Microphone on Android

in Android Processing • 10 months ago

Hello,

I have a sketch that uses Minim's lineIn to capture volume from the microphone. I'd like to put it on Android. I see that Minim can't be used in Android -- can someone please recommend a good way to get similar behavior?

Thank you!

Hélène.

Replies(9)

andres

Re: Microphone on Android

10 months ago

I don't have experience with sound on Android, but you can access any class from the Android SDK in your Processing sketch, and the SDK has audio recording capabilities. Maybe this helps.

lognaturel

Re: Microphone on Android

10 months ago

Thanks, Andres! I'm still hoping there's something a little more elegant (I'd rather not have to record the audio if I don't have to) but it looks like this may be my best bet.

lognaturel

Re: Microphone on Android

10 months ago

Here's what I've ended up with. Recommendations appreciated and I hope it can help someone else out.

<edit: added the stop method following Jesse's comment.>

<edit: you'll need to include the following line in your AndroidManifest:

<uses-permission android:name="android.permission.RECORD_AUDIO"></uses-permission>
otherwise, you'll get the following error: "Error creating AudioRecord instance: initialization check failed.">

import android.media.AudioRecord;
import android.media.AudioFormat;
import android.media.MediaRecorder;
final int RECORDER_SAMPLERATE = 44100;
final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
short[] buffer = null;
AudioRecord audioRecord = null;
int bufferSize;
float volume = 0;
void setup() {
bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,RECORDER_CHANNELS,RECORDER_AUDIO_ENCODING);
audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,RECORDER_AUDIO_ENCODING, bufferSize);
audioRecord.startRecording();
buffer = new short[bufferSize];
}
void draw() {
background(200);
int bufferReadResult = audioRecord.read(buffer, 0, bufferSize);
volume = 0;
for (int i = 0; i < bufferReadResult; i++) {
volume = Math.max(Math.abs(buffer[i]), volume);
}
text("" + volume, 100, 100);
}
void stop() {
audioRecord.stop();
audioRecord.release();
}

Jesse Sco..

Re: Microphone on Android

10 months ago

I've never tried to just get the buffer... hmmm.

You never stop or null the recorder though... this will give you problems, as you're not releasing the microphone back to the OS so it can give it to other applications...

Slightly different implementation below, but this is the start/stop methods I use...

void startRecording() {
// Set Directory
recFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
recFileName += "/SonicDrift/" + tagLocation.getText() + ".3gp";
// Set MediaRecorder
mRecorder = new MediaRecorder();
mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mRecorder.setOutputFile(recFileName);
try {
mRecorder.prepare();
}
catch (IOException e) {
//e.printStackTrace();
}
mRecorder.start();
}
void stopRecording() {
saveToFile();
mRecorder.stop();
mRecorder.release();
mRecorder = null;
}

lognaturel

Re: Microphone on Android

10 months ago

Oops, you're right, thanks! I'll edit the code above so it's not misleading.

Jesse Sco..

Re: Microphone on Android

10 months ago

More particularly on Android you will want to call onPause() instead of stop(), as that's more in sync with the Activity lifecycle. Not sure if Processing still calls stop() within an Android activity.

Also make sure to set it to null after you release it, so it can be Garbage Collected...

But yeah, it works!

I guess if you never set it an output file, the buffer gets saved to a temp folder and trashed ??

Now to see if there's an FFT method!

ashleyjam..

Re: Microphone on Android

6 months ago

I am after the same thing - i cant get the code above to work.

In the console i get 'no library found for android.media'

It compiles and builds to my phone but then i get a fatal exception and it quits.

startrecording() called an uninitialised AudioRecord

Jesse Sco..

Re: Microphone on Android

6 months ago

Do you have the permission set as the edits point out in Helene's 4th post ??

swimgod

Re: Microphone on Android

2 months ago

FFT Implementation

Works great, just remember buffersize MUST be a power of 2. Also PCM_16BIT encoding is best. Also the bigger the buffersize the more time it takes to capture each burst. If you need more accuracy I would go with decreasing sample rate over increasing buffersize. Just keep in mind nyquist limits it to being able to analyze to half the sample rate and lower.

This library wants to see floats not integers like the ones provided by the buffer. So I just cycled through and mapped it correctly [for 16bit of course.]

map(buffer[i], -32768, 32767, -1,1);

I had a lot of problems getting my app to launch properly without complaining about stop calls.

Then I tried this.

@Override
void onStop() {
audioRecord.stop();
audioRecord.release();
super.onStop();
}

Also the permissions are set in the PDE under Android>Sketch Permissions, only one you need for basic audio stuff like setting up a buffer and doing an FFT analysis are RECORD_AUDIO

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