "C" will be read as "C4".
- Outputs a voltage corresponding to the specified musical note, in Eurorack 1V/oct standard, where C4 = 0V, C#4 = 1/12V, ..., B4 = 11/12V, C5 = 1V, C3 = -1V, etc.
- Format:
-
MIDI Note Numbers
- Format:
m<Number> - Example:
m60,m72 - MIDI Note 60 = C4 = 0.0v.
- Decimals and numbers outside the normal MIDI range of 0 to 127 are allowed, but are usually not going to be respected if you try to send those pitches back into a MIDI environment.
- Format:
-
Semitones
- Format:
s<Number> - Example:
s0,s7,s-12 - Decimals are allowed
- Semitones are numbered relative to C4, which means they are basically the same as MIDI Notes except 0 = C4
- Format:
-
Cents
- Format:
<Number>ct - Example:
0ct,7ct,-12ct - Decimals are allowed
- Cents relative to C4
- Format:
-
Hertz
- Format:
<Number>Hz - Example:
440Hz,32Hz,1Hz - Decimals are allowed
- 0 or less is undefined, and will output 0 volts
- Format:
-
Percentages
- Format:
<Number>% - Example:
50%,100%,-12.5% - Numbers ending in % are divided by 10, so that 100% becomes 10.0v, -50% becomes -5.0v, etc.
- This scaling is specific to eurorack. If you are implementing RhythML in another environment, percentages should be translated according to the standards of that environment. For example, if you were parsing RhythML into MIDI, 0%-100% might become 0-127.
- Format:
-
Empty Cells:
- An empty cell or a cell containing only whitespace or comments will leave the output's current voltage as-is, unless that "current voltage" was from a gate, trigger, or retrigger, in which case it reverts to 0.0.
Note that unlike MIDI or a Tracker, a single cell with a pitch in it does NOT automatically generate an associated gate or "note on", it just outputs one voltage to one output, like a CV sequencer. You would need to sequence the rhythm you want using another column, or handle rhythm with another module such as a clock or another sequencer (potentially another Spellbook!). Remember, any column can be for used for anything you need a voltage for: pitches, gates, velocity, CVs, etc. Think modular!
- Any text following a
?in a cell is considered a comment (until the next,) and is ignored during parsing. Comments cannot contain commas.
Example:
5.0 ? This is a comment, 5.5 ? You can put a comment in any cell
Consider using comments as labels:
E4 ? Pitch, X ? Gate, 10 ? Velocity
C5 , X , 8
D5 , X , 6
B4 , X , 5
Or to explain musical intentions:
70% ? Melody volume, 50% ? Backing volume, 0% ? Drum chance, 0% ? Reverb, 35% ? Filter, ? NOTES - Soft start - no drums - slight reverb - mild filter
70% , 50% , 0% , 0% , 35% , ? Continue soft intro
80% , 60% , 30% , 50% , 40% , ? Increase all volumes - introduce drums sporadically
- Whitespace in cell values is ignored.
- Cells are normalized during editing such that each cell in a column has uniform spacing padded with spaces to align columns vertically for readability.
- Blank lines are NOT ignored, and will become new blank rows, with commas added automatically.
Here's a simple RhythML sequence to get started:
E4 ? Pitch, X ? Gate, 10 ? Velocity
C5 , X , 8
D5 , X , 6
B4 , X , 5
In this example, each step sets a pitch in column 1, uses column 2 for gating, and controls a velocity CV in column 3. The sequence plays a C major arpeggio, holding the first note for a full beat, and gradually lowering the velocity on each note. The labels, like ? Pitch, are ignored because of the ?.
Here's the same arpeggio, but with a little more rhythmic variation across 8 steps instead of 4, which you could play at a faster clock speed:
E4 ? Pitch, X ? Gate, 10 ? Velocity
, | ,
, | ,
C5 , X , 8
D5 , X , 6
, ,
B4 , X , 5
, ,
Notice the way this pattern holds notes by using consecutive gates over several steps, using retriggers to ensure a new rising edge for each new pitch.
In general, don't forget you need to explicitly output everything you need, like gates, velocities, CVs, everything! Think, "what would Omri Cohen do?"; think modular!
Watch a brief demonstration here:
These are all available as manufacturer presets in Spellbook.
