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更新时间：2022-10-15 15:50:42
如何与 Bandpass.java源代码，可能是由于看起来有点误解：IIR过滤器不是处理频率，而是处理时域数据样本（可能表现出振荡行为）。
因此，您必须提供那些时域样本作为 Bandpass.process（）。由于您正在从文件中读取原始字节，因此您需要将这些字节转换为 float 。你可以这样做：
/ **
*将原始音频转换为16位int格式。
* @param rawdata
* /
private int [] byteToShort（byte [] rawdata）{
int [] converted = new int [rawdata.length / 2];
（int i = 0; i< converted.length; i ++）{
// Wave文件数据以little-endian顺序存储
int lo = rawdata [ 2 * I];
int hi = rawdata [2 * i + 1];
转换[i] =（（hi& 0xFF）}
返回转换;
}
private float [] byteToFloat（byte [] audio）{
return shortToFloat（byteToShort（audio））;
}
另外，对于立体声波形文件，您将从波形文件交错。所以你也需要去交错样品。这可以通过与 deinterleaveData 类似的方式来实现，除非您需要一个转换为 float [] [] 而不是期望 double [] [] 自$ 当然你也需要在滤波之后将两个通道重新组合在一起，但在将产生的滤波信号反馈回 audioTrack ：
float [] interleaveData（float [] []]数据）{
int numChannels = data.length;
int numFrames = data [0] .length;
float [] result = new float [numFrames * numChannels]; （int ch = 0; ch
for（int i = 0; i
}
}
返回结果;
$ / code>
您现在应该有必要的构建块来过滤音频：
BandPass bandpass =新的BandPass（19000,2000,44100）;
while（（count = dataInputStream.read（data，0，bufferSize））> -1）{
//对每个采样数据解码和解交错立体声16位
float [] [ ] signals = deinterleaveData（byteToFloat（data），2）;
//过滤数据样本，用已过滤的样本更新缓冲区。
bandpass.process（signals [0]，signals [1]）;
//重新组合信号进行回放
audioTrack.write（interleaveData（signals），0，count，WRITE_NON_BLOCKING）;
}
P.S.: as a final note, you are currently reading all the wave file as data samples, header included. This will result in a short noisy burst at the beginning. To avoid this, you should skip the header.
How do I implement an IIR bandpass filter in my current android code? I have an android app which could record audio (frequency actually) and save it in a .wav file.
I have managed to find a IIR Filter Library online but I am not sure how to implement it into my code.
https://github.com/ddf/Minim/blob/master/src/ddf/minim/effects/BandPass.java https://github.com/DASAR/Minim-Android/blob/master/src/ddf/minim/effects/IIRFilter.java
I am supposed to add the 18k-20k bandpass filter to the code before outputting the received sound signal into a .wav file.
My current code
package com.example.audio;
import ddf.minim.effects.*;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import com.varma.samples.audiorecorder.R;
import android.app.Activity;
import android.content.Context;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.media.AudioTrack;
import android.media.MediaRecorder;
import android.media.MediaScannerConnection;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.text.SpannableStringBuilder;
import android.text.style.RelativeSizeSpan;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
public class RecorderActivity extends Activity {
private static final int RECORDER_BPP = 16;
private static final String AUDIO_RECORDER_FILE_EXT_WAV = ".wav";
private static final String AUDIO_RECORDER_FOLDER = "AudioRecorder";
private static final String AUDIO_RECORDER_TEMP_FILE = "record_temp.raw";
private static final int RECORDER_SAMPLERATE = 44100;// 44100; //18000
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_STEREO; //AudioFormat.CHANNEL_IN_STEREO;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
private static final int PLAY_CHANNELS = AudioFormat.CHANNEL_OUT_STEREO; //AudioFormat.CHANNEL_OUT_STEREO;
private static final int FREQUENCY_LEFT = 2000; //Original:18000 (16 Dec)
private static final int FREQUENCY_RIGHT = 2000; //Original:18000 (16 Dec)
private static final int AMPLITUDE_LEFT = 1;
