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Csound: PYTHONINCSOUNDQT<span id="XinhaEditingPostion"></span>


If CsoundQt is built with PythonQt support,2  it enables a lot of new possibilities, mostly in three main fields: interaction with the CsoundQt interface, interaction with widgets and using classes from Qt libraries to build custom interfaces in python.

If you start CsoundQt and can open the panels "Python Console" and "Python Scratch Pad", you are ready to go.

The CsoundQt Python Object

As CsoundQt has formerly been called QuteCsound, this name can still be found in the sources. The QuteCsound object (called PyQcsObject in the sources) is the interface for scripting CsoundQt. All declarations of the class can be found in the file pyqcsobject.h in the sources.

It enables the control of a large part of CsoundQt's possibilities from the python interpreter, the python scratchpad, from scripts or from inside of a running Csound file via Csound's python opcodes.3 

By default, a PyQcsObject is already available in the python interpreter of CsoundQt called “q”. To use any of its methods, use form like


The methods can be divided into four groups:

  • access CsoundQt's interface (open or close files, start or stop performance etc)
  • edit Csound files which has already been opened as tabs in CsoundQt
  • manage CsoundQt's widgets
  • interface with the running Csound engine

File and Control Access 

If you have CsoundQt running on your computer, you should type the following code examples in the Python Console (if only one line) or the Python Scratch Pad (if more than one line of code).4 

Create or Load a csd File

Type q.newDocument('cs_floss_1.csd') in your Python Console and hit the Return key. This will create a new csd file named "cs_floss_1.csd" in your working directory. And it also returns an integer (in the screenshot below: 3) as index for this file.

If you close this file and then execute the line q.loadDocument('cs_floss_1.csd'), you should see the file again as tab in CsoundQt.

Let us have a look how these two methods newDocument and loadDocument are described in the sources:

int newDocument(QString name)
int loadDocument(QString name, bool runNow = false)

The method newDocument needs a name as string ("QString") as argument, and returns an integer. The method loadDocument also takes a name as input string and returns an integer as index for this csd. The additional argument runNow is optional. It expects a boolean value (True/False or 1/0). The default is "false" which means "do not run immediately after loading". So if you type instead q.loadDocument('cs_floss_1.csd', True) or q.loadDocument('cs_floss_1.csd', 1), the csd file should start immediately.

Run, Pause or Stop a csd File

For the next methods, we first need some more code in our csd. So let your "cs_floss_1.csd" look like this:

   EXAMPLE 12C01_run_pause_stop.csd

sr = 44100
ksmps = 32
0dbfs = 1
nchnls = 1

giSine     ftgen      0, 0, 1024, 10, 1

instr 1
kPitch     expseg     500, p3, 1000
aSine      poscil     .2, kPitch, giSine
           out        aSine
i 1 0 10

This instrument performs a simple pitch glissando from 500 to 1000 Hz in ten seconds. Now make sure that this csd is the currently active tab in CsoundQt, and execute this:


This starts the performance. If you do nothing, the performance will stop after ten seconds. If you type instead after some seconds


the performance will pause. The same task q.pause() will resume the performance. Note that this is different from executing q.play() after q.pause() ; this will start a new performance. With


you can stop the current performance.

Access to Different csd Tabs via Indices

The play(), pause() and stop() method, as well as other methods in CsoundQt's integrated Python, allow also to access csd file tabs which are not currently active. As we saw in the creation of a new csd file by q.newDocument('cs_floss_1.csd'), each of them gets an index. This index allows universal access to all csd files in a running CsoundQt instance.

First, create a new file "cs_floss_2.csd", for instance with this code:

sr = 44100
ksmps = 32
0dbfs = 1
nchnls = 1

giSine     ftgen      0, 0, 1024, 10, 1

instr 1
kPitch     expseg     500, p3, 1000
aSine      poscil     .2, kPitch, giSine
           out        aSine
i 1 0 10

Now get the index of these two tabs in executing q.getDocument('cs_floss_1.csd') resp. q.getDocument('cs_floss_2.csd') . This will show something like this:

So in my case the indices are 3 and 4.5  Now you can start, pause and stop any of these files with tasks like these:


If you have checked "Allow simultaneous play" in CsoundQt's Configure->General ...

.. you should be able to run both csds simultaneously. To stop all running files, use:


To set a csd as active, use setDocument(index). This will have the same effect as clicking on the tab. 

Send Score Events

Now comment out the score line in the file "cs_floss_2.csd", or simply remove it. When you now start Csound, this tab should run.6 Now execute this command:

q.sendEvent('i 1 0 2')

This should trigger instrument 1 for two seconds. 