0 ?A, 0 ?B, 0 ?C, X ?T, T ?Start, ?End
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , ,
0 , 0 , 0 , X , , T
D3 ? Root, F4 ? Third, A4 ? Fifth, X ? Downbeat, ? Upbeat, T ?ChordChange
, , , , X ,
G4 , B5 , D4 , X , , T
, , , , X ,
C4 , E5 , G4 , X , , T
, , , , X ,
, , , X , ,
, , , , X ,
T?Kick, ?Snare, ?Tom1, ?Tom2, ?Rim, ?Clap, T?cHat, ?oHat, ?Crash, ?Ride
, , , , , , , , ,
, , , , , , T , , ,
, , , , , , , , ,
, T , , , , , T , , ,
, , , , , , , , ,
, , , , , , T , , ,
, , , , , , , , ,
T , , , , , , T , , ,
, , , , , , , , ,
T , , , , , , T , , ,
, , , , , , , , ,
, T , , , , , T , , ,
, , , , , , , , ,
, , , , , , , T , ,
, , , , , , , , ,
0.000 ?Sine, 0.625 ?Triangle, -5 ?Saw, 5 ?RevSaw, 5 ?Square, 5 ?ShortPulse, 5 ?LongPulse, 0 ?Noise
0.9755 , 1.2500 , -4.6774, 4.6774 , 5.0000 , 5.0000 , 5.0000 , -5.0000
1.9135 , 1.8750 , -4.3548, 4.3548 , 5.0000 , 5.0000 , 5.0000 , -1.0000
2.7780 , 2.5000 , -4.0323, 4.0323 , 5.0000 , 5.0000 , 5.0000 , 3.0000
3.5355 , 3.1250 , -3.7097, 3.7097 , 5.0000 , 5.0000 , 5.0000 , -2.0000
4.1575 , 3.7500 , -3.3871, 3.3871 , 5.0000 , 5.0000 , 5.0000 , 0.0000
4.6195 , 4.3750 , -3.0645, 3.0645 , 5.0000 , 5.0000 , 5.0000 , -2.0000
4.9040 , 5.0000 , -2.7419, 2.7419 , 5.0000 , 5.0000 , 5.0000 , -4.0000
5.0000 , 4.3750 , -2.4194, 2.4194 , 5.0000 , -5.0000 , 5.0000 , -5.0000
4.9040 , 3.7500 , -2.0968, 2.0968 , 5.0000 , -5.0000 , 5.0000 , -5.0000
4.6195 , 3.1250 , -1.7742, 1.7742 , 5.0000 , -5.0000 , 5.0000 , 4.0000
4.1575 , 2.5000 , -1.4516, 1.4516 , 5.0000 , -5.0000 , 5.0000 , -1.0000
3.5355 , 1.8750 , -1.1290, 1.1290 , 5.0000 , -5.0000 , 5.0000 , 1.0000
2.7780 , 1.2500 , -0.8065, 0.8065 , 5.0000 , -5.0000 , 5.0000 , 5.0000
1.9135 , 0.6250 , -0.4839, 0.4839 , 5.0000 , -5.0000 , 5.0000 , 1.0000
0.9755 , 0.0000 , -0.1613, 0.1613 , 5.0000 , -5.0000 , 5.0000 , -1.0000
0.0000 , -0.6250 , 0.1613 , -0.1613 , -5.0000 , -5.0000 , 5.0000 , -5.0000
-0.9755 , -1.2500 , 0.4839 , -0.4839 , -5.0000 , -5.0000 , 5.0000 , 5.0000
-1.9135 , -1.8750 , 0.8065 , -0.8065 , -5.0000 , -5.0000 , 5.0000 , -2.0000
-2.7780 , -2.5000 , 1.1290 , -1.1290 , -5.0000 , -5.0000 , 5.0000 , 0.0000
-3.5355 , -3.1250 , 1.4516 , -1.4516 , -5.0000 , -5.0000 , 5.0000 , -1.0000
-4.1575 , -3.7500 , 1.7742 , -1.7742 , -5.0000 , -5.0000 , 5.0000 , -2.0000
-4.6195 , -4.3750 , 2.0968 , -2.0968 , -5.0000 , -5.0000 , 5.0000 , -2.0000
-4.9040 , -5.0000 , 2.4194 , -2.4194 , -5.0000 , -5.0000 , 5.0000 , 4.0000
-5.0000 , -4.3750 , 2.7419 , -2.7419 , -5.0000 , -5.0000 , -5.0000 , -4.0000
-4.9040 , -3.7500 , 3.0645 , -3.0645 , -5.0000 , -5.0000 , -5.0000 , 1.0000
-4.6195 , -3.1250 , 3.3871 , -3.3871 , -5.0000 , -5.0000 , -5.0000 , 1.0000
-4.1575 , -2.5000 , 3.7097 , -3.7097 , -5.0000 , -5.0000 , -5.0000 , 5.0000
-3.5355 , -1.8750 , 4.0323 , -4.0323 , -5.0000 , -5.0000 , -5.0000 , -2.0000
-2.7780 , -1.2500 , 4.3548 , -4.3548 , -5.0000 , -5.0000 , -5.0000 , 3.0000
-1.9135 , -0.6250 , 4.6774 , -4.6774 , -5.0000 , -5.0000 , -5.0000 , -3.0000
-0.9755 , 0.0000 , 5.0000 , -5.0000 , -5.0000 , -5.0000 , -5.0000 , 3.0000