绘制音频波形图Java

Question

我想从.wav音频文件绘制波形图。我在这个网站发现，提取一个.wav的字节的函数：

ByteArrayOutputStream out = new ByteArrayOutputStream(); 
BufferedInputStream in = null; 
try { 
    in = new BufferedInputStream(new FileInputStream(args[0])); 
} catch (FileNotFoundException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
} 

int read; 
byte[] buff = new byte[1024]; 
while ((read = in.read(buff)) > 0) 
{ 
    out.write(buff, 0, read); 
} 
out.flush(); 

byte[] audioBytes = out.toByteArray(); