Faust: Splitting and Merging Signals

To Stereo

The <: operator can be used to split a signal into an arbitrary number of branches. This is frequently used to send a signal to both the left and the right channel of a computer's output device. In the following example, an impulse train with a frequency of $5\ \mathrm{Hz}$ is generated and split into a stereo signal.

import("stdfaust.lib");

// a source signal
signal = os.imptrain(5);

// split signal to stereo in process function:
process = signal <: _,_;

To Many

The splitting operator can be used to create more than just two branches. The following example splits the source signal into 8 signals:

To achieve this, the splitting directive can be extended by the desired number of outputs:

process = signal <: _,_,_,_,_,_,_,_;

Merging to Single

The merging operator :> in Faust is the inversion of the splitting operator. It can combine an arbitrary number of signals to a single output. In the following example, four individual sine waves are merged:

Input signals are separated by commas and then joined with the merging operator.

import("stdfaust.lib");

// create four sine waves
// with arbitrary frequencies
s1 = 0.2*os.osc(120);
s2 = 0.2*os.osc(340);
s3 = 0.2*os.osc(1560);
s4 = 0.2*os.osc(780);

// merge them to two signals
process = s1,s2,s3,s4 :> _;

Merging to Multiple

Merging can be used to create multiple individual signals from a number of input signals. The following example generates a stereo signal with individual channels from the four sine waves:

To achieve this, two output signals need to be assigned after merging:

// merge them to two signals
process = s1,s2,s3,s4 :> _,_;

Exercise