Ubuntu Manpage: qmidiarp - MIDI arpeggiator and LFO

NAME

       qmidiarp - MIDI arpeggiator and LFO

SYNOPSIS

       qmidiarp [OPTION] [file]
       qmidiarp { --help | --version }

DESCRIPTION

QMidiArp is an advanced MIDI arpeggiator, programmable step sequencer and LFO. It runs with either JACK
MIDI or ALSA MIDI. It can hold any number of arpeggiator or LFO modules running in parallel. The
arpeggiator modules produce sequences depending on the notes sent to their input port, which is typically
connected to a keyboard or another sequencer. The step sequencer modules allow you to create simple
linear, monophonic and globally transposable sequences similar to the first analog sequencers. The MIDI
LFOs independently produce MIDI controller data of adjustable waveform, time resolution, amplitude and
duration. For each module, an input note filter is available, and the output port and channel can be set
independently. Since the modules use a common sequencer queue, they are automatically in sync with each
other. QMidiArp works with an internal tick resolution of 192 ticks per beat. The queue can be
synchronized to an incoming MIDI realtime clock or as a JACK transport client. Most of the relevant
control elements are accessible via MIDI controller through a MIDI-learn infrastructure. QMidiArp also
has a log tool displaying the history of incoming MIDI events in colors depending on their type.
QMidiArp is based on the Qt4 toolkit.

General Operation
When no commandline options are given, QMidiArp starts as a JACK MIDI client with an input port and two
output ports. For starting QMidiArp as an ALSA client, use the -a option. A new arpeggiator or LFO
module can be created by clicking one of the Add Arp..., Add LFO... or Add Step Sequencer... buttons,
which will show a new tab with the chosen module in the main area. The modules can be renamed or removed
using the corresponding buttons or menu functions. Modules can be detached from the main window to
control and view them in parallel. They can be brought back to the main window again by clicking on the
icon on the left side of each module title bar. They can also be aligned side-by-side within the same
window if the main window is stretched sufficiently before reinserting a module. The entire setup
containing all arps, sequences and LFOs in the tab bar along with the parameters set in the Settings
window can be saved to or loaded from a QMidiArp XML file (.qmax). The tempo of the queue can be set in
beats per minute and affects all modules. The queue is started and stopped by the blue arrow button.

MIDI Clock operation (ALSA MIDI only)
In ALSA mode, QMidiArp runs using its own clock and tempo, but it can optionally use incoming MIDI clock
events as clock and start/stop control source. If the MIDI clock button right of the tempo box is
pressed, the running ALSA queue is stopped, and QMidiArp will wait for an incoming "MIDI Clock Start"
event from an external source connected to QMidiArp's MIDI input. Once this event is received, the queue
is started using MIDI realtime clock events as clock source. QMidiArp will best remain in sync with the
incoming MIDI clock if its internal tempo value (see above) approximately corresponds to that of the
incoming clock. The MIDI clock tempo is, however, measured while the queue is running. Therefore, if the
tempos of the MIDI clock and that of QMidiArp differ, synchronization should become stable from the
second queue start. The queue will stop when a MIDI Clock Stop event is received. During MIDI Clock
operation, QMidiArp's own clock start and stop functions as well as adding or loading new setups are
disabled. They are enabled again by unchecking the MIDI clock button.

JACK Transport Client Operation
When the Jack Transport Connect button is pressed, QMidiArp will try to connect to a running Jack server
and then function as a Jack Transport client, i.e. set its tempo and remain synchronized to a running
Jack Transport master. Note that QMidiArp will restart its queue from zero whenever Jack transport is
starting regardless of Jack Transport's position. This also applies in case of a looping Jack Transport
queue. The Jack button will be released automatically if QMidiArp gets disconnected from Jack by a
possible Jack shutdown or if Jack is not available at connection time.

Note: MIDI Clock and Jack Transport button states will be saved with the QMidiArp session file, and get
active or inactive when a new session file is loaded.

Arpeggiator Modules
QMidiArp's arpeggiators can produce complex patterns derived from the notes played on a MIDI keyboard.
QMidiArp's arpeggiator modules were inspired by the MAP1 hardware arpeggiator by Rudi Linhard.

Input and Output panels

Each arpeggiator has an Input and an Output panel. The Input panel defines the note range and the MIDI
channel to which the arp is assigned. Notes that pass this Input filter are sorted by pitch and added to
the internal note buffer of the arpeggiator. Incoming notes that do not match any filter can either be
discarded or forwarded to a selectable MIDI port (see Settings ). The Output panel holds settings for the
MIDI channel and output port to which the arpeggiator notes will be sent.