Query File Name or Path

In case you need to know the name7  or the path of a csd file, you have these functions:


Calling the method without any arguments, it refers to the currently active csd. An index as argument links to a specific tab. Here is a Python code snippet which returns indices, file names and file paths of all tabs in CsoundQt:

index = 0
while q.getFileName(index):
    print 'index = %d' % index
    print ' File Name = %s' % q.getFileName(index)
    print ' File Path = %s' % q.getFilePath(index)
    index += 1

Which returns for instance:
index = 0
File Name = /home/jh/Joachim/Stuecke/30Carin/csound/130328.csd
File Path = /home/jh/Joachim/Stuecke/30Carin/csound
index = 1
File Name = /home/jh/src/csoundmanual/examples/transegr.csd
File Path = /home/jh/src/csoundmanual/examples
index = 2
File Name = /home/jh/Arbeitsfläche/test.csd
File Path = /home/jh/Arbeitsfläche
index = 3
File Name = /home/jh/Joachim/Csound/FLOSS/Release03/Chapter_12C_PythonInCsoundQt/cs_floss_1.csd
File Path = /home/jh/Joachim/Csound/FLOSS/Release03/Chapter_12C_PythonInCsoundQt
index = 4
File Name = /home/jh/Joachim/Csound/FLOSS/Release03/Chapter_12C_PythonInCsoundQt/cs_floss_2.csd
File Path = /home/jh/Joachim/Csound/FLOSS/Release03/Chapter_12C_PythonInCsoundQt  

Get and Set csd Text

One of the main features of Python scripting in CsoundQt is the ability to edit any section of a csd file. There are several "get" functions, to query text, and also "set" functions to change or insert text.

Get Text from a csd File

Make sure your "cs_floss_2.csd" is the active tab, and execute the following python code lines:


The q.getOrc() task should return this:

u'\nsr = 44100\nksmps = 32\n0dbfs = 1\nnchnls = 1\n\ngiSine     ftgen      0, 0, 1024, 10, 1\n\ninstr 1\nkPitch     expseg     1000, p3, 500\naSine      poscil     .2, kPitch, giSine\n           out        aSine\nendin\n'

The u'...' indicates that a unicode string is returned. As usual in format expressions, newlines are indicated with the '\n' formatter.

You can also get the text for the <CsOptions>, the text for CsoundQt's widgets and presets, or the full text of this csd:


If you select some text or some widgets, you will get the selection with these commands:


As usual, you can specify any of the loaded csds via its index. So calling q.getOrc(3) instead of q.getOrc()will return the orc text of the csd with index 3, instead of the orc text of the currently active csd.

Set Text in a csd File

Set the cursor anywhere in your active csd, and execute the following line in the Python Console:

q.insertText('my nice insertion')

You will see your nice insertion in the csd file. In case you do not like it, you can choose Edit->Undo. It does not make a difference for the CsoundQt editor whether the text has been typed by hand, or by the internal Python script facility.

Text can also be inserted to individual sections using the functions:


Note that the whole section will be overwritten with the string text.

Opcode Exists

You can ask whether a string is an opcode name, or not, with the function opcodeExtists, for instance:

py> q.opcodeExists('line')
py> q.opcodeExists('OSCsend')
py> q.opcodeExists('Line')
py> q.opcodeExists('Joe')

Example: Score Generation

A typical application for setting text in a csd is to generate a score. There have been numerous tools and programs to do this, and it can be very pleasant to use CsoundQt's Python scripting for this task. Let us modify our previous instrument first to make it more flexible:

EXAMPLE 12C02_score_generated.csd

sr = 44100
ksmps = 32
0dbfs = 1
nchnls = 1

giSine     ftgen      0, 0, 1024, 10, 1

instr 1
iOctStart  =          p4 ;pitch in octave notation at start
iOctEnd    =          p5 ;and end
iDbStart   =          p6 ;dB at start
iDbEnd     =          p7 ;and end
kPitch     expseg     cpsoct(iOctStart), p3, cpsoct(iOctEnd)
kEnv       linseg     iDbStart, p3, iDbEnd
aSine      poscil     ampdb(kEnv), kPitch, giSine
iFad       random     p3/20, p3/5
aOut       linen      aSine, iFad, p3, iFad
           out        aOut
i 1 0 10 ;will be overwritten by the python score generator

The following code will now insert 30 score events in the score section:

from random import uniform
numScoEvents = 30
sco = ''
for ScoEvent in range(numScoEvents):
    start = uniform(0, 40)
    dur = 2**uniform(-5, 3)
    db1, db2 = [uniform(-36, -12) for x in range(2)]
    oct1, oct2 = [uniform(6, 10) for x in range(2)]
    scoLine = 'i 1 %f %f %f %f %d %d\n' % (start, dur, oct1, oct2, db1, db2)
    sco = sco + scoLine

This generates a texture with either falling or rising gliding pitches. The durations are set in a way that shorter durations are more frequently than larger ones. The volume and pitch ranges allow many variations in the simple shape.


