How to record audio/voice in background continuously in android?

Question

As I want to record audio in background I use service..But I am not able to record the audio in service.

I tried same code in Activity it works for me. but how to do audio recording in background when voice /speech is input that means audio recording should start if there is voice input and that should be in background...?

Answer 1

In one of my project I had this requirement to continuously record audio from Microphone. I can not share the project but I can share the specific AudioRecorder class.

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import android.content.Context;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.util.Log;

    public class AudioRecorder {
        public enum State {
            INITIALIZING,
            READY,
            RECORDING,
            ERROR,
            STOPPED
        };
        private byte[] audioBuffer = null;
        private int source = MediaRecorder.AudioSource.MIC;
        private int sampleRate = 0;
        private int encoder = 0;
        private int nChannels = 0;
        private int bufferRead = 0;
        private int bufferSize = 0;
        private RandomAccessFile tempAudioFile = null;
        public AudioRecord audioRecorder = null;
        private State state;
        private short bSamples = 16;
        private int framePeriod;

        // The interval in which the recorded samples are output to the file
        // Used only in uncompressed mode
        private static final int TIMER_INTERVAL = 120;
        volatile Thread t = null;
        public int TimeStamp = 0, count = 0, preTimeStamp = 0;

        public AudioRecorder(Context c) {
            this.sampleRate = 11025;
            this.encoder = AudioFormat.ENCODING_PCM_16BIT;
            this.nChannels = AudioFormat.CHANNEL_CONFIGURATION_MONO;
            this.preTimeStamp = (int) System.currentTimeMillis();
            myApp = (MyApp) c.getApplicationContext();
            mQueue = myApp.getQueue();

            try {
                /*          
                    String fileName = "/sdcard/XYZ/11025.wav";
                    tempAudioFile = new RandomAccessFile(fileName,"rw");
                */

                framePeriod = sampleRate * TIMER_INTERVAL / 1000;
                bufferSize = framePeriod * 2 * bSamples * nChannels / 8;

                if (bufferSize < AudioRecord.getMinBufferSize(sampleRate, nChannels, encoder)) {
                    bufferSize = AudioRecord.getMinBufferSize(sampleRate, nChannels, encoder);

                    // Set frame period and timer interval accordingly
                    framePeriod = bufferSize / (2 * bSamples * nChannels / 8);
                    Log.w(AudioRecorder.class.getName(), "Increasing buffer size to " + Integer.toString(bufferSize));
                }

                audioRecorder = new AudioRecord(source, sampleRate, nChannels, encoder, bufferSize);
                audioBuffer = new byte[2048];
                audioRecorder.setRecordPositionUpdateListener(updateListener);
                audioRecorder.setPositionNotificationPeriod(framePeriod);
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }

        private AudioRecord.OnRecordPositionUpdateListener updateListener = new AudioRecord.OnRecordPositionUpdateListener() {
            @Override
            public void onPeriodicNotification(AudioRecord recorder) {
                //          Log.d(Constant.APP_LOG,"Into Periodic Notification...");
            }
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            */
        }

        @Override
        public void onMarkerReached(AudioRecord recorder) {
            // TODO Auto-generated method stub
        }
    };

    public void start() {
        if (state == State.INITIALIZING) {
            audioRecorder.startRecording();
            state = State.RECORDING;

            t = new Thread() {
                public void run() {
                    //Here You can read your Audio Buffers
                    audioRecorder.read(audioBuffer, 0, 2048);
                }
            };

            t.setPriority(Thread.MAX_PRIORITY);
            t.start();
        } else {
            Log.e(AudioRecorder.class.getName(), "start() called on illegal state");
            state = State.ERROR;
        }
    }

    public void stop() {
        if (state == State.RECORDING) {
            audioRecorder.stop();
            Thread t1 = t;
            t = null;
            t1.interrupt();
            count = 0;
            state = State.STOPPED;
        } else {
            Log.e(AudioRecorder.class.getName(), "stop() called on illegal state");
            state = State.ERROR;
        }
    }

    public void release() {
        if (state == State.RECORDING) {
            stop();
        }

        if (audioRecorder != null) {
            audioRecorder.release();
        }
    }

    public void reset() {
        try {
            if (state != State.ERROR) {
                release();
            }
        } catch (Exception e) {
            Log.e(AudioRecorder.class.getName(), e.getMessage());

            state = State.ERROR;
        }
    }

    public State getState() {
        return state;
    }
}

Now, Create Service and just call start() method and manipulate your recorded audio buffer for your purpose.

Hope it will Help you.

Answer 2

For starting the recording in backgroun you can either

• create a thread and do the recording inside a thread.

• create a service which will run in background.

Hope it helps.

Edit 1

Thread recordInBackGround= new Thread(new Runnable() {
                    @Override
                    public void run() { 
//Your recording portion of the code goes here.
}
});

recordInBackGround.start();