Arpeggiator Patterns

Arpeggio patterns can be selected and edited in the Pattern panel. Pattern presets are selectable from a
combo box. The currently active pattern is displayed as a piano roll type screen showing the base notes
as streaks. The y-scale of the graphics window corresponds to the index of the notes in the pattern.
Octave changes (see Editing patterns ) are shown as additional horizontal lines. The notes that are
eventually sent depend on the input notes received by the arpeggiator. The received notes notes are
attributed in ascending order to the notes defined in the pattern. For example, a single streak on the
bottom of the arp display ("simple" presets) means that at the first pass through the pattern, the
lowermost note played on the keyboard is played. If a chord is played on the keyboard and only one note
is present in the pattern, only the lowermost pressed note is output at the first pass through the
pattern. For the following repetitions of the pattern, the chosen "repeat mode" is used to determine the
following notes. If the pattern contains stacked note streaks (chord mode), chords played on the
keyboard are also output as chords with polyphony up to the number of notes defined in the stack.

Repeat Mode

This setting defines the behavior of the arpeggio over several repetitions of the pattern when the number
of notes pressed on the keyboard is higher than the number of notes present in the pattern. When Repeat
Mode is "Up", the next higher note played on the keyboard is played at each repetition. With "Down", the
next lower note is played. With a single note present in the arp pattern, this creates classical linear
arpeggios. This way even simple patterns like "01" (or even "0") will generate a complete arpeggio. When
"Static" is selected, this classical arpeggio mode will be disabled, and the output notes remain
constant.

Trigger mode

QMidiArp's arpeggiators can run in three modes. "No trigger" will cause the arp running continuously in
synchronization with the internal or external clock source. Even when new notes are played, they will be
output quantized to the running queue. "Kbd restart" will cause a reset of the playhead position upon the
next note to be output, but the output pattern stays quantized to the queue. When "Kbd trigger" is
selected, each new note played in stakato will trigger the pattern with the timing of the played note.

Editing Arp patterns

Arp patterns are defined by a text sequence containing the notes themselves as numbers along with control
changes for chord, tempo, velocity and octave changes. When the Edit pattern button in the pattern panel
is clicked, the current pattern preset appears as a text input line. The edited pattern can be stored in
the preset list by clicking on the Store pattern button. The currently active pattern can be removed from
the preset list by clicking on the Remove pattern button. All preset patterns are immediately saved in
the .qmidiarprc resource file when a pattern is stored or removed, and the new pattern list is made
available to the other arps in the tab bar. Pattern presets are automatically loaded on each application
start.

The syntax for the pattern text is as follows:

0..9 : Note indices
+ : One octave up
- : One octave down
= : Reset to standard octave
> : Double tempo
< : Half tempo
. : Reset to standard tempo
( ) : Chord, begin..end,
e.g. (012) would be a chord of the
lowermost three notes in the buffer
/ : Volume up by 20%
\ : Volume down by 20%
d : Double length
h : Half length
p : Pause

Any token is valid until the end of a pattern is reached. The token > will e.g. double the tempo for all
following notes of the pattern. When the loop jumps back to the beginning of the pattern, the tempo is
reset to its initial value, i.e. a quarter note.

Random

The timing, velocity and length of the output notes can be randomized using the sliders in the Random
panel. These settings can be used to make the arpeggiator sound less mechanical, but if they are set to
higher values, they add interesting accents to the patterns.

Envelope

QMidiArp can modulate the velocity of the arpeggios with an envelope function defined by Attack time and
Release time. If an attack time is set, the velocities of the output notes are ramped up during the
attack time defined in seconds. If a release time is set, notes released from the keyboard are continued
to be output while their velocity is ramped down linearly and until the release time has reached its end.
The envelope function only makes sense if the sound driven by the arp is velocity-sensitive. It works
best with highly polyphonic patterns such as "Chord Oct 16 A".

Groove

The Groove sliders control a linear shift of timing, length and velocity within each beat of the output
pattern. This can be used to create swing timing and accent. The Groove settings are adjusted for all
arps simultaneously.

LFO Modules
In parallel to the arps, QMidiArp can send MIDI controller data in form of a low frequency oscillator
(LFO) to the assigned output. The LFO data consist of controller events that are in sync with the
arpeggiator queue. The queue has to be in running state to enable the LFO. Each LFO module has a waveform
panel to define the shape of the outgoing data and an output panel to define MIDI Channel, ALSA port and
controller number to be produced. The waveform can currently be set to Sine, Saw Up, Saw Down, Triangle,
Square and Custom. The frequency of the LFO can be set in muliples and divisors of the arp tempo, such
that frequency of 1 produces one full wave per beat. If frequencies lower than 1 are selected, the length
of the wavetable has to be adjusted correspondingly to produce a full wave. The time resolution of the
LFO determines the number of events produced every beat and can be adjusted to up to 192 events per beat.
Amplitude and offset of the waveform can be adjusted from 0...127. Low resolutions lead to audibly
discrete rythmic controller changes whereas higher resolution values lead to more continuous waves.

Muting individual wave points

Individual wave points can be muted/unmuted by clicking on the corresponding location in the wave display
with the right mouse button. A muted wave point is shown in darker color.

Custom Waveforms

When Custom is selected, the waveform can be drawn with the left mouse button in the waveform display. A
calculated waveform is copied to the custom waveform whenever it is being modified by the mouse. This
will overwrite the previous custom waveform with the currently displayed waveform. As all LFO operations,
drawing and muting can be done while the queue is running, and becomes effective immediately.

Play direction and looping

The play mode can be switched between:

->_> : Forward and Loop
<_<- : Backward and Loop
->_< : Forward and Bounce
>_<- : Backward and Bounce
->_| : Forward Single shot
|_<- : Backward Single shot

The direction and loop settings apply immediately when changed on the fly.

Recording

The LFO records incoming controller data as selected in the Input panel, when the Record button is
pressed. Note that the Record button itself can be attributed to a MIDI toggle controller so that it
provides a convenient implementation of a controller motion sampler and looper.

LFO Input panel

The input panel contains settings on which MIDI CC is to be recorded, how the LFO acts to note events
received on the input. As the arpeggiators, the LFO can be restarted or (re-) triggered by notes played
on the keyboard, and the wave output can be stopped or not when Note Off events are received on the input
Channel

LFO Output panel

The LFO output panel contains the port, channel and controller number settings of the LFO data produced
by each LFO tab. You can also mute each LFO wave.

Step Sequencer Modules
By clicking Add Step Sequencer... in the control tool bar, a new Seq module can be added to the tab bar.
Each of these modules produce a simple linear (monophonic) sequence, similar to the first analog hardware
sequencers. The Seq modules are controllable while running, also in a similar way to analog step
sequencers.

Programming a sequence

As QMidiArp's LFO modules, the step sequencer can be programmed by adjusting notes with left mouse clicks
on the sequence display. The octave range is fixed to 4. The lowest note is C2 if the global transpose is
set to 0. Notes can be muted with the right mouse click. The sequence length can be adjusted between 1
and 8 beats, and the time resolution can be set to values between 1 and 16 per beat. A resolution of 4
means that 4 notes are output every beat, i.e. sixteenth notes. The sequence can also be programmed
using the Record function. When the Record button is pressed, notes received on the input port will be
recorded step-by-step starting from the last modified note. Programming can be done on the fly also when
the sequencer queue is running.

Controlling the sequence globally

There are sliders to adjust the global velocity (volume), note length and transpose of the sequence in
semitones.

Seq Input and Output panels

The Seq Input panel determines how to handle incoming notes on the MIDI Channel set in the channel box.
If Note is checked, the sequence will be globally transposed with the incoming note as transpose value.
If Velocity is checked in addition, the sequence will output notes with the same velocity as that
received on its input. The Input panel also determines how the sequence behaves when incoming notes are
received. It can be restarted, triggered and stopped with the timing of received notes as the LFO
modules.

The Seq Output panel is equivalent to that of arpeggiator and LFO modules.

Note that accents within a pattern can be produced by running LFO modules in parallel to the Seq module,
and by sending to the same channel and port as the Seq module.

Settings
The Settings window allows one to configure if and to which port incoming events that do not match any
module's input filter are forwarded ( unmatched events). It also allows one to set whether incoming
controller events are recognized for muting and controlling the modules separately. If this option is
set, QMidiArp will recognize MIDI control events that can be attributed to different parameters (see MIDI
Control ). By checking the compact module style all new created modules will show with small GUI elements
to be more economic in space when distributed as separate windows over the desktop.

All settings in this dialog are stored along with the module data in the qmax session file.

MIDI control
QMidiArp supports MIDI control events if the Modules controllable by MIDI CC option is checked in the
Settings dialog.

MIDI Learn

Controllers can be attributed by right-clicking on the sliders or mute checkbox in each module and
selecting MIDI Learn. QMidiArp will then wait for MIDI control events, and moving a MIDI controller
connected to QMidiArp's input will attribute this controller to the control item. It is possible to add
several MIDI controllers to one item. If MIDI Forget is selected, all controllers for that item are
removed. If Cancel MIDI learning is selected, the learn process is stopped.

Note that by default, mute controllers are interpreted as toggles, i.e. the mute state is toggled on
reception of a value of 127 from the attributed controller.

Control Editor

The Control Editor is accessible from the View menu. Controls can be edited by MIDI control number,
channel, and the minimum and maximum values that are sent to the control item. Mute controllers have a
special behaviour. If minimum and maximum are equal, the controller acts as toggler upon reception of the
adjusted value. If minimum is different from maximum, the corresponding module will be muted upon
reception of minimum and unmuted upon reception of maximum as values.

If Remove is pressed, the currently selected line will be removed, pressing Revert reloads the current
controller settings. Pressing Cancel quits the control editor without applying changes, and only if OK is
pressed, the edited control list becomes active.

Global Storage
There is another dock window available for storing and restoring most of the parameters of all modules at
once. In this window, each module and its storages appear as a column, the first column representing
switches for all modules globally. When the small Store button on the left is clicked, all modules will
store their parameters in a location given by the current row, and the next available storage location
appears. Module storages can be recalled by clicking on the buttons of each individual module or globally
(numbered buttons in the first column). Storage locations can be removed again by clicking on the "arrow"
button on the bottom of the list. When a new module is added at a time when storage locations already
exist for other modules, the storage locations for the new module will be empty and can be filled by
using Store again at this location.

When QMidiArp is running, the switch behavior will depend on the selection made in the comboboxes in the
first row of the window.

End of will cause parameter switches to occur when the module in the second combobox reaches its pattern
end. When individual switches are done the module in the column of the clicked module determines the
switch time.

After will do parameter switches at the end of the number of beats selected in the second combobox after
the restore button is clicked.

The switch can be done by MIDI controller assigned by the MIDI Learn context menu of the top button of
each column. Note that it is the the controller value that corresponds to the storage location, and that
you may want to adjust the range of controllers to your needs using the MIDI Control Editor With the
Global Storage handler, QMidiArp can act as a simple but handy live sequencer tool. But the Golbal
Storage button in the View menu and in the main toolbar toggles visibility of the Global Storage window.

Event Log
The Event Log displays incoming MIDI events. It is displayed in the bottom area by default, but can be
hidden if not needed or set floating as a top-level window on the desktop. Logging can also be disabled
generally or for MIDI Clock events only.

Example Files
There are currently three demo arpeggios. The demo.qma arpeggio was intended to be used with the
following sound types: Ch 1: Marimba, Ch 2: Celesta, Ch 3: Acoustic Bass, but you can get interesting
results if you use other instrument settings.

The demo_seqlfo.qmax setup shows the use of the new sequencer and LFO modules playing in parallel. The
sequencer outputs should be routed to percussive synthesizer sounds. The LFO data is intended to act on
filter cutoff, which has the standard controller CC#74. ZynAddSubFX by Paul Nasca reacts on these filter
cutoff controllers. The "Bass 1" and "Plucked 3" presets from this synthesizer work well with this demo
file.

OPTIONS

       --portCount <num>
              Set the number of available ALSA output ports to <num>. The default is 2.

       --help Print possible command-line options and exit.

       --version
              Print version information and exit.

       --alsa Use the ALSA MIDI backend

       --jack Use the JACK MIDI backend (default)

       file   Name of a valid QMidiArp (.qmax) XML file to be loaded on start.

FILES

       *.qmax
              QMidiArp XML files containing session data in XML text format.

EXAMPLES

       Example QMidiArp files can be found in /usr/share/qmidiarp or in /usr/local/share/qmidiarp

NOTES

       Errors and warnings are written to stderr(3).

SUPPORT

       qmidiarp-devel@lists.sourceforge.net

AUTHORS

       Frank  Kober,  Nedko  Arnaudov,  Guido Scholz and Matthias Nagorni. This manual page was written by Frank
       Kober <emuse@users.sourceforge.net>.

                                                   2011-11-07                                        QMIDIARP(1)