Creating a Label

Click on the "Widgets" button to see the widgets panel. Then execute this command in the Python Console:


The properties dialog of the label pops up. Type "Hello Label!" or something like this as text.

When you click "Ok", you will see the label widget in the panel, and a strange unicode string as return value in the Python Console:

The string u'{3a171aa2-4cf8-4f05-9f30-172863909f56}' is a "universally unique identifier" (uuid). Each widget can be accessed by this ID.

Specifying the Common Properties as Arguments

Instead of having a live talk with the properties dialog, we can specify all properties as arguments for the createNewLabel method:

q.createNewLabel(200, 100, "second_label")

This should be the result:

A new label has been created—without opening the properties dialog—at position x=200 y=1008 with the name "second_label". If you want to create a widget not in the active document, but in another tab, you can also specify the tab index. This command will create a widget at the same position and with the same name in the first tab:

q.createNewLabel(200, 100, "second_label", 0)

Setting the Specific Properties

Each widget has a xy position and a channel name.9  But the other properties depend on the type of widget. A Display has name, width and height, but no resolution like a SpinBox. The function setWidgetProperty refers to a widget via its ID and sets a property. Let us try this for a Display widget. This command creates a Display widget with channel name "disp_chan_01" at position x=50 y=150:

q.createNewDisplay(50, 150, "disp_chan_01")

And this sets the text to a new string:10 

q.setWidgetProperty("disp_chan_01", "QCS_label", "Hey Joe!")

The setWidgetProperty method needs the ID of a widget first. This can be expressed either as channel name ("disp_chan_01") as in the command above, or as uuid. As I got the string u'{a71c0c67-3d54-4d4a-88e6-8df40070a7f5}' as uuid, I can also write:

q.setWidgetProperty(u'{a71c0c67-3d54-4d4a-88e6-8df40070a7f5}', "QCS_label", "Hey Joeboe!")

For humans, referring to the channel name as ID is probably preferable ...11  - But as the createNew... method returns the uuid, you can use it implicitely, for instance in this command:

q.setWidgetProperty(q.createNewLabel(70, 70, "WOW"), "QCS_fontsize", 18)

Getting the Property Names and Values

You may have asked how to know that the visible text of a Display widget is called "QCS_label" and the fontsize "QCS_fontsize". If you do not know the name of a property, ask CsoundQt for it via the function listWidgetProperties:
py> q.listWidgetProperties("disp_chan_01")
(u'QCS_x', u'QCS_y', u'QCS_uuid', u'QCS_visible', u'QCS_midichan', u'QCS_midicc', u'QCS_label', u'QCS_alignment', u'QCS_precision', u'QCS_font', u'QCS_fontsize', u'QCS_bgcolor', u'QCS_bgcolormode', u'QCS_color', u'QCS_bordermode', u'QCS_borderradius', u'QCS_borderwidth', u'QCS_width', u'QCS_height', u'QCS_objectName')

As you see, listWidgetProperties returns all properties in a tuple. You can query the value of a single property with the function getWidgetProperty, which takes the uuid and the property as inputs, and returns the property value. So this code snippet asks for all property values of our Display widget:

widgetID = "disp_chan_01"
properties = q.listWidgetProperties(widgetID)
for property in properties:
    propVal = q.getWidgetProperty(widgetID, property)
    print property + ' = ' + str(propVal)

QCS_x = 50
QCS_y = 150
QCS_uuid = {a71c0c67-3d54-4d4a-88e6-8df40070a7f5}
QCS_visible = True
QCS_midichan = 0
QCS_midicc = -3
QCS_label = Hey Joeboe!
QCS_alignment = left
QCS_precision = 3
QCS_font = Arial
QCS_fontsize = 10
QCS_bgcolor = #ffffff
QCS_bgcolormode = False
QCS_color = #000000
QCS_bordermode = border
QCS_borderradius = 1
QCS_borderwidth = 1
QCS_width = 80
QCS_height = 25
QCS_objectName = disp_chan_01

Get the UUIDs of all Widgets 

For getting the uuid strings of all widgets in the active csd tab, type


As always, the uuid strings of other csd tabs can be accessed via the index.

