Bilinear Transform: RC Lowpass

IIR Filters

FIR Filters

Plans and Directions

The original SPRAWL System was designed as a means for enhanced interaction in Local Area Networks (LAN) (read more). Due to the needs for online teaching and musical performance in 2020, the concept was extended to a Wide Area Network (WAN) solution. In the coming months, the project with be extended in a cooperation with LTU, Sweden and Ritmo, Oslo. The following areas can be tackled in this period.

Multichannel Clients

In this semester we will extend the system to incorporate clients and endpoints with difeerent configurations, including larger loudspeaker setups:


Extended SPRAWL System, allowing Access Points with different configurations.

Gestural Control

All three sites in the project will be equipped with a motion tracking system and multichannel loudspeaker setups, using different configurations. Experiments will aim at sharing spatial sound between the sites and manipulating them with gestural input.


21 channel Ambisonics setup with motion capturing system at BOL.

Clocking and Syncing

Another focus will be experiments with shared clocks and sequences, in cooperation with the RITMO group in Oslo:

We have the possibility to join the Rhythm Production and Perception Workshop for our closing concert on June 22-25.

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Playing Samples in SuperCollider

The Buffer class manages samples in SuperCollider. There are many ways to use samples, based on these buffers. The following example loads a WAV file (find it in the download) and creates a looping node. When running, the playback speed can be changed:


// get and enter the absolute path to a sample
~sample_path = "/some/directory/sala_formanten.wav";

~buffer  =,~sample_path);

~sampler = {

      |rate= 0.1|

      var out =,~buffer.bufnum, * rate, 1, 0,0,~buffer.numFrames);, out);



// set the play rate manually



Combine the sample looper example with the control bus and mouse input example to create a synth for scratching sound files.

Sending OSC from SuperCollider

For sending OSC from SuperCollider, a NetAddr object needs to be generated. It needs an IP address and a port:

~out_address  = NetAddr("", 6666);

Sending Values Once

This first example sends an OSC message once when the following line is evaluated. The previously created NetAddr object can be used to send OSC messages with its sendMsg method:

~out_address.sendMsg('/test/message', 1);

Sending Values Continuously

Based on the previous example, a routine can be created which continuously reads values from control rate buses to send their instantaneous value via OSC. The osc_routine runs an infinite loop with a short wait interval to limit the send rate and the CPU load:

  ~cBus = Bus.control(s,1);

  ~osc_routine = Routine({{

      // read value from bus
                  var value      = ~cBus.getSynchronous(~nVbap);

      // send value
                  ~out_address.sendMsg('/oscillator/frequency', value);

                  // wait


Once created, the routine can be started and stopped with the methods play() and stop(). While running, bus values can be changed to test the functionality:;






Run the PD patch osc-receive.pd to receive values from SuperCollider via OSC and control the pitch.

Laplace Transform

Receiving OSC in SuperCollider

By default, a running instance of sclang listens to incoming OSC messsages on the port 57120.


For listening to a specific OSC message, an OSC function can be defined with the matching path:

 ~osc_receive = OSCFunc(

         { arg msg, time, addr, recvPort;

postln('Revceived message: '+msg[0].string' - '+msg[1].string);

 }, '/test/message');


OSCdef is slightly more flexible and allows to change definitions on the fly, without deleting nodes:

              {|msg, time, addr, recvPort|
                      var val;
                      val = msg[1];
      },'/test/another', n);

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