Generating a sine oscillator

In this recipe, we will learn how to generatively create a sine wave oscillator by manipulating the sound card's PCM (Pulse-code Modulation ) audio buffer. The frequency of the sine wave will be defined by the mouse's y coordinate.

We will also draw the sine wave for a visual representation.

Getting ready

Include the following files:

#include "cinder/audio/Output.h"
#include "cinder/audio/Callback.h"
#include "cinder/Rand.h"
#include "cinder/CinderMath.h"

And add the following useful using statements:

using namespace ci;
using namespace ci::app;
using namespace std;

How to do it…

We will create a sine wave oscillator using the following steps:

1. Declare the following member variables and the callback method:

   void audioCallback( uint64_t inSampleOffset, uint32_t ioSampleCount, audio::Buffer32f *buffer );
   float mFrequency;
   float mPhase, mPhaseAdd;
   vector<float> mOutput;

2. In the setup module we will initialize the variables and create the audio callback using the following...