Some Examples for Creating and Modifying Widgets

Create a new slider with the channel name "level" at position 10,10 in the (already open but not necessarily active) document "test.csd":

q.createNewSlider(10, 10, "level", q.getDocument("test.csd"))

Create ten knobs with the channel names "partial_1", "partial_2" etc, and the according labels "amp_part_1", "amp_part_2" etc in the currently active document:

for no in range(10):
        q.createNewKnob(100*no, 5, "partial_"+str(no+1))
        q.createNewLabel(100*no+5, 90, "amp_part_"+str(no+1))
Alternatively, you can store the uuid strings while creating:
knobs, labels = [], []
for no in range(10):
        knobs.append(q.createNewKnob(100*no, 5, "partial_"+str(no+1)))
        labels.append(q.createNewLabel(100*no+5, 90, "amp_part_"+str(no+1)))

The variables knobs and labels now contain the IDs:

py> knobs
[u'{8d10f9e3-70ce-4953-94b5-24cf8d6f6adb}', u'{d1c98b52-a0a1-4f48-9bca-bac55dad0de7}', u'{b7bf4b76-baff-493f-bc1f-43d61c4318ac}', u'{1332208d-e479-4152-85a8-0f4e6e589d9d}', u'{428cc329-df4a-4d04-9cea-9be3e3c2a41c}', u'{1e691299-3e24-46cc-a3b6-85fdd40eac15}', u'{a93c2b27-89a8-41b2-befb-6768cae6f645}', u'{26931ed6-4c28-4819-9b31-4b9e0d9d0a68}', u'{874beb70-b619-4706-a465-12421c6c8a85}', u'{3da687a9-2794-4519-880b-53c2f3b67b1f}']
py> labels
[u'{9715ee01-57d5-407d-b89a-bae2fc6acecf}', u'{71295982-b5e7-4d64-9ac5-b8fbcffbd254}', u'{09e924fa-2a7c-47c6-9e17-e710c94bd2d1}', u'{2e31dbfb-f3c2-43ab-ab6a-f47abb4875a3}', u'{adfe3aef-4499-4c29-b94a-a9543e54e8a3}', u'{b5760819-f750-411d-884c-0bad16d68d09}', u'{c3884e9e-f0d8-4718-8fcb-66e82456f0b5}', u'{c1401878-e7f7-4e71-a097-e92ada42e653}', u'{a7d14879-1601-4789-9877-f636105b552c}', u'{ec5526c4-0fda-4963-8f18-1c7490b0a667}'

Move the first knob 200 pixels downwards:

q.setWidgetProperty( knobs[0], "QCS_y", q.getWidgetProperty(knobs[0], "QCS_y")+200)

Modify the maximum of each knob so that the higher partials have less amplitude range (set maximum to 1, 0.9, 0.8, ..., 0.1):

for knob in range(10):
        q.setWidgetProperty(knobs[knob], "QCS_maximum", 1-knob/10.0)

Deleting widgets

You can delete a widget using the method destroyWidget. You have to pass the widget's ID, again either as channel name or (better) as uuid string. This will remove the first knob in the example above:


This will delete all knobs:

for w in knobs:

And this will delete all widgets of the active document:

for w in q.getWidgetUuids():

Getting and Setting Channel Names and Values

After this cruel act of destruction, let us again create a slider and a display:

py> q.createNewSlider(10, 10, "level")
py> q.createNewDisplay(50, 10, "message")

Now we will ask for the values of these widgets12  with the methods getChannelValue and getChannelString:

py> q.getChannelValue('level')
py> q.getChannelString("level")
py> q.getChannelValue('message')
py> q.getChannelString('message')

As you see, it depends on the type of the widget whether to query its value by getChannelValue or getChannelString. Although CsoundQt will not return an error, it makes no sense to ask a slider for its string (as its value is a number), and a display for its number (as its value is a string).

With the methods setChannelValue and setChannelString we can change the main content of a widget very easily:

py> q.setChannelValue("level", 0.5)
py> q.setChannelString("message", "Hey Joe again!")

This is much more handy than the general method using setWidgetProperty:

py> q.setWidgetProperty("level", "QCS_value", 1)
py> q.setWidgetProperty("message", "QCS_label", "Nono")


Now right-click in the widget panel and choose Store Preset -> New Preset:


You can (but need not) enter a name for the preset. The important thing here is the number of the preset (here 0). - Now change the value of the slider and the text of the display widget. Save again as preset, now being preset 1. - Now execute this:


You will see the content of the widgets reloaded to the first preset. Again, with


you can switch to the second one.

Like all python scripting functions in CsoundQt, you can not only use these methods from the Python Console or the Python Cratch Pad, but also from inside any csd. This is an example how to switch all the widgets to other predefined states, in this case controlled by the score. You will see the widgets for the first three seconds in Preset 0, then for the next three seconds in Preset 1, and finally again in Preset 0:

EXAMPLE 12C03_presets.csd



instr loadPreset
	index = p4
	pycalli "q.loadPreset", index

i "loadPreset" 0 3 0
i "loadPreset" + . 1
i "loadPreset" + . 0
;example by tarmo johannes and joachim heintz 

Csound Functions

Several functions can interact with the Csound engine, for example to query information about it. Note that the functions getSampleRate, getKsmps, getNumChannels and getCurrentCsound refer to a running instance of Csound.

