Record audio input

General JUCE discussion
1

Hi everyone,

I want to record the audio input. I think I have to use the AudioIODevice but I’m not sure how to use it… I get the audio input with the getDeviceNames() method, then I create one audioIODevice object, using the device name, and after that I don’t know how to use the “open” method" and the AudioIODeviceCallback class… Can somebody help me?
Thanx

Leskimo

2

I wrote quite a lot of comments for those classes - which bits are you finding confusing?

3

In fact, I don’t know how to find the two first parameters:

If I can make the “open” method work, do these next steps are good to record input?

  • Call the “start” method of AudioIODevice, with a subclass of AudioIODeviceCallback for parameter.

  • then I will be able to get the input in the "audioDeviceIOCallBack method of my AudioIODeviceCallBack class.

Is that Right?

Thanx for your help

Leskimo

4

Yes, that’s it.

5

great, so how do I set the first and second parameters of the “open” method?
My input has two channels (L and R), and I want to enable both channels, so how does the BitArray must be to do it? Sorry if I’m a bit slow to understand…

Leskimo

6

ok, that was a dumb question… I suppose If I want to enable the channel 0 and the channel 1, I have to set my BitArray like this: 0000 0011

Leskimo

7

Hi again,

seems like the opening is working, but the audioDeviceIOCallback is not called… Here’s my code:

[code] StringArray tab = AudioIODevice::getDeviceNames();

AudioIODevice device(tab[0]);  // 0 is for the Mic input

StringArray chanTab = device.getInputChannelNames();
double SampleRate = device.getSampleRate(0);   // 44100
int bufferSize = device.getDefaultBufferSize();

String error = device.open(BitArray(3),BitArray(3),device.getSampleRate(0),device.getDefaultBufferSize());  // BitArray(3), 3 because I want the first and the second channels (0000 0011)

if (error.isEmpty())
	printf("device opening was succesfull\n\n");
else
	printf("device opening failed. Return value: %s\n\n", toCString(error));

device.start(mpCallBack);  // mpCallBack is created in the constructor of this class[/code]

The audioDeviceAboutToStart method is called nut not he callback method… Does anyone see what I did wrong? Thanx in advance.

Leskimo

8

Looks ok, but what does your app do after this code? What’s the object that’s getting called back?

9

Oh - I just noticed that your AudioDevice object is on the stack… doh!

I’d also recommend the AudioDeviceManager class as a better option than using a device directly. And always put a spaces after your commas.

10

[code]AudioStuff::AudioStuff()
{
mpData = new tThreadData();
mpData->mGoOn = true;
mpCallBack = new AudioCallBack();
}

AudioStuff::~AudioStuff()
{
}

char* toCString(String str)
{
int length = str.length();
char* res = new char[length+1];

int i;
for (i = 0; i < length; i++)
	res[i] = str[i];

res[i] = '\0';
return res;

}

void AudioStuff::LaunchProcess()
{
StringArray tab = AudioIODevice::getDeviceNames();

AudioIODevice device(tab[0]);  // 0 is for the Mic input

StringArray chanTab = device.getInputChannelNames();
double SampleRate = device.getSampleRate(0);   // 44100
int bufferSize = device.getDefaultBufferSize();

String error = device.open(BitArray(3),BitArray(3),device.getSampleRate(0),device.getDefaultBufferSize());  // BitArray(3), 3 because I want the first and the second channels (0000 0011)

if (error.isEmpty())
	printf("device opening was succesfull\n\n");
else
	printf("device opening failed. Return value: %s\n\n", toCString(error));

device.start(mpCallBack);  // mpCallBack is created in the constructor of this class

}[/code]

here is the code of the class which create and open a device.
My callback class is like this:

[code]void AudioCallBack::audioDeviceIOCallback(const float **inputChannelData, int totalNumInputChannels, float **outputChannelData, int totalNumOutputChannels, int numSamples)
{
printf(“callback\n”);
}

void AudioCallBack::audioDeviceAboutToStart(double sampleRate, int numSamplesPerBlock)
{
printf(“about to start, sampleRate:%f, nbSamplePerBlock:%d\n”, sampleRate, numSamplesPerBlock);
}

void AudioCallBack::audioDeviceStopped()
{
}[/code]

I thought that when I called the “start” method, it called automatically my callback function, but It seems that it’s not the case, or maybe I’m missing something…

Leskimo

11

start() doesn’t block - callbacks are asynchronous. As soon as your start() call returns, your audio object goes out of scope, gets deleted and hence no callbacks…

12

thank you so much for your help. It works perfectly.

Leskimo