I want to make a spectrum analyzer from a played audio file. Before it, i've tried to make a spectrum analyzer from MIC input and here's the part of the code:
private class RecordAudio extends AsyncTask<Void, double[], Void> {
@Override
protected Void doInBackground(Void... params) {
if(isCancelled()){
return null;
}
//try {
int bufferSize = AudioRecord.getMinBufferSize(frequency, channelConfiguration, audioEncoding);
AudioRecord audioRecord = new AudioRecord(
MediaRecorder.AudioSource.MIC, frequency, channelConfiguration, audioEncoding, bufferSize);
short[] buffer = new short[blockSize];
double[] toTransform = new double[blockSize];
try {
audioRecord.startRecording();
}
catch (IllegalStateException e) {
Log.e("Recording Failed", e.toString());
}
while (started) {
int bufferReadResult = audioRecord.read(buffer, 0, blockSize);
for (int i = 0; i < blockSize && i < bufferReadResult; i++) {
toTransform[i] = (double) buffer[i] / 32768.0; // signed 16 bit
}
transformer.ft(toTransform);
publishProgress(toTransform);
//Log.e("AudioRecord", "Recording Failed");
//return null;
}
//return null;
return null;
}
protected void onProgressUpdate(double[]... toTransform) {
canvas.drawColor(Color.BLACK);
for (int i = 0; i < toTransform[0].length; i++) {
int x;
x = i;
int downy = (int) (100 - (toTransform[0][i] * 10));
int upy = 100;
canvas.drawRect(x * 5, downy, x * 5 + 4, upy, paint);
//canvas.drawLine(x, downy, x, upy, paint);
imageView.invalidate();
}
}
From that code, I think that the FFT class needs the PCM data that we get from encoding sound input from the MIC. Now, how can I get the buffer size from played audio file and encode it to PCM? Can I use mediaCodec class?
I tried this code for my audio player :
public class PlayAudioExample extends ListActivity {
private static final int UPDATE_FREQUENCY = 500;
private static final int STEP_VALUE = 4000;
private MediaCursorAdapter mediaAdapter = null;
private TextView selelctedFile = null;
private SeekBar seekbar = null;
private MediaPlayer player = null;
private ImageButton playButton = null;
private ImageButton prevButton = null;
private ImageButton nextButton = null;
private boolean isStarted = true;
private String currentFile = "";
private boolean isMoveingSeekBar = false;
private final Handler handler = new Handler();
private final Runnable updatePositionRunnable = new Runnable() {
public void run() {
updatePosition();
}
};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
selelctedFile = (TextView)findViewById(R.id.selectedfile);
seekbar = (SeekBar)findViewById(R.id.seekbar);
playButton = (ImageButton)findViewById(R.id.play);
prevButton = (ImageButton)findViewById(R.id.prev);
nextButton = (ImageButton)findViewById(R.id.next);
player = new MediaPlayer();
player.setOnCompletionListener(onCompletion);
player.setOnErrorListener(onError);
seekbar.setOnSeekBarChangeListener(seekBarChanged);
Cursor cursor = getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
if(null != cursor)
{
cursor.moveToFirst();
mediaAdapter = new MediaCursorAdapter(this, R.layout.listitem, cursor);
setListAdapter(mediaAdapter);
playButton.setOnClickListener(onButtonClick);
nextButton.setOnClickListener(onButtonClick);
prevButton.setOnClickListener(onButtonClick);
}
}
@Override
protected void onListItemClick(ListView list, View view, int position, long id) {
super.onListItemClick(list, view, position, id);
currentFile = (String) view.getTag();
startPlay(currentFile);
}
@Override
protected void onDestroy() {
super.onDestroy();
handler.removeCallbacks(updatePositionRunnable);
player.stop();
player.reset();
player.release();
player = null;
}
private void startPlay(String file) {
Log.i("Selected: ", file);
selelctedFile.setText(file);
seekbar.setProgress(0);