py> q.getVersion() # CsoundQt API version
py> q.getSampleRate()
py> q.getKsmps()
py> q.getNumChannels()
py> q.getCurrentCsound()
CSOUND (C++ object at: 0x2fb5670)

With getCsChannel, getCsStringChannel and setCsChannel you can access csound channels directly, independently from widgets. They are useful when testing a csd for use with the Csound API (in another application, a csLapdsa or Cabbage plugin, Android application) or similar. These are some examples, executed on a running csd instance:

py> q.getCsChannel('my_num_chn')
py> q.getCsStringChannel('my_str_chn')

py> q.setCsChannel('my_num_chn', 1.1)
py> q.setCsChannel('my_str_chn', 'Hey Csound')

py> q.getCsChannel('my_num_chn')
py> q.getCsStringChannel('my_str_chn')
u'Hey Csound'

If you have a function table in your running Csound instance which has for instance been created with the line giSine ftgen 1, 0, 1024, 10, 1, you can query getTableArray like this: 

py> q.getTableArray(1)
MYFLT (C++ object at: 0x35d1c58)

Finally, you can register a Python function as a callback to be executed in between processing blocks for Csound. The first argument should be the text that should be called on every pass. It can include arguments or variables which will be evaluated every time. You can also set a number of periods to skip to avoid.

registerProcessCallback(QString func, int skipPeriods = 0)

You can register the python text to be executed on every Csound control block callback, so you can execute a block of code, or call any function which is already defined.

Creating Own GUIs with PythonQt

One of the very powerful features of using Python inside CsoundQt is the ability to build own GUIs. This is done via the PythonQt library which gives you access to the Qt toolkit via Python. We will show some examples here. Have a look in the "Scripts" menu in CsoundQt to find much more (you will find the code in the "Editor" submenu).

Dialog Box

Sometimes it is practical to ask from user just one question - number or name of something and then execute the rest of the code (it can be done also inside a csd with python opcodes). In Qt, the class to create a dialog for one question is called QInputDialog.

To use this or any other Qt classes, it is necessary to import the PythonQt and its Qt submodules. In most cases it is enough to add this line:

from PythonQt.Qt import *


from PythonQt.QtGui import *

At first an object of QInputDialog must be defined, then you can use its methods getInt, getDouble, getItem or getText to read the input in the form you need. This is a basic example:

from PythonQt.Qt import *

inpdia = QInputDialog()
myInt = inpdia.getInt(inpdia,"Example 1","How many?")
print myInt
# example by tarmo johannes

Note that the variable myInt is now set to a value which remains in your Python interpreter. Your Python Console may look like this when executing the code above, and then ask for the value of myInt:

Evaluated 5 lines.
py> myInt

Depending on the value of myInt, you can do funny or serious things. This code re-creates the Dialog Box whenever the user enters the number 1:

from PythonQt.Qt import *

def again():
    inpdia = QInputDialog()
    myInt = inpdia.getInt(inpdia,"Example 1","How many?")
    if myInt == 1:
        print "If you continue to enter '1' I will come back again and again."
        print "Thanks - Leaving now."
# example by joachim heintz

This is a simple example showing how you can embed an own GUI in your Csound code. Here, Csound waits for the user input, and the prints out the entered value as the Csound variable giNumber:

    EXAMPLE 12C04_dialog.csd


pyruni {{
from PythonQt.Qt import *
dia = QInputDialog()

giNumber pyevali {{
dia.getDouble(dia,"CS question","Enter number: ")
}} ; get the number from Qt dialog

instr 1
	print giNumber

i 1 0 0
;example by tarmo johannes

Simple GUI with Buttons

The next example takes the user input (as a string) and transforms it to a sounding sequence of notes. First, make sure that the following csd is your active tab in CsoundQt:

    EXAMPLE 12C05_string_sound.csd


sr = 44100
nchnls = 2
0dbfs = 1
ksmps = 32

giSine ftgen 1, 0, 4096, 10, 1 ; sine

	Sstr strget p4
	ilen strlen Sstr
	ipos = 0
marker:   ; convert every character in the string to pitch
    ichr strchar Sstr, ipos
    icps = cpsmidinn(ichr)-$INSTNO*8
    ;print icps
    event_i "i", "sound", 0+ipos/8, p3, ichr,icps, $INSTNO ; chord with arpeggio
    loop_lt ipos, 1, ilen, marker

instr 1

instr 2

instr 3

instr sound
	ichar = p4
	ifreq = p5
	itype = p6
	kenv linen 0.1,0.1, p3,0.5	
	if itype== 1 then
		asig pluck kenv,ifreq,ifreq,0, 3, 0
	elseif itype==2 then
		kenv adsr 0.05,0.1,0.5,1
		asig poscil kenv*0.1,ifreq,giSine
		asig	buzz kenv,ifreq,10, giSine
	outs asig,asig

f0 3600
i 1 0 4 "huhuu"
;example by tarmo johannes

Now copy this Python code into your Python Scratch Pad and evaluate it. Then type anything in the "type here" box and push the "insert" button. After pushing "play", the string will be played. You can also send the string as real-time event, to different instruments, in different durations.

