tdemultimedia/doc/artsbuilder/artsbuilder.docbook

<chapter id="artsbuilder">
<title>&arts-builder;</title>

<sect1 id="overview">
<title>Overview</title>

<para>
First of all, when trying to run &arts-builder; , you should also be
running the sound server (&artsd;). Usually, when you use &kde; 2.1,
this should already be the case. If not, you can configure the automatic
sound server startup in &kcontrol; under
<menuchoice><guilabel>Sound</guilabel><guilabel>Sound
Server</guilabel></menuchoice>.
</para>

<para>
When you are running &arts;, it always runs small modules. &arts-builder;
is a tool to create new structures of small connected modules. You
simply click the modules inside the grid. To do so, choose them from the
<guimenu>Modules</guimenu> menu, and then click somewhere in the
green-gray plane.
</para>

<para>
Modules usually have ports (where usually audio signals are flowing in
or out). To connect two ports, click on the first, which causes it to
turn orange, and then click on the second. You can only connect an input
port (on the upper side of a module) with an output port (on the lower
side of a module). If you want to assign a fixed value to a port (or
disconnect it), do so by double clicking on the port.
</para>

</sect1>

<sect1 id="artsbuilder-tutorial">
<title>Tutorial</title>

<sect2 id="step-1">
<title>Step 1</title>

<para>
Start &arts-builder;.
</para>

<para>
You need a Synth&lowbar;AMAN&lowbar;PLAY-module to hear the output you
are creating. So create a Synth&lowbar;AMAN&lowbar;PLAY-module by
selecting <menuchoice><guimenu>Modules</guimenu>
<guisubmenu>Synthesis</guisubmenu> <guisubmenu>SoundIO</guisubmenu>
<guisubmenu>Synth&lowbar;AMAN&lowbar;PLAY</guisubmenu></menuchoice> and
clicking on the empty module space. Put it below the fifth line or so,
because we'll add some stuff above.
</para>

<para>
The module will have a parameter <parameter>title</parameter> (leftmost
port), and <parameter>autoRestoreID</parameter> (besides the leftmost
port) for finding it. To fill these out, doubleclick on these ports,
select constant value and type <userinput>tutorial</userinput> in the
edit box. Click <guibutton>OK</guibutton> to apply.
</para>

<para>
Select <menuchoice><guimenu>File</guimenu><guimenuitem>Execute
structure</guimenuitem> </menuchoice>. You will hear absolutely
nothing. The play module needs some input yet... ;) If you have listened
to the silence for a while, click <guibutton>OK</guibutton> and go to
Step 2
</para>
</sect2>

<sect2 id="step-2">
<title>Step 2</title>

<para>Create a Synth&lowbar;WAVE&lowbar;SIN module (from <menuchoice>
<guimenu>Modules</guimenu> <guimenuitem>Synthesis</guimenuitem>
<guimenuitem>Waveforms</guimenuitem></menuchoice>) 
and put it above the Synth&lowbar;AMAN&lowbar;PLAY module. (Leave one line
space in between).
</para>

<para>
As you see, it produces some output, but requires a
<guilabel>pos</guilabel> as input. First lets put the output to the
speakers. Click on the <guilabel>out</guilabel> port of the
Synth&lowbar;WAVE&lowbar;SIN and then on the <guilabel>left</guilabel>
port of Synth&lowbar;AMAN&lowbar;PLAY. Voila, you have connected two
modules.
</para>

<para>
All oscillators in &arts; don't require a frequency as input, but a
position in the wave. The position should be between 0 and 1, which maps
for a standard Synth&lowbar;WAVE&lowbar;SIN object to the range
0..2*pi. To generate oscillating values from a frequency, a
Synth&lowbar;FREQUENCY modules is used.
</para>

<para>
Create a Synth&lowbar;FREQUENCY module (from <menuchoice>
<guimenu>Modules</guimenu> <guimenu>Synthesis</guimenu>
<guimenu>Oscillation &amp; Modulation</guimenu> </menuchoice>) and
connect it's <quote>pos</quote> output to the <quote>pos</quote> input
of your Synth&lowbar;WAVE&lowbar;SIN. Specify the frequency port of the
FREQUENCY generator as constant value 440.
</para>


