Monday, 17 September 2012

Audio Record Statically


The AudioRecord class manages the audio resources for Java applications to record audio from the audio input hardware of the platform. This is achieved by "pulling" (reading) the data from the AudioRecord object. The application is responsible for polling the AudioRecord object in time using one of the following three methods: read(byte[], int, int)read(short[], int, int) or read(ByteBuffer, int). The choice of which method to use will be based on the audio data storage format that is the most convenient for the user of AudioRecord.
Upon creation, an AudioRecord object initializes its associated audio buffer that it will fill with the new audio data. The size of this buffer, specified during the construction, determines how long an AudioRecord can record before "over-running" data that has not been read yet. Data should be read from the audio hardware in chunks of sizes inferior to the total recording buffer size.

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;

/**
 *
 * @author RAHUL BARADIA
 *
 *
 */
public class Audio_Record extends Activity {
private static final int RECORDER_SAMPLERATE = 8000;

private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;

private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

private AudioRecord recorder = null;
private Thread recordingThread = null;
private boolean isRecording = false;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

setButtonHandlers();
enableButtons(false);

int bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);
}

private void setButtonHandlers() {
((Button) findViewById(R.id.btnStart)).setOnClickListener(btnClick);
((Button) findViewById(R.id.btnStop)).setOnClickListener(btnClick);
}

private void enableButton(int id, boolean isEnable) {
((Button) findViewById(id)).setEnabled(isEnable);
}

private void enableButtons(boolean isRecording) {
enableButton(R.id.btnStart, !isRecording);
enableButton(R.id.btnStop, isRecording);
}

int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we use only 1024
int BytesPerElement = 2; // 2 bytes in 16bit format

private void startRecording() {

recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);

recorder.startRecording();
   
isRecording = true;

recordingThread = new Thread(new Runnable() {

public void run() {

writeAudioDataToFile();

}
}, "AudioRecorder Thread");
recordingThread.start();
}

        //Conversion of short to byte
private byte[] short2byte(short[] sData) {
int shortArrsize = sData.length;
byte[] bytes = new byte[shortArrsize * 2];

for (int i = 0; i < shortArrsize; i++) {
bytes[i * 2] = (byte) (sData[i] & 0x00FF);
bytes[(i * 2) + 1] = (byte) (sData[i] >> 8);
sData[i] = 0;
}
return bytes;
}

private void writeAudioDataToFile() {
// Write the output audio in byte
String filePath = "/sdcard/8k16bitMono.pcm";

                short sData[] = new short[BufferElements2Rec];

FileOutputStream os = null;
try {
os = new FileOutputStream(filePath);
} catch (FileNotFoundException e) {
e.printStackTrace();
}

while (isRecording) {
// gets the voice output from microphone to byte format
recorder.read(sData, 0, BufferElements2Rec);
System.out.println("Short wirting to file" + sData.toString());
try {
// writes the data to file from buffer stores the voice buffer
byte bData[] = short2byte(sData);

os.write(bData, 0, BufferElements2Rec * BytesPerElement);

} catch (IOException e) {
e.printStackTrace();
}
}

try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}

private void stopRecording() {
// stops the recording activity
if (null != recorder) {
isRecording = false;

 
recorder.stop();
recorder.release();

recorder = null;
recordingThread = null;
}
}

private View.OnClickListener btnClick = new View.OnClickListener() {
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStart: {
enableButtons(true);
startRecording();
break;
}
case R.id.btnStop: {
enableButtons(false);
stopRecording();
break;
}
}
}
};

        // onClick of backbutton finishes the activity.
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
finish();
}
return super.onKeyDown(keyCode, event);
}
}