from PythonQt.Qt import *

# FUNCTIONS==============================

def insert(): # read input from UI and insert a line to score of csd file, open in CsoundQt with index csdIndex
    scoreLine = "f0 3600\n" + "i " + instrSpinBox.text + " 0 " + durSpinBox.text + ' "' + par1LineEdit.text + "\""
    print scoreLine
    q.setSco(scoreLine, csdIndex)
def play(): # play file with index csdIndex
    print "PLAY"

def send(): # read input from UI send live event
    scoreLine = "i " + instrSpinBox.text + " 0 " + durSpinBox.text + ' "' + par1LineEdit.text + "\""
    print scoreLine
    q.sendEvent(csdIndex, scoreLine)

def stopAndClose(): #stop csdIndex, close UI
    print "STOP"

# MAIN ====================================

window = QWidget() # window as main widget
layout = QGridLayout(window) # use gridLayout - the most flexible one - to place the widgets in a table-like structure
window.setWindowTitle("PythonQt inteface example")

instrLabel = QLabel("Select instrument")
layout.addWidget(instrLabel,0,0) # first row, first column

instrSpinBox = QSpinBox(window)
layout.addWidget(instrSpinBox, 0, 1) # first row, second column

durLabel = QLabel("Duration: ")
layout.addWidget(durLabel,1,0)  # etc

durSpinBox = QSpinBox(window)
layout.addWidget(durSpinBox, 1, 1)

par1Label = QLabel("Enter string for parameter 1: ")

par1LineEdit = QLineEdit(window)
par1LineEdit.setMaxLength(30) # don't allow too long strings
par1LineEdit.setText("type here")

insertButton = QPushButton("Insert",window)
layout.addWidget(insertButton, 3,0)

playButton = QPushButton("Play",window)
layout.addWidget(playButton, 3,1)

sendButton = QPushButton("Send event",window)
layout.addWidget(sendButton, 4,0)

closeButton = QPushButton("Close",window)
layout.addWidget(closeButton, 4,1)

# connect buttons and functions  ================
#NB! function names must be  without parenthesis!
# number and type of arguments of the signal and slot (called function) must match

insertButton.connect(SIGNAL("clicked()"),insert ) # when clicked, run function insert()
playButton.connect(SIGNAL("clicked()"),play)  #etc

window.show() # show the window and wait for clicks on buttons

A Color Controller

To illustrate how to use power of Qt together with CsoundQt, the following example uses the color picking dialog of Qt. When user moves the cursor around in the RGB palette frame, the current red-green-blue values are forwarded to CsoundQt as floats in 0..1, visualized as colored meters and used as controlling parameters for sound.

Qt's object QColorDialog emits the signal currentColorChanged(QColor) every time when any of the RGB values in the colorbox has changed. The script connects the signal to a function that forwards the color values to Csound. So with one mouse movement, three parameters can be controlled instantly.

In the Csound implementation of this example I used - thinking on the colors - three instruments from Richard Boulanger's "Trapped in convert" - red, green and blue. The RGB values of the dialog box control the mix between these three instruments.

As usual, let the following csd be your active tab in CsoundQt, then run the Python code in the Python Scratch Pad.13 

    EXAMPLE 12C06_color_controller.csd

sr = 44100
ksmps = 32
nchnls = 2

garvb  init     0
alwayson "_reverb"

;==================================== RED ===================================;
; parameters from original score
;i 8   15.5   3.1     3      50       4000   129    8      2.6    0.3
       instr   red
ifuncl =       16

p4 = 2.2 ; amp
p5 = 50 ; FilterSweep StartFreq
p6 = 4000 ; FilterSweep EndFreq
p7= 129 ; bandwidth
p8 = 8 ; cps of rand1
p9 = 2.6 ; cps of rand2
p10 = 0.3 ; reverb send factor

k1     expon   p5, p3, p6
k2     line    p8, p3, p8 * .93
k3     phasor  k2
k4     table   k3 * ifuncl, 20
anoise rand    8000
aflt1  reson   anoise, k1, 20 + (k4 * k1 / p7), 1

k5     linseg  p6 * .9, p3 * .8, p5 * 1.4, p3 * .2, p5 * 1.4
k6     expon   p9 * .97, p3, p9
k7     phasor  k6
k8     tablei  k7 * ifuncl, 21
aflt2  reson   anoise, k5, 30 + (k8 * k5 / p7 * .9), 1

abal   oscil   1000, 1000, 1
a3     balance aflt1, abal
a5     balance aflt2, abal

k11    linen   p4, .15, p3, .5
a3     =       a3 * k11
a5     =       a5 * k11

k9     randh   1, k2
aleft  =       ((a3 * k9) * .7) + ((a5 * k9) * .3)
k10    randh   1, k6
aright =       ((a3 * k10) * .3)+((a5 * k10) * .7)
klevel invalue "red"
klevel port klevel,0.05	
       outs    aleft*klevel, aright*klevel
garvb  =       garvb + (a3 * p10)*klevel

