Sinewave Generator Produces Horrible Buzz

Getting Started
1

Hello I’m a newbie here and I can’t seem to even create a proper sinewave generator.
Could someone please point out what’s wrong with my code? It sort of works but always produces a horrible buzzing sound. The sliders and variables are all setup properly. So I’m thinking it has something to do with my getNextAudioBlock function:

void MainComponent::getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill)
{
    bufferToFill.clearActiveBufferRegion();
    for (int channel = 0; channel < bufferToFill.buffer->getNumChannels(); ++channel){
		auto* buffer = bufferToFill.buffer->getWritePointer(channel,bufferToFill.startSample);
		for (auto sample = 0; sample < bufferToFill.numSamples; ++sample) {
			buffer[sample] = std::sin(  sample * MathConstants<double>::twoPi * frequencySlider.getValue() / currentSampleRate  ) * (  volumeSlider.getValue() / 100  );
		}
		
	}
}
2

You need to use a modulo counter in the sine calculation, not the sample index of the current buffer.

3

The phase of your sinewave starts over again with each call of getNextAudioBlock(...) as it starts with zero (auto sample = 0) -> your sine starts from 0, this causes your buzzing.

To avoid that, you need a member variable like phase, which you increment for each sample by the right amount. This tutorial will help you: https://docs.juce.com/master/tutorial_sine_synth.html

BTW: When you write ``` before and after your code, it will be formatted nicely.

1 Like
4

Thank you! It worked!