<para>
Select <menuchoice><guimenu>File</guimenu><guimenuitem>Execute
structure</guimenuitem></menuchoice>. You will hear a sinus wave at 440
Hz on one of your speakers. If you have listened to it for a while,
click <guibutton>OK</guibutton> and go to Step 3.
</para>

</sect2>

<sect2 id="step-3">
<title>Step 3</title>

<para>
Ok, it would be nicer if you would hear the sin wave on both speakers.
Connect the right port of Synth&lowbar;PLAY to the outvalue of the
Synth&lowbar;WAVE&lowbar;SIN as well.
</para>

<para>Create a Synth&lowbar;SEQUENCE object (from
<menuchoice><guimenu>Modules</guimenu>
<guisubmenu>Synthesis</guisubmenu><guisubmenu>Midi &amp;
Sequencing</guisubmenu></menuchoice>). It should be at the top of the
screen. If you need more room you can move the other modules by
selecting them (to select multiple modules use &Shift;), and dragging
them around.
</para>

<para>
Now connect the frequency output of Synth&lowbar;SEQUENCE to the
frequency input of the Synth&lowbar;FREQUENCY module. Then specify the
sequence speed as constant value 0.13 (the speed is the leftmost port).
</para>

<para>
Now go to the rightmost port (sequence) of Synth&lowbar;SEQUENCE and
type in as constant value <userinput>A-3;C-4;E-4;C-4;</userinput> this
specifies a sequence. More to that in the Module Reference.
</para>

<note>
<para>Synth&lowbar;SEQUENCE really <emphasis>needs</emphasis> a sequence
and the speed. Without that you'll perhaps get core dumps.
</para>
</note>

<para>
Select <menuchoice><guimenu>File</guimenu><guimenuitem>Execute
Structure</guimenuitem></menuchoice>.  You will hear a nice sequence
playing.  If you have enjoyed the feeling, click
<guibutton>OK</guibutton> and go to Step 4.
</para>
</sect2>

<sect2 id="step-4">
<title>Step 4</title>

<para>Create a Synth&lowbar;PSCALE module (from
<menuchoice><guimenu>Modules</guimenu>
<guisubmenu>Synthesis</guisubmenu> <guisubmenu>Envelopes</guisubmenu>
</menuchoice>). Disconnect the outvalue of the SIN wave by doubleclicking it
and choosing <guilabel>not connected</guilabel>. Connect
</para>

<orderedlist><listitem>
<para>The SIN outvalue to the PSCALE invalue</para>
</listitem>
<listitem>
<para>The PSCALE outvalue to the AMAN_PLAY left</para>
</listitem>
<listitem>
<para>The PSCALE outvalue to the AMAN_PLAY right</para>
</listitem>
<listitem>
<para>The SEQUENCE pos to the PSCALE pos</para>
</listitem>
</orderedlist>

<para>
Finally, set the PSCALE top to some value, for instance 0.1.
</para>

<para>
How that works now: The Synth&lowbar;SEQUENCE gives additional
information about the position of the note it is playing right now,
while 0 means just started and 1 means finished. The Synth&lowbar;PSCALE
module will scale the audio stream that is directed through it from a
volume 0 (silent) to 1 (original loudness) back to 0 (silent). According
to the position. The position where the peak should occur can be given
as pos. 0.1 means that after 10&percnt; of the note has been played, the
volume has reached its maximum, and starts decaying afterwards.
</para>


<para>Select <menuchoice><guimenu>File</guimenu><guimenuitem>Execute
Structure</guimenuitem></menuchoice>.  You will hear a nice sequence
playing.  If you have enjoyed the feeling, click
<guibutton>OK</guibutton> and go to Step 5.
</para>

</sect2>

<sect2 id="step-5-starting-to-beam-data-around">
<title>Step 5: Starting to beam data around ;)</title>

<para>Start another &arts-builder;</para>

<para>
Put a Synth&lowbar;AMAN&lowbar;PLAY into it, configure it to a sane
name. Put a Synth&lowbar;BUS&lowbar;DOWNLINK into it and:</para>

<orderedlist>
<listitem>
<para>
Set Synth&lowbar;BUS&lowbar;DOWNLINK bus to audio (that is just a name,
call it fred if you like)
</para>
</listitem>
<listitem>
<para>
Connect Synth&lowbar;BUS&lowbar;DOWNLINK left to
Synth&lowbar;AMAN&lowbar;PLAY left
</para>
</listitem>
<listitem>
<para>
Connect Synth&lowbar;BUS&lowbar;DOWNLINK right to
Synth&lowbar;AMAN&lowbar;PLAY right
</para>
</listitem>
</orderedlist>

<para>
Start executing the structure. As expected, you hear nothing, ... not
yet.
</para>

<para>
Go back to the structure with the Synth&lowbar;WAVE&lowbar;SIN stuff and
replace the Synth&lowbar;AMAN&lowbar;PLAY module by an
Synth&lowbar;BUS&lowbar;UPLINK, and configure the name to audio (or fred
if you like). Deleting modules works with selecting them and choosing
<menuchoice><guimenu>Edit</guimenu>
<guimenuitem>delete</guimenuitem></menuchoice> from the menu (or
pressing the <keycap>Del</keycap> key).
</para>

<para>
Hit <menuchoice><guimenu>File</guimenu> <guilabel>Execute
structure</guilabel></menuchoice>. You will hear the sequence with
scaled notes, transported over the bus.
</para>

<para>
If you want to find out why something like this can actually be useful,
click <guibutton>OK</guibutton> (in the &arts-builder; that is executing
the Synth&lowbar;SEQUENCE stuff, you can leave the other one running)
and go to Step 6.
</para>
</sect2>

<sect2 id="step-6-beaming-for-advanced-users">
<title>Step 6: Beaming for advanced users</title>

<para>
Choose <menuchoice><guimenu>File</guimenu><guimenuitem>Rename</guimenuitem>
</menuchoice> structure from the menu of the artsbuilder which
contains the Synth&lowbar;SEQUENCE stuff, and call it tutorial. Hit
<guibutton>OK</guibutton>.
</para>

<para>
Choose <menuchoice><guimenu>File</guimenu> <guimenuitem>Save</guimenuitem>
</menuchoice>
</para>

<para>
Start yet another &arts-builder; and choose
<menuchoice><guimenu>File</guimenu><guimenuitem>Load</guimenuitem>
</menuchoice>, and load the tutorial again.
</para>

<para>
Now you can select
<menuchoice><guimenu>File</guimenu><guimenuitem>Execute
structure</guimenuitem> </menuchoice>in both &arts-builder;s having that
structure. You'll now hear two times the same thing. Depending on the
time when you start it it will sound more or less nice.
</para>

<para>
Another thing that is good to do at this point in time is: start
&noatun;, and play some <literal role="extension">mp3</literal>. Start
&artscontrol;. Go to
<menuchoice><guimenu>View</guimenu><guimenuitem>View audio
manager</guimenuitem></menuchoice>. What you will see is &noatun; and
your <quote>tutorial</quote> playback structure playing something. The
nice thing you can do is this: doubleclick on &noatun;. You'll now get a
list of available busses. And see? You can assign &noatun; to send it's
output via the audio bus your tutorial playback structure provides.
</para>
</sect2>

<sect2 id="step-7-midi-synthesis">
<title>Step 7: Midi synthesis</title>

<para>
Finally, now you should be able to turn your sin wave into an real
instrument. This only makes sense if you have something handy that could
send &MIDI; events to &arts;. I'll describe here how you can use some
external keyboard, but a midibus aware sequence like &brahms; will work
as well.
</para>

<para>
First of all, clean up on your desktop until you only have one
&arts-builder; with the sine wave structure running (not executing).
Then, three times go to <menuchoice><guimenu>Ports</guimenu>
<guisubmenu>Create IN audio signal</guisubmenu></menuchoice>, and three
times to <menuchoice><guimenu>Ports</guimenu> <guisubmenu>Create OUT
audio signal</guisubmenu></menuchoice>. Place the ports somewhere.
</para>