private static final int AMPLITUDE_RIGHT = 1;
private static final int DURATION_SECOND = 10;
private static final int SAMPLE_RATE = 44100;
private static final float SWEEP_RANGE = 1000.0f;
String store;
private AudioRecord recorder = null;
private int bufferSize = 0;
private Thread recordingThread = null;
private boolean isRecording = false;
double time;
float[] buffer1;
float[] buffer2;
byte[] byteBuffer1;
byte[] byteBuffer2;
byte[] byteBufferFinal;
int bufferIndex;
short x;
short y;
AudioTrack audioTrack;
Button btnPlay, btnStart, btnStop;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setButtonHandlers();
enableButtons(false);
btnPlay = (Button) findViewById(R.id.btnPlay);
btnStop = (Button) findViewById(R.id.btnStop);
btnStart = (Button) findViewById(R.id.btnStart);
bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE, RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);
buffer1 = new float[(int) (DURATION_SECOND * SAMPLE_RATE)];
buffer2 = new float[(int) (DURATION_SECOND * SAMPLE_RATE)];
float f1 = 0.0f, f2 = 0.0f;
for (int sample = 0, step = 0; sample < buffer1.length; sample++) {
time = sample / (SAMPLE_RATE * 1.0);
//f1 = (float)(FREQUENCY_LEFT + ((sample / (buffer1.length * 1.0)) * SWEEP_RANGE)); // frequency sweep
//f2 = (float)(FREQUENCY_RIGHT + ((sample / (buffer1.length * 1.0)) * SWEEP_RANGE)); // frequency sweep
f1 = FREQUENCY_LEFT; // static frequency
f2 = FREQUENCY_RIGHT; // static frequency
buffer1[sample] = (float) (AMPLITUDE_LEFT * Math.sin(2 * Math.PI * f1 * time));
buffer2[sample] = (float) (AMPLITUDE_RIGHT * Math.sin(2 * Math.PI * f2 * time));
}
byteBuffer1 = new byte[buffer1.length * 2]; // two bytes per audio
// frame, 16 bits
for (int i = 0, bufferIndex = 0; i < byteBuffer1.length; i++) {
x = (short) (buffer1[bufferIndex++] * 32767.0); // [2^16 - 1]/2 =
// 32767.0
byteBuffer1[i] = (byte) x; // low byte
byteBuffer1[++i] = (byte) (x >>> 8); // high byte
}
byteBuffer2 = new byte[buffer2.length * 2];
for (int j = 0, bufferIndex = 0; j < byteBuffer2.length; j++) {
y = (short) (buffer2[bufferIndex++] * 32767.0);
byteBuffer2[j] = (byte) y; // low byte
byteBuffer2[++j] = (byte) (y >>> 8); // high byte
}
byteBufferFinal = new byte[byteBuffer1.length * 2];
// LL RR LL RR LL RR
for (int k = 0, index = 0; index < byteBufferFinal.length - 4; k = k + 2) {
byteBufferFinal[index] = byteBuffer1[k]; // LEFT
// {0,1/4,5/8,9/12,13;...}
byteBufferFinal[index + 1] = byteBuffer1[k + 1];
index = index + 2;
byteBufferFinal[index] = byteBuffer2[k]; // RIGHT
// {2,3/6,7/10,11;...}
byteBufferFinal[index + 1] = byteBuffer2[k + 1];
index = index + 2;
}
try {
FileOutputStream ss = new FileOutputStream(Environment.getExternalStorageDirectory().getPath() + "/" + AUDIO_RECORDER_FOLDER + "/source.txt");
ss.write(byteBufferFinal);
ss.flush();
ss.close();
}
catch (IOException ioe){
Log.e("IO Error","Write source error.");
}
}
private void setButtonHandlers() {
((Button) findViewById(R.id.btnStart)).setOnClickListener(startClick);
((Button) findViewById(R.id.btnStop)).setOnClickListener(stopClick);
((Button) findViewById(R.id.btnPlay)).setOnClickListener(playClick);
}
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);
enableButton(R.id.btnPlay, isRecording);
}
private String getFilename() {
String filepath = Environment.getExternalStorageDirectory().getPath();
File file = new File(filepath, AUDIO_RECORDER_FOLDER);
if (!file.exists()) {
file.mkdirs();
}
MediaScannerConnection.scanFile(this, new String[]{filepath}, null, null);
