Audio Popping Question

beginners
#1

So, for the final project in a coding class I made a synth using the Maximilian add-on. It works great but half the time I launch it there’s an awful pop. I don’t no how to get rid of it and always just mute my computer when it’s launching. any ideas?

best,
jjb

#2

try ramping up the amplitude when the application starts instead of generating sound at the maximum amplitude right away.

#3

@arturo yeah, I saw that mentioned in the of book page about audio. How do I implement that?

#4

just multiply the signal by a number increasing from 0 to 1

#5

would you mind showing me an example of that I still can’t get it to work. I tried 03%20AM

#6

with 2 being the number of channels and that done in setup.

#7

yes that’s pretty much it but with j starting at 0, doing it in the audio callback and declaring j in the .h so you can keep increasing it until it reaches 1. also don’t forget to clamp j between 0 and 1

depending on the increment of j the ramp up will be slower or faster usually 100ms is more than enough

#8

This will not ramp the volume, instead it is just setting the value stored in the buffer.

It should be something like:
in the .h file place the following:

float volumeRamp = 0;
bool bNeedsVolumeRamp = true;

then in the audio callback function, which probably is void ofApp::audioOut(ofSoundBuffer & buffer)
put the following at the end of the function, after you’ve done any processing of the audio signal

size_t nChans =buffer.getNumChannels();
if(bNeedsVolumeRamp){
	for (size_t i = 0; i < buffer.getNumFrames(); i++){
		for(size_t j = 0; j < nChans; j++){
			buffer[i*nChans + j] *= volumeRamp;
		}
		volumeRamp += 0.01; // adjust this value to change how much time it takes to make the ramp.
		if(volumeRamp > 1.0f){
			volumeRamp = 1.0f;
		}
	}
	if(ofIsFloatEqual(volumeRamp,1.0f)){
		bNeedsVolumeRamp = false;
	}
}
#9

oh yeah sorry i didn’t realized it was just setting the value not multiplying

1 Like
#10

I’ve had a lot of success and fixing audio popping issues by using a ofScopedLock() in the whole ofApp::AudioOut when dealing with dynamic variables that drive audio parameters, specially using Maximillian. You might want to implement that as well!

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#11

well that’s something you need to do if you are going to use dynamic variables that are being modified elsewhere as the audio callbacks are running in a different thread. It is also relevant to the popping audio the way in which the dynamic variables change; if these have abrupt changes it might become into a kind of pop, but that depends on what you are doing with these. In order to avoid such abrupt changes you can use some kind of smoothing.