<para>
Finally, go to <menuchoice><guimenu>Ports</guimenu> <guilabel>Change
positions and names</guilabel></menuchoice> and call the ports
frequency, velocity, pressed, left, right, done.
</para>

<para>
Finally, you can delete the Synth&lowbar;SEQUENCE module, and rather
connect connect the frequency input port of the structure to the
Synth&lowbar;FREQUENCY frequency port. Hm. But what do do about
pos?</para> <para>We don't have this, because with no algorithm in the
world, you can predict when the user will release the note they just
pressed on the midi keyboard. So we rather have a pressed parameter
instead that just indicates wether the user still holds down the
key. (pressed = 1: key still hold down, pressed = 0: key
released)
</para>

<para>
That means the Synth&lowbar;PSCALE object also must be replaced
now. Plug in a Synth&lowbar;ENVELOPE&lowbar;ADSR instead (from
<menuchoice><guimenu>Modules</guimenu>
<guisubmenu>Synthesis</guisubmenu> <guisubmenu>Envelopes</guisubmenu>
</menuchoice>).  Connect:
</para>

<orderedlist>
<listitem>
<para>The pressed structure input to the ADSR active</para>
</listitem>
<listitem>
<para>The SIN outvalue to the ADSR invalue</para>
</listitem>
<listitem>
<para>The ADSR outvalue to the left structure output</para>
</listitem><listitem>
<para>The ADSR outvalue to the right structure output</para>
</listitem>
</orderedlist>

<para>
Set the parameters attack to 0.1, decay to 0.2, sustain to 0.7, release
to 0.1.
</para>

<para>
Another thing we need to think of is that the instrument structure
somehow should know when it is ready playing and then be cleaned up,
because otherwise it would be never stopped even if the note has been
released. Fortunately, the ADSR envelope knows when the will be nothing
to hear anymore, since it anyway scales the signal to zero at some point
after the note has been released.
</para>

<para>
This is indicated by setting the done output to 1. So connect this to
the done output of the structure. The structure will be removed as soon
as done goes up to 1.
</para>

<para>
Rename your structure to instrument_tutorial (from <menuchoice><guimenu>
File</guimenu> <guimenuitem>Rename
structure</guimenuitem></menuchoice>. Then, save it using save as (the
default name offered should be instrument_tutorial
now).</para><para>Start artscontrol, and go to
<menuchoice><guimenu>View</guimenu><guimenuitem>Midi
Manager</guimenuitem></menuchoice>, and choose
<menuchoice><guimenu>Add</guimenu><guimenuitem>aRts Synthesis Midi
Output</guimenuitem></menuchoice>.  Finally, you should be able to
select your instrument (tutorial) here.
</para>

<para>
Open a terminal and type
<userinput><command>midisend</command></userinput>. You'll see that
<command>midisend</command> and the instrument are listed now in the
&arts; &MIDI; manager.  After selecting both and hitting
<guibutton>connect</guibutton>, we're finally done. Take your keyboard
and start playing (of course it should be connected to your computer).
</para>
</sect2>

<sect2 id="suggestions">
<title>Suggestions</title>

<para>
You now should be able to work with &arts;. Here are a few tips what you
could try to improve with your structures now:
</para>