store = file.getAbsolutePath() + "/" + "Audio"
+ AUDIO_RECORDER_FILE_EXT_WAV;
return store;
}
private String getTempFilename() {
String filepath = Environment.getExternalStorageDirectory().getPath();
File file = new File(filepath, AUDIO_RECORDER_FOLDER);
if (!file.exists()) {
file.mkdirs();
}
File tempFile = new File(filepath, AUDIO_RECORDER_TEMP_FILE);
if (tempFile.exists())
tempFile.delete();
return (file.getAbsolutePath() + "/" + AUDIO_RECORDER_TEMP_FILE);
}
private void startRecording() {
//BandPass bandpass = new BandPass(19000,2000,44100);
/* BandPass bandpass = new BandPass(50,2,SAMPLE_RATE);
int [] freqR = {FREQUENCY_RIGHT};
int [] freqL = {FREQUENCY_LEFT};
float[] testL = shortToFloat(freqR);
float [] testR = shortToFloat(freqL);
bandpass.process(testL,testR);
bandpass.printCoeff();
*/
recorder = new AudioRecord(MediaRecorder.AudioSource.CAMCORDER,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, bufferSize);
AudioManager am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
am.setStreamVolume(AudioManager.STREAM_MUSIC, am.getStreamMaxVolume(AudioManager.STREAM_MUSIC), 0);
/*
* AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
* (int) RECORDER_SAMPLERATE,AudioFormat.CHANNEL_OUT_STEREO,
* AudioFormat.ENCODING_PCM_16BIT, bufferSize, AudioTrack.MODE_STREAM);
*/
audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
(int) SAMPLE_RATE, PLAY_CHANNELS,
AudioFormat.ENCODING_PCM_16BIT, byteBufferFinal.length,
AudioTrack.MODE_STATIC);
audioTrack.write(byteBufferFinal, 0, byteBufferFinal.length);
audioTrack.play();
BandPass bandpass = new BandPass(50,2,SAMPLE_RATE);
int [] freqR = {FREQUENCY_RIGHT};
int [] freqL = {FREQUENCY_LEFT};
float[] testL = shortToFloat(freqR);
float [] testR = shortToFloat(freqL);
bandpass.process(testL,testR);
bandpass.printCoeff();
audioTrack.setPlaybackRate(RECORDER_SAMPLERATE);
recorder.startRecording();
isRecording = true;
recordingThread = new Thread(new Runnable() {
@Override
public void run() {
try {
writeAudioDataToFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}, "AudioRecorder Thread");
recordingThread.start();
}
double[][] deinterleaveData(double[] samples, int numChannels) {
// assert(samples.length() % numChannels == 0);
int numFrames = samples.length / numChannels;
double[][] result = new double[numChannels][];
for (int ch = 0; ch < numChannels; ch++) {
result[ch] = new double[numFrames];
for (int i = 0; i < numFrames; i++) {
result[ch][i] = samples[numChannels * i + ch];
}
}
return result;
}
private void writeAudioDataToFile() throws IOException {
int read = 0;
byte data[] = new byte[bufferSize];
String filename = getTempFilename();
FileOutputStream os = null;
FileOutputStream rs = null;
try {
os = new FileOutputStream(filename);
rs = new FileOutputStream(getFilename().split(".wav")[0] + ".txt");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (null != os) {
while (isRecording) {
read = recorder.read(data, 0, bufferSize);
if (AudioRecord.ERROR_INVALID_OPERATION != read) {
try {
os.write(data);
rs.write(data);
} catch (IOException e) {
e.printStackTrace();
}
}
}
try {
os.close();
rs.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void stopRecording() {
if (null != recorder) {
isRecording = false;
audioTrack.flush();
audioTrack.stop();
audioTrack.release();
recorder.stop();
recorder.release();
recorder = null;
recordingThread = null;
}
copyWaveFile(getTempFilename(), getFilename());
deleteTempFile();
MediaScannerConnection.scanFile(this, new String[]{getFilename()}, null, null);
