Implementare getMaxAmplitude per audioRecord

Question

Sto usando audioRecord invece di mediarecorder nella mia app funziona bene ma ho una logica che dipende molto dalla maxamplitude che è davvero difficile da ottenere usando l'audiorecord qui è quello che sto usando durante la lettura del 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&&amplitude<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(); 
      } 
     } 
    } 

, ma questo non funziona per me come il valore cambia in fretta che ho bisogno di implementare qualcosa di simile getMaxAmplitude() per audioRecord.

Answer 1

Questo non fa ciò che si vuole e più ... quindi emette i punti massimi a un file che è leggibile in Excel. (Stavo per risolvere questo problema me stesso, quindi il tempismo è fortuita.)

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; 
    } 

} 

Answer 2

int amplitude = (buffer[0] & 0xff) << 8 | buffer[1]; 
amplitude = Math.abs(ab); 

Hai commesso un errore qui? Penso che dovrebbe essere

int ab = (buffer[0] & 0xff) << 8 | buffer[1]; 
int amplitude = Math.abs(ab); 

Answer 3

Se la codifica è ENCODING_PCM_16BIT, quindi si dovrebbe usare

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)); 
} 

Per ulteriori informazioni, dare un'occhiata a How to record voice in "wav" format in Android