;==================================== BLUE ==================================;
;i 2   80.7   8       0      8.077    830    0.7    24     19     0.13
       instr blue                               ; p6 = amp

p5 = 8.077 ; pitch
p6 = 830 ; amp
p7 = 0.7 ; reverb send factor
p8 = 24 ; lfo freq
p9 = 19 ; number of harmonic
p10 = 0.1+rnd(0.2) ;0.5 ; sweep rate

ifreq  random 500,1000;cpspch(p5)
k1     randi    1, 30
k2     linseg   0, p3 * .5, 1, p3 * .5, 0
k3     linseg   .005, p3 * .71, .015, p3 * .29, .01
k4     oscil    k2, p8, 1,.2
k5     =        k4 + 2

ksweep linseg   p9, p3 * p10, 1, p3 * (p3 - (p3 * p10)), 1

kenv   expseg   .001, p3 * .01, p6, p3 * .99, .001
asig   gbuzz    kenv, ifreq + k3, k5, ksweep, k1, 15

klevel invalue "blue"
klevel port klevel,0.05	
asig = asig*klevel
       outs     asig, asig
garvb  =        garvb + (asig * p7)

;==================================== GREEN =================================;
; i 5   43     1.1     9.6    3.106    2500   0.4    1.0    8      3    17  34

        instr  green                             ; p6 = amp
p5 = 3.106 ; pitch
p6 = 2500 ; amp
p7 = 0.4 ; reverb send
p8 = 0.5 ; pan direction
p9 = 8 ; carrier freq
p10 = 3 ; modulator freq
p11 = 17 ; modulation index
p12 = 34 ; rand freq

ifreq   =      cpspch(p5)                    ; p7 = reverb send factor
                                             ; p8 = pan direction
k1     line    p9, p3, 1                     ; ... (1.0 = L -> R, 0.1 = R -> L)
k2     line    1, p3, p10                    ; p9 = carrier freq
k4     expon   2, p3, p12                    ; p10 = modulator freq
k5     linseg  0, p3 * .8, 8, p3 * .2, 8     ; p11 = modulation index
k7     randh   p11, k4                       ; p12 = rand freq
k6     oscil   k4, k5, 1, .3

kenv1  linen   p6, .03, p3, .2
a1     foscil  kenv1, ifreq + k6, k1, k2, k7, 1

kenv2  linen   p6, .1, p3, .1
a2     oscil   kenv2, ifreq * 1.001, 1

amix   =       a1 + a2
kpan   linseg  int(p8), p3 * .7, frac(p8), p3 * .3, int(p8)
klevel invalue "green"
klevel port klevel,0.05
amix = amix*klevel
       outs    amix * kpan, amix * (1 - kpan)
garvb  =       garvb + (amix * p7)

 instr   _reverb
p4 = 1/10                          ; p4 = panrate
k1     oscil   .5, p4, 1
k2     =       .5 + k1
k3     =       1 - k2	
asig   reverb  garvb, 2.1
       outs    asig * k2, (asig * k3) * (-1)
garvb  =       0

;========================= FUNCTIONS ========================================;
f1   0  8192  10   1
; 15 - vaja
f15  0  8192  9    1   1   90
;kasutusel red
f16  0  2048  9    1   3   0   3   1   0   6   1   0
f20  0  16   -2    0   30  40  45  50  40  30  20  10  5  4  3  2  1  0  0  0
f21  0  16   -2    0   20  15  10  9   8   7   6   5   4  3  2  1  0  0

i "red" 0 20
i "green" 0 20
i "blue" 0 6
i . + 3
i . + 4
i . + 7

f 0 1800

;example by tarmo johannes, after richard boulanger
from PythonQt.Qt import *

# write the current RGB values as floats 0..1 to according channels of "rgb-widgets.csd"
def getColors(currentColor):

# main-----------
cdia = QColorDialog() #create QColorDiaog object
cdia.connect(SIGNAL("currentColorChanged(QColor)"),getColors) # create connection between  color changes in the dialog window and function getColors
cdia.show() # show the dialog window,
q.play(csd) # and play the csd

List of PyQcsObject Methods in CsoundQt

Load/Create/Activate a csd File

int loadDocument(QString name, bool runNow = false)
int getDocument(QString name = "")
int newDocument(QString name)
void setDocument(int index) 