AudioManager am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
am.setStreamVolume(AudioManager.STREAM_MUSIC, 0, 0);
}
private void deleteTempFile() {
File file = new File(getTempFilename());
file.delete();
}
private void copyWaveFile(String inFilename, String outFilename) {
FileInputStream in = null;
FileOutputStream out = null;
long totalAudioLen = 0;
long totalDataLen = totalAudioLen + 36;
long longSampleRate = RECORDER_SAMPLERATE;
int channels = 2;
long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels / 8;
byte[] data = new byte[bufferSize];
try {
in = new FileInputStream(inFilename);
out = new FileOutputStream(outFilename);
totalAudioLen = in.getChannel().size();
totalDataLen = totalAudioLen + 36;
WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
longSampleRate, channels, byteRate);
while (in.read(data) != -1) {
out.write(data);
}
in.close();
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private void playWaveFile() {
String filepath = store;
Log.d("PLAYWAVEFILE", "I AM INSIDE");
// define the buffer size for audio track
int minBufferSize = AudioTrack.getMinBufferSize(8000,
AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT);
int bufferSize = 512;
audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
(int) RECORDER_SAMPLERATE, AudioFormat.CHANNEL_OUT_STEREO,
AudioFormat.ENCODING_PCM_16BIT, minBufferSize,
AudioTrack.MODE_STREAM);
int count = 0;
byte[] data = new byte[bufferSize];
try {
FileInputStream fileInputStream = new FileInputStream(filepath);
DataInputStream dataInputStream = new DataInputStream(
fileInputStream);
audioTrack.play();
Toast.makeText(RecorderActivity.this, "this is my Toast message!!! =)",
Toast.LENGTH_LONG).show();
while ((count = dataInputStream.read(data, 0, bufferSize)) > -1) {
Log.d("PLAYWAVEFILE", "WHILE INSIDE");
audioTrack.write(data, 0, count);
//BandPass bandpass = new BandPass(19000,2000,44100); //Actual
//BandPass bandpass = new BandPass(5000,2000,44100); //Test
//int [] freqR = {FREQUENCY_RIGHT};
//int [] freqL = {FREQUENCY_LEFT};
//float[] testR = shortToFloat(freqR);
//float [] testL = shortToFloat(freqL);
//bandpass.process(testR,testL);
// BandPass bandpass = new BandPass(19000,2000,44100);
//float bw = bandpass.getBandWidth();
//float hello = bandpass.getBandWidth();
//float freq = bandpass.frequency();
//float[] test = {FREQUENCY_RIGHT,FREQUENCY_LEFT};
//shortToFloat(test);
//test [0] = FREQUENCY_RIGHT;
//test [1] = FREQUENCY_LEFT;
//bandpass.process(FREQUENCY_LEFT,FREQUENCY_RIGHT);
//Log.d("MyApp","I am here");
//Log.d("ADebugTag", "Valueeees: " + Float.toString(hello));
//Log.d("Bandwidth: " , "Bandwidth: " + Float.toString(bw));
//Log.d("Frequency: " , "Frequency is " + Float.toString(freq));
//bandpass.setBandWidth(20);
//bandpass.printCoeff();
}
audioTrack.stop();
audioTrack.release();
dataInputStream.close();
fileInputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private void WriteWaveFileHeader(FileOutputStream out, long totalAudioLen,
long totalDataLen, long longSampleRate, int channels, long byteRate)
throws IOException {
byte[] header = new byte[44];
header[0] = 'R'; // RIFF/WAVE header
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte) (totalDataLen & 0xff);
header[5] = (byte) ((totalDataLen >> 8) & 0xff);
header[6] = (byte) ((totalDataLen >> 16) & 0xff);
header[7] = (byte) ((totalDataLen >> 24) & 0xff);
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
header[12] = 'f'; // 'fmt ' chunk