<itemizedlist>
<listitem>
<para>
Try using other things than a SIN wave. When you plug in a TRI wave, you
will most likely think the sound is not too nice. But try appending a
SHELVE&lowbar;CUTOFF filter right after the TRI wave to cut the
frequenciesabove a certain frequency (try something like 1000 Hz, or
even better two times the input frequency or input frequency+200Hz or
something like that).
</para>
</listitem>
<listitem>
<para>
Try using more than one oscillator. Synth&lowbar;XFADE can be used to
cross fade (mix) two signals, Synth&lowbar;ADD to add them.
</para>
</listitem>
<listitem>
<para>
Try setting the frequencies of the oscillators to not exactly the same
value, that gives nice oscillations.
</para>
</listitem>
<listitem>
<para>
Experiment with more than one envelope.
</para>
</listitem>
<listitem>
<para>
Try synthesizing instruments with different output left and right.
</para>
</listitem>
<listitem>
<para>
Try postprocessing the signal after it comes out the bus downlink.  You
could for instance mix a delayed version of the signal to the original
to get an echo effect.
</para>
</listitem>
<listitem>
<para>
Try using the velocity setting (its the strength with which the note has
been pressed, you could also say volume). The special effect is always
when this not only modifies the volume of the resulting signal, but as
well the sound of the instrument (for instance the cutoff frequency).
</para>
</listitem>
<listitem>
<para>...</para>
</listitem>
</itemizedlist>

<para>
If you have created something great, please consider providing it for
the &arts; web page. Or for inclusion into the next release.
</para>
</sect2>

</sect1>

<sect1 id="artsbuilder-examples">
<title>Examples</title>

<para>
&arts-builder; comes with several examples, which can be opened through
<menuchoice><guimenu>File</guimenu><guimenuitem>Open
Example...</guimenuitem> </menuchoice>. Some of them are in the
folder, some of them (which for some reason don't work with the
current release) are left in the todo folder.
</para>
<para>
The examples fall into several categories:
</para>

<itemizedlist>
<listitem>
<para>
Standalone examples illustrating how to use each of the built-in
arts modules (named <filename>example_*.arts</filename>). These
typically send some output to a sound card.
</para>
</listitem>

<listitem>
<para>
Instruments built from lower level arts modules (named
<filename>instrument_*.arts</filename>). These following a standard
convention for input and output ports so they can be used by the &MIDI;
manager in &artscontrol;.
</para>
</listitem>

<listitem>
<para>
Templates for creating new modules (names
<filename>template_*.arts</filename>).
</para>
</listitem>

<listitem>
<para>
Effects which can be used as reusable building blocks (named
<filename>effect_*.arts</filename>) [ all in todo ]
</para>
</listitem>

<listitem>
<para>
Mixer elements used for creating mixers, including graphical
controls (named <filename>mixer_element_*.arts</filename>). [ all in todo ]
</para>
</listitem>

<listitem>
<para>
Miscellaneous modules that don't fit into any of the above categories.
</para>
</listitem>
</itemizedlist>