Play/Pause/Stop a csd File

void play(int index = -1, bool realtime = true)
void pause(int index = -1)
void stop(int index = -1)
void stopAll() 

Send Score Events

void sendEvent(int index, QString events)
void sendEvent(QString events)
void schedule(QVariant time, QVariant event) 

Query File Name/Path

QString getFileName(int index = -1)
QString getFilePath(int index = -1) 

Get csd Text

QString getSelectedText(int index = -1, int section = -1)
QString getCsd(int index = -1)
QString getFullText(int index = -1)
QString getOrc(int index = -1)
QString getSco(int index = -1)
QString getWidgetsText(int index = -1)
QString getSelectedWidgetsText(int index = -1)
QString getPresetsText(int index = -1)
QString getOptionsText(int index = -1) 

Set csd Text

void insertText(QString text, int index = -1, int section = -1)
void setCsd(QString text, int index = -1)
void setFullText(QString text, int index = -1)
void setOrc(QString text, int index = -1)
void setSco(QString text, int index = -1)
void setWidgetsText(QString text, int index = -1)
void setPresetsText(QString text, int index = -1)
void setOptionsText(QString text, int index = -1) 

Opcode Exists

bool opcodeExists(QString opcodeName) 

Create Widgets

QString createNewLabel(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewDisplay(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewScrollNumber(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewLineEdit(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewSpinBox(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewSlider(QString channel, int index = -1)
QString createNewSlider(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewButton(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewKnob(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewCheckBox(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewMenu(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewMeter(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewConsole(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewGraph(int x = 0, int y = 0, QString channel = QString(), int index = -1)
QString createNewScope(int x = 0, int y = 0, QString channel = QString(), int index = -1)

Query Widgets

QVariant getWidgetProperty(QString widgetid, QString property, int index= -1)
double getChannelValue(QString channel, int index = -1)
QString getChannelString(QString channel, int index = -1)
QStringList listWidgetProperties(QString widgetid, int index = -1)
QStringList getWidgetUuids(int index = -1) 

Modify Widgets

void setWidgetProperty(QString widgetid, QString property, QVariant value, int index= -1)
void setChannelValue(QString channel, double value, int index = -1)
void setChannelString(QString channel, QString value, int index = -1) 

Delete Widgets

bool destroyWidget(QString widgetid) 


void loadPreset(int presetIndex, int index = -1) 

Live Event Sheet

QuteSheet* getSheet(int index = -1, int sheetIndex = -1)
QuteSheet* getSheet(int index, QString sheetName) 

Csound / API

QString getVersion()
void refresh()
void setCsChannel(QString channel, double value, int index = -1)
void setCsChannel(QString channel, QString value, int index = -1)
double getCsChannel(QString channel, int index = -1)
QString getCsStringChannel(QString channel, int index = -1)
CSOUND* getCurrentCsound()
double getSampleRate(int index = -1)
int getKsmps(int index = -1)
int getNumChannels(int index = -1)
MYFLT *getTableArray(int ftable, int index = -1)
void registerProcessCallback(QString func, int skipPeriods = 0, int index = -1) 


  1. This chapter is based on Andrés Cabrera's paper Python Scripting in QuteCsound at the Csound Conference in Hannover (2011).^
  2. This should be the case for CsoundQt 0.7 or higher on OSX. On Windows, the corrent version 0.7.0 is built with PythonQt support. You must have installed Python 2.7, too. For building CsoundQt with Python support, have a look at the descriptions in http://sourceforge.net/apps/mediawiki/qutecsound.^
  3. See chapter 12B for more information on these.^
  4. To evaluate multiple lines of Python code in the Scratch Pad, choose either Edit->Evaluate Section (Alt+E), or select and choose Edit->Evaluate Selection (Alt+Shift+E).^
  5. If you have less or more csd tabs already while creating the new files, the index will be lower or higher.^
  6. If not, you are probably using an older version of Csound. In this case, insert the scoreline "f 0 99999", and this csd will run and wait for your real-time score events for 99999 seconds.^
  7. Different to most usages, 'name' means here the full path including the file name.^
  8. Pixels from left resp. from top.^
  9. Only a label does not have a channel name. So as we saw, in case of a label the name is its displayed text.^
  10. For the main property of a widget (text for a Display, number for Sliders, SpinBoxes etc) you can also use the setChannelString and setChannelValue method. See below at "Getting and Setting Channel Values" ^
  11. Note that two widgets can share the same channel name (for instance a slider and a spinbox). In this case, referring to a widget via its channel name is not possible at all.^
  12. Here again accessed by the channel name. Of course accessing by uuid would also be possible (and more safe, as explained above).^
  13. The example should also be availiable in CsoundQt's Scripts menu.^

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