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
header[16] = 16; // 4 bytes: size of 'fmt ' chunk
header[17] = 0;
header[18] = 0;
header[19] = 0;
header[20] = 1; // format = 1
header[21] = 0;
header[22] = (byte) channels;
header[23] = 0;
header[24] = (byte) (longSampleRate & 0xff);
header[25] = (byte) ((longSampleRate >> 8) & 0xff);
header[26] = (byte) ((longSampleRate >> 16) & 0xff);
header[27] = (byte) ((longSampleRate >> 24) & 0xff);
header[28] = (byte) (byteRate & 0xff);
header[29] = (byte) ((byteRate >> 8) & 0xff);
header[30] = (byte) ((byteRate >> 16) & 0xff);
header[31] = (byte) ((byteRate >> 24) & 0xff);
header[32] = (byte) (2 * 16 / 8); // block align
header[33] = 0;
header[34] = RECORDER_BPP; // bits per sample
header[35] = 0;
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte) (totalAudioLen & 0xff);
header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
header[43] = (byte) ((totalAudioLen >> 24) & 0xff);
out.write(header, 0, 44);
}
private View.OnClickListener startClick = new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Thread recordThread = new Thread(new Runnable() {
@Override
public void run() {
isRecording = true;
startRecording();
}
});
recordThread.start();
btnStart.setEnabled(false);
btnStop.setEnabled(true);
btnPlay.setEnabled(false);
}
};
private View.OnClickListener stopClick = new View.OnClickListener() {
@Override
public void onClick(View v) {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
stopRecording();
enableButtons(false);
btnPlay.setEnabled(true);
// stop();
}
}, 100);
}
};
private View.OnClickListener playClick = new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
playWaveFile();
btnPlay.setEnabled(true);
String filepath = store;
final String promptPlayRecord = "PlayWaveFile()\n" + filepath;
SpannableStringBuilder biggerText = new SpannableStringBuilder(promptPlayRecord);
biggerText.setSpan(new RelativeSizeSpan(2.05f), 0, promptPlayRecord.length(), 0);
Toast.makeText(RecorderActivity.this, biggerText, Toast.LENGTH_LONG).show();
}
};
}
The method below is to convert my 16-bit integer to float since the library uses float
/**
* Convert int[] audio to 32 bit float format.
* From [-32768,32768] to [-1,1]
* @param audio
*/
private float[] shortToFloat(int[] audio) {
Log.d("SHORTTOFLOAT","INSIDE SHORTTOFLOAT");
float[] converted = new float[audio.length];
for (int i = 0; i < converted.length; i++) {
// [-32768,32768] -> [-1,1]
converted[i] = audio[i] / 32768f; /* default range for Android PCM audio buffers) */
}
return converted;
}
Trying to implement bandpass filter under "SaveRecording" Method
//BandPass bandpass = new BandPass(19000,2000,44100);
Since I am trying to implement a range of 18k to 20k, I input the above values to the bandpass filter.
BandPass bandpass = new BandPass(50,2,44100); (This is just to test if the frequency has any changes since 18k-20k is not within human range)
int [] freqR = {FREQUENCY_RIGHT};
int [] freqL = {FREQUENCY_LEFT};
float[] testL = shortToFloat(freqR);
float [] testR = shortToFloat(freqL);
bandpass.process(testL,testR);
bandpass.printCoeff();
Since I am recording in STEREO, I am using the
public final synchronized void process(float[] sigLeft, float[] sigRight) {} found in the IIRFilter.java class.
However, I am not hearing any differences even though I implemented the above method. What am I doing wrong? Could anyone advise/help me?
Thank You so much! Terribly new in this signal processing. Any tips/hints on how to progress is much appreciated!!!
