Android Audio Recording Tutorial

After many hours of trying to record audio on my Google Android device, I’ve finally arrived at a workable solution. There were a few bumps along the way besides the horribly out of date MediaRecorder documentation, which was sorely lacking details. For one, I could only get audio to record to the SD card. Additionally, the directory being recorded to must already exist before attempting to record to it. Without further ado, here is a complete example for recording audio on the Android via the MediaRecorder API:

package com.benmccann.android.hello;

import java.io.File;
import java.io.IOException;

import android.media.MediaRecorder;
import android.os.Environment;

/**
* @author Ben McCann
*/
public class AudioRecorder {

final MediaRecorder recorder = new MediaRecorder();
final String path;

/**
* Creates a new audio recording at the given path (relative to root of SD card).
*/
public AudioRecorder(String path) {
this.path = sanitizePath(path);
}

private String sanitizePath(String path) {
if (!path.startsWith(“/”)) {
path = “/” + path;
}
if (!path.contains(“.”)) {
path += “.3gp”;
}
return Environment.getExternalStorageDirectory().getAbsolutePath() + path;
}

/**
* Starts a new recording.
*/
public void start() throws IOException {
String state = android.os.Environment.getExternalStorageState();
if(!state.equals(android.os.Environment.MEDIA_MOUNTED)) {
throw new IOException(“SD Card is not mounted. It is ” + state + “.”);
}

// make sure the directory we plan to store the recording in exists
File directory = new File(path).getParentFile();
if (!directory.exists() && !directory.mkdirs()) {
throw new IOException(“Path to file could not be created.”);
}

recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
recorder.setOutputFile(path);
recorder.prepare();
recorder.start();
}

/**
* Stops a recording that has been previously started.
*/
public void stop() throws IOException {
recorder.stop();
recorder.release();
}

}

Posted in: android tutorial