<variablelist>
<title>Detailed Description Of Each Module:</title>
<varlistentry>
<term><filename>example_stereo_beep.arts</filename></term>
<listitem>
<para>
Generates a 440Hz sine wave tone in the left channel and an 880Hz sine
wave tone in the right channel, and sends it to the sound card
output. This is referenced in the &arts; documentation.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_sine.arts</filename></term>
<listitem>
<para>
Generates a 440 Hz sine wave.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_pulse.arts</filename></term>
<listitem>
<para>
Generates a 440 Hz pulse wave with a 20% duty cycle.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_softsaw.arts</filename></term>
<listitem>
<para>
Generates a 440 Hz sawtooth wave.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_square.arts</filename></term>
<listitem>
<para>
Generates a 440 Hz square wave.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_tri.arts</filename></term>
<listitem>
<para>
Generates a 440 Hz triangle wave.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_noise.arts</filename></term>
<listitem>
<para>
Generates white noise.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_dtmf1.arts</filename></term>
<listitem>
<para>
Generates a dual tone by producing 697 and 1209 Hz sine waves, scaling
them by 0.5, and adding them together. This is the DTMF tone for the
digit "1" on a telephone keypad.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_atan_saturate.arts</filename></term>
<listitem>
<para>
Runs a triangle wave through the atan saturate filter.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_autopanner.arts</filename></term>
<listitem>
<para>
Uses an autopanner to pan a 400 Hz sine wave between the left and right
speakers at a 2 Hz rate.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_brickwall.arts</filename></term>
<listitem>
<para>
Scales a sine wave by a factor of 5 and then runs it through a brickwall
limiter.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_bus.arts</filename></term>
<listitem>
<para>
Downlinks from a bus called <quote>Bus</quote> and uplinks to the bus
<quote>out_soundcard</quote> with the left and right channels reversed.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_cdelay.arts</filename></term>
<listitem>
<para>
Downlinks from a bus called <quote>Delay</quote>, uplinks the right
channel through a 0.5 second cdelay, and the left channel unchanged. You
can use &artscontrol; to connect the effect to a sound player and
observe the results.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_delay.arts</filename></term>
<listitem>
<para>
This is the same as <filename>example_cdelay.arts</filename> but used
the delay effect. 
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_capture_wav.arts</filename></term>
<listitem>
<para>
This uses the Synth_CAPTURE_WAV to save a 400 Hz sine wave as a wav
file. Run the module for a few seconds, and then examine the file
created in <filename class="directory">/tmp</filename>. You can play the
file with a player such as <application>kaiman</application>.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_data.arts</filename></term>
<listitem>
<para>
This uses the Data module to generate a constant stream of the value
<quote>3</quote> and sends it to a Debug module to periodically display
it. It also contains a Nil module, illustrating how it can be used to do
nothing at all.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_adsr.arts</filename></term>
<listitem>
<para>
Shows how to create a simple instrument sound using the Envelope Adsr
module, repetitively triggered by a square wave.  
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_fm.arts</filename></term>
<listitem>
<para>
This uses the FM Source module to generate a 440 Hz sine wave which is
frequency modulated at a 5 Hz rate.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_freeverb.arts</filename></term>
<listitem>
<para>
This connects the Freeverb effect from a bus downlink to a bus
outlink. You can use artscontrol to connect the effect to a sound player
and observe the results.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_flanger.arts</filename></term>
<listitem>
<para>
This implements a simple flanger effect (it doesn't appear to work yet,
though).
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_moog.arts</filename></term>
<listitem>
<para>
This structure combines the two channels from a bus into one, passes it
though the Moog VCF filter, and sends it out the out_soundcard bus.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_pitch_shift.arts</filename></term>
<listitem>
<para>
This structure passes the left channel of sound card data through the
Pitch Shift effect. Adjust the speed parameter to vary the effect.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_rc.arts</filename></term>
<listitem>
<para>
This structure passes a white noise generator though an RC filter and
out to the sound card. By viewing the FFT Scope display in artscontrol
you can see how this varies from an unfiltered noise waveform.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_sequence.arts</filename></term>
<listitem>
<para>
This demonstrates the Sequence module by playing a sequence of notes.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_shelve_cutoff.arts</filename></term>
<listitem>
<para>
This structure passes a white noise generator though a Shelve Cutoff
filter and out to the sound card. By viewing the FFT Scope display in
artscontrol you can see how this varies from an unfiltered noise
waveform.  
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_equalizer.arts</filename></term>
<listitem>
<para>
This demonstrates the Std_Equalizer module. It boosts the low and high
frequencies by 6 dB.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_tremolo.arts</filename></term>
<listitem>
<para>
This demonstrates the Tremolo effect. It modulates the left and right
channels using a 10 Hz tremolo.  
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_xfade.arts</filename></term>
<listitem>
<para>
This example mixes 440 and 880 Hz sine waves using a cross fader.
Adjust the value of the cross fader's percentage input from -1 to 1 to
control the mixing of the two signals.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_pscale.arts</filename></term>
<listitem>
<para>
This illustrates the Pscale module (I'm not sure if this is a
meaningful example).
</para>
</listitem>
</varlistentry>

<varlistentry>
<term><filename>example_play_wav.arts</filename></term>
<listitem>
<para>
This illustrates the Play Wave module. You will need to
enter the full path to a <literal role="extension">.wav</literal> file
as the filename parameter.
</para>
</listitem>
</varlistentry>

<varlistentry>
<term>example_multi_add.arts</term>
<listitem>
<para>
This shows the Multi Add module which accepts any number of inputs. It
sums three Data modules which produce inputs of 1, 2, and 3, and
displays the result 6.
</para>
</listitem>
</varlistentry>
</variablelist>

</sect1>
</chapter>