Updated
Since I have to output the .wav file with the filtered sound signal, I thought the way to do it is to put the BandPass filter under the "StartRecording" method, however, it is not working. Why is it that I am doing wrong?
private void startRecording() {
int count = 0;
recorder = new AudioRecord(MediaRecorder.AudioSource.CAMCORDER,
RECORDER_SAMPLERATE, RECORDER_CHANNELS,
RECORDER_AUDIO_ENCODING, bufferSize);
AudioManager am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
am.setStreamVolume(AudioManager.STREAM_MUSIC, am.getStreamMaxVolume(AudioManager.STREAM_MUSIC), 0);
audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
(int) SAMPLE_RATE, PLAY_CHANNELS,
AudioFormat.ENCODING_PCM_16BIT, byteBufferFinal.length,
AudioTrack.MODE_STATIC);
BandPass bandpass = new BandPass(19000,2000,44100);
float[][] signals = deinterleaveData(byteToFloat(byteBufferFinal), 2);
bandpass.process(signals[0], signals[1]);
audioTrack.write(interleaveData(signals), 0, count, WRITE_NON_BLOCKING);
audioTrack.play();
//audioTrack.write(byteBufferFinal, 0, byteBufferFinal.length); //Original
audioTrack.setPlaybackRate(RECORDER_SAMPLERATE);
recorder.startRecording();
isRecording = true;
recordingThread = new Thread(new Runnable() {
@Override
public void run() {
try {
writeAudioDataToFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}, "AudioRecorder Thread");
recordingThread.start();
}
Updated (14 March 2016) This is the image of the output .wav file shown by Audacity:
May I ask if it is considered filtered? What are the characteristics that I should look out for to ensure that it is filtered correctly.
The above image produce by press the black triangle
The above image graph produced by the Analyse->Plot Specturm
What about this graph? Does it implement the bandpass filter successfully? Thank
There is an issue with how you interface with the Bandpass.java source, probably resulting from what appears to be a bit of a misconception: IIR filters do not process frequencies, but they rather process time-domain data samples (which may exhibit oscillatory behavior).
As such you have to provide those time domain samples as inputs to Bandpass.process(). Since you are reading raw bytes from file, you will need to convert those bytes to float. You could do this with:
/**
* Convert byte[] raw audio to 16 bit int format.
* @param rawdata
*/
private int[] byteToShort(byte[] rawdata) {
int[] converted = new int[rawdata.length / 2];
for (int i = 0; i < converted.length; i++) {
// Wave file data are stored in little-endian order
int lo = rawdata[2*i];
int hi = rawdata[2*i+1];
converted[i] = ((hi&0xFF)<<8) | (lo&0xFF);
}
return converted;
}
private float[] byteToFloat(byte[] audio) {
return shortToFloat(byteToShort(audio));
}
Also for stereo wave files, you will get samples from the wave files which are interleaved. So you will also need to deinterleave the samples. This can be achieved in a similar fashion as you've done with deinterleaveData, except you will need a variant converting to float[][] instead of to double[][] since Bandpass.process expects float arrays.
You will of course also need to recombine the two channels back together after the filtering but before feeding the resulting filtered signals back to the audioTrack:
float[] interleaveData(float[][] data) {
int numChannels = data.length;
int numFrames = data[0].length;
float[] result = new float[numFrames*numChannels];
for (int i = 0; i < numFrames; i++) {
for (int ch = 0; ch < numChannels; ch++) {
result[numChannels * i + ch] = data[ch][i];
}
}
return result;
}
You should now have the required building blocks to filter your audio:
BandPass bandpass = new BandPass(19000,2000,44100);
while ((count = dataInputStream.read(data, 0, bufferSize)) > -1) {
// decode and deinterleave stereo 16-bit per sample data
float[][] signals = deinterleaveData(byteToFloat(data), 2);
// filter data samples, updating the buffers with the filtered samples.
bandpass.process(signals[0], signals[1]);
// recombine signals for playback
audioTrack.write(interleaveData(signals), 0, count, WRITE_NON_BLOCKING);
}
P.S.: as a final note, you are currently reading all the wave file as data samples, header included. This will result in a short noisy burst at the beginning. To avoid this, you should skip the header.