Tremolo Patch

OWL Patches
#1

Simple sine wave tremolo with adjustable frequency and gain!

#define m_SR 44100
class TremoloPatch : public SampleBasedPatch {
private:
  double omega;
public:
  TremoloPatch() : omega(0) {}
  void processAudio(AudioInputBuffer &input, AudioOutputBuffer &output){
    float phi, gain;
    getParameterValue(PARAMETER_A, phi);
    getParameterValue(PARAMETER_B, gain);
    int size = input.getSize();
    float buf[size];
    input.getSamples(0, size, buf);
    for(int i=0; i<size; ++i){
      omega += phi * 10 * 2*PI / m_SR;
      buf[i] = (float)(((1 + cos(omega))/2) * buf[i] * gain);
    }
    output.setSamples(0, size, buf);
  }
};
#2

Been trying to get this patch working in VC++2012 but am having some problems with the buffer allocation

#ifndef __TremoloPatch_hpp__
#define __TremoloPatch_hpp__
#define _USE_MATH_DEFINES
#define m_SR 44100

#include &quot;StompBox.h&quot;
#include &lt;math.h&gt;

class TremoloPatch : public Patch {
private:
  double omega;
public:
  TremoloPatch() : omega(0) {}
  void processAudio(AudioInputBuffer &amp;input, AudioOutputBuffer &amp;output){
	float phi = getParameterValue(PARAMETER_A);
    float gain = getParameterValue(PARAMETER_B);
    int size = input.getSize();
    float buf[size];
    input.getSamples(0, size, buf);
    for(int i=0; i&lt;size; ++i){
      omega += phi * 10 * 2*M_PI / m_SR;
      buf[i] = (float)(((1 + cos(omega))/2) * buf[i] * gain);
    }
    output.setSamples(0, size, buf);
  }
};

#endif // __TremoloPatch_hpp__

I get the build error “error C2057: expected constant expression” in relation to float buf[size];

Any idea how to get around this?

#3

Seb, try this:

…
int size = input.getSize();
float* buf = input.getSamples();
…

Got no errors in vc++2012.

#4

Worked a dream. Here’s the patch for record```

#ifndef TremoloPatch_hpp
#define TremoloPatch_hpp
#define _USE_MATH_DEFINES
#define m_SR 44100

#include "StompBox.h"
#include <math.h>

class TremoloPatch : public Patch {
private:
double omega;
public:
TremoloPatch() : omega(0) {}
void processAudio(AudioInputBuffer &input, AudioOutputBuffer &output){
float phi = getParameterValue(PARAMETER_A);
float gain = getParameterValue(PARAMETER_B);
int size = input.getSize();
float* buf = input.getSamples();
input.getSamples(0, size, buf);
for(int i=0; i<size; ++i){
omega += phi * 10 * 2*M_PI / m_SR;
buf[i] = (float)(((1 + cos(omega))/2) * buf[i] * gain);
}
output.setSamples(0, size, buf);
}
};

#endif // __TremoloPatch_hpp__
#5

Is there an audio sample of this patch at work? I’m excited to hear some of the sounds people are creating!

#6

Gonna record some samples of this patch tomorrow.

#7

Something like this. Nothing special, but intresting and simple. I think, I have to add depth control into this patch.