问题
I am using audioRecord instead of mediarecorder in my app it's working fine but I have a logic that depends highly on the maxamplitude which is really hard to obtain using the audiorecord here is what I am using when reading the buffer
private void writeAudioDataToFile(){
byte data[] = new byte[bufferSize];
String filename = getTempFilename();
FileOutputStream os = null;
try {
os = new FileOutputStream(filename);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int read = 0;
max=0;
if(null != os){
while(isRecording){
read = recorder.read(buffer, 0, bufferSize);
int ab = (buffer[0] & 0xff) << 8 | buffer[1];
amplitude = Math.abs(ab);
if(amplitude>0&&litude<25000)
isSilence=true;
else
isSilence=false;
//System.out.println(">>>>>>>>>>>"+amplitude);
if(AudioRecord.ERROR_INVALID_OPERATION != read){
try {
os.write(buffer);
} catch (IOException e) {
e.printStackTrace();
}
}
}
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
but this doesn't work for me as the value changes real fast I need to implement something like getMaxAmplitude() for audioRecord.
回答1:
This does what you want and more... then it outputs the max points to a file which is readable in excel. (I was solving this problem myself, so timing is fortuitous.)
package com.example.audiorecord;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
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.Menu;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
private static final int RECORDER_SAMPLERATE = 44100;
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;
private String floatString = "";
Calendar c = Calendar.getInstance();
SimpleDateFormat df = new SimpleDateFormat("ddMMMyyyy_HHmmss");
String formattedDate = df.format(c.getTime());
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_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() {
final File logFile = new File("sdcard/log_"+formattedDate+".txt");
if (!logFile.exists())
{
try
{
logFile.createNewFile();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
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(logFile);
}
}, "AudioRecorder Thread");
recordingThread.start();
}
private void writeAudioDataToFile(File logFile) {
// Write the output audio in byte
short sData[] = new short[BufferElements2Rec];
while (isRecording) {
// gets the voice output from microphone to byte format
recorder.read(sData, 0, BufferElements2Rec);
String sDataString = "";
double sDataMax = 0;
for(int i=0; i<sData.length; i++){
if(Math.abs(sData[i])>=sDataMax){sDataMax=Math.abs(sData[i]);};
sDataString += "\n" + sDataMax;
}
try
{
//BufferedWriter for performance, true to set append to file flag
BufferedWriter buf = new BufferedWriter(new FileWriter(logFile, true));
buf.append(sDataString);
buf.newLine();
buf.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
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;
}
}
}
};
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
finish();
}
return super.onKeyDown(keyCode, event);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
回答2:
int amplitude = (buffer[0] & 0xff) << 8 | buffer[1];
amplitude = Math.abs(ab);
Do you make a mistake here? I think it should be
int ab = (buffer[0] & 0xff) << 8 | buffer[1];
int amplitude = Math.abs(ab);
回答3:
If your encoding is ENCODING_PCM_16BIT , Then you should use
private int cAmplitude= 0;
while(isRecording) {
read = recorder.read(data, 0, bufferSize);
for (int i=0; i<read/2; i++) {
short curSample = getShort(data[i*2], data[i*2+1]);
if (curSample > cAmplitude) {
cAmplitude = curSample;
}
}
Log.d("amplitude",Integer.toString(cAmplitude));
cAmplitude = 0;
}
private short getShort(byte argB1, byte argB2) {
return (short)(argB1 | (argB2 << 8));
}
For more info, have a look at How to record voice in "wav" format in Android
来源：https://stackoverflow.com/questions/11700149/implement-getmaxamplitude-for-audiorecord