Android Audio recording, MediaRecorder example

activity_recording.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@color/grey50">

    <LinearLayout
        android:id="@+id/button_bar"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/timer"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

        <Button
            android:id="@+id/cancel_button"
            style="?android:attr/borderlessButtonStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="@string/cancel"
            android:textColor="@color/black87" />

        <View
            android:layout_width="1dp"
            android:layout_height="fill_parent"
            android:layout_marginBottom="7dp"
            android:layout_marginTop="7dp"
            android:background="@color/black12" />

        <Button
            android:id="@+id/share_button"
            style="?android:attr/borderlessButtonStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="@string/share"
            android:textColor="@color/black87" />
    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="50sp"
        android:text="0:00.0"
        android:textColor="@color/red3000"
        android:typeface="monospace"
        android:textStyle="bold"
        android:id="@+id/timer"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"/>
</RelativeLayout>

RecordingActivity.java

/**
 * @author Chathura Wijesinghe <cdanasiri@gmail.com> on 9/9/15.
 */
public class RecordingActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView mTimerTextView;
    private Button mCancelButton;
    private Button mStopButton;

    private MediaRecorder mRecorder;
    private long mStartTime = 0;

    private int[] amplitudes = new int[100];
    private int i = 0;

    private Handler mHandler = new Handler();
    private Runnable mTickExecutor = new Runnable() {
        @Override
        public void run() {
            tick();
            mHandler.postDelayed(mTickExecutor,100);
        }
    };
    private File mOutputFile;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recording);
        this.mTimerTextView = (TextView) this.findViewById(R.id.timer);
        this.mCancelButton = (Button) this.findViewById(R.id.cancel_button);
        this.mCancelButton.setOnClickListener(this);
        this.mStopButton = (Button) this.findViewById(R.id.share_button);
        this.mStopButton.setOnClickListener(this);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.d("Voice Recorder", "output: " + getOutputFile());
        startRecording();
    }

    @Override
    protected void onStop() {
        super.onStop();
        if (mRecorder != null) {
            stopRecording(false);
        }
    }

    private void startRecording() {
        mRecorder = new MediaRecorder();
        mRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.HE_AAC);
            mRecorder.setAudioEncodingBitRate(48000);
        } else {
            mRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
            mRecorder.setAudioEncodingBitRate(64000);
        }
        mRecorder.setAudioSamplingRate(16000);
        mOutputFile = getOutputFile();
        mOutputFile.getParentFile().mkdirs();
        mRecorder.setOutputFile(mOutputFile.getAbsolutePath());

        try {
            mRecorder.prepare();
            mRecorder.start();
            mStartTime = SystemClock.elapsedRealtime();
            mHandler.postDelayed(mTickExecutor, 100);
            Log.d("Voice Recorder","started recording to "+mOutputFile.getAbsolutePath());
        } catch (IOException e) {
            Log.e("Voice Recorder", "prepare() failed "+e.getMessage());
        }
    }

    protected  void stopRecording(boolean saveFile) {
        mRecorder.stop();
        mRecorder.release();
        mRecorder = null;
        mStartTime = 0;
        mHandler.removeCallbacks(mTickExecutor);
        if (!saveFile && mOutputFile != null) {
            mOutputFile.delete();
        }
    }

    private File getOutputFile() {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd_HHmmssSSS", Locale.US);
        return new File(Environment.getExternalStorageDirectory().getAbsolutePath().toString()
                + "/Voice Recorder/RECORDING_"
                + dateFormat.format(new Date())
                + ".m4a");
    }

    private void tick() {
        long time = (mStartTime < 0) ? 0 : (SystemClock.elapsedRealtime() - mStartTime);
        int minutes = (int) (time / 60000);
        int seconds = (int) (time / 1000) % 60;
        int milliseconds = (int) (time / 100) % 10;
        mTimerTextView.setText(minutes+":"+(seconds < 10 ? "0"+seconds : seconds)+"."+milliseconds);
        if (mRecorder != null) {
            amplitudes[i] = mRecorder.getMaxAmplitude();
            //Log.d("Voice Recorder","amplitude: "+(amplitudes[i] * 100 / 32767));
            if (i >= amplitudes.length -1) {
                i = 0;
            } else {
                ++i;
            }
        }
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.cancel_button:
                stopRecording(false);
                setResult(RESULT_CANCELED);
                finish();
                break;
            case R.id.share_button:
                stopRecording(true);
                Uri uri = Uri.parse("file://" + mOutputFile.getAbsolutePath());
                Intent scanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
                scanIntent.setData(uri);
                sendBroadcast(scanIntent);
                setResult(Activity.RESULT_OK, new Intent().setData(uri));
                finish();
                break;
        }
    }
}