player.stop();
player.reset();
try {
player.setDataSource(file);
player.prepare();
player.start();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
seekbar.setMax(player.getDuration());
playButton.setImageResource(android.R.drawable.ic_media_pause);
updatePosition();
isStarted = true;
}
private void stopPlay() {
player.stop();
player.reset();
playButton.setImageResource(android.R.drawable.ic_media_play);
handler.removeCallbacks(updatePositionRunnable);
seekbar.setProgress(0);
isStarted = false;
}
private void updatePosition(){
handler.removeCallbacks(updatePositionRunnable);
seekbar.setProgress(player.getCurrentPosition());
handler.postDelayed(updatePositionRunnable, UPDATE_FREQUENCY);
}
private class MediaCursorAdapter extends SimpleCursorAdapter{
public MediaCursorAdapter(Context context, int layout, Cursor c) {
super(context, layout, c,
new String[] { MediaStore.MediaColumns.DISPLAY_NAME, MediaStore.MediaColumns.TITLE, MediaStore.Audio.AudioColumns.DURATION},
new int[] { R.id.displayname, R.id.title, R.id.duration });
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
TextView title = (TextView)view.findViewById(R.id.title);
TextView name = (TextView)view.findViewById(R.id.displayname);
TextView duration = (TextView)view.findViewById(R.id.duration);
name.setText(cursor.getString(
cursor.getColumnIndex(MediaStore.MediaColumns.DISPLAY_NAME)));
title.setText(cursor.getString(
cursor.getColumnIndex(MediaStore.MediaColumns.TITLE)));
long durationInMs = Long.parseLong(cursor.getString(
cursor.getColumnIndex(MediaStore.Audio.AudioColumns.DURATION)));
double durationInMin = ((double)durationInMs/1000.0)/60.0;
durationInMin = new BigDecimal(Double.toString(durationInMin)).setScale(2, BigDecimal.ROUND_UP).doubleValue();
duration.setText("" + durationInMin);
view.setTag(cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DATA)));
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(context);
View v = inflater.inflate(R.layout.listitem, parent, false);
bindView(v, context, cursor);
return v;
}
}
private View.OnClickListener onButtonClick = new View.OnClickListener() {
@Override
public void onClick(View v) {
switch(v.getId())
{
case R.id.play:
{
if(player.isPlaying())
{
handler.removeCallbacks(updatePositionRunnable);
player.pause();
playButton.setImageResource(android.R.drawable.ic_media_play);
}
else
{
if(isStarted)
{
player.start();
playButton.setImageResource(android.R.drawable.ic_media_pause);
updatePosition();
}
else
{
startPlay(currentFile);
}
}
break;
}
case R.id.next:
{
int seekto = player.getCurrentPosition() + STEP_VALUE;
if(seekto > player.getDuration())
seekto = player.getDuration();
player.pause();
player.seekTo(seekto);
player.start();
break;
}
case R.id.prev:
{
int seekto = player.getCurrentPosition() - STEP_VALUE;
if(seekto < 0)
seekto = 0;
player.pause();
player.seekTo(seekto);
player.start();
break;
}
}
}
};
private MediaPlayer.OnCompletionListener onCompletion = new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
stopPlay();
}
};
private MediaPlayer.OnErrorListener onError = new MediaPlayer.OnErrorListener() {
@Override
public boolean onError(MediaPlayer mp, int what, int extra) {
// returning false will call the OnCompletionListener
return false;
}
};
private SeekBar.OnSeekBarChangeListener seekBarChanged = new SeekBar.OnSeekBarChangeListener() {
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
isMoveingSeekBar = false;
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
isMoveingSeekBar = true;
}
@Override
public void onProgressChanged(SeekBar seekBar, int progress,boolean fromUser) {
if(isMoveingSeekBar)
{
player.seekTo(progress);
Log.i("OnSeekBarChangeListener","onProgressChanged");
}
}
};
}
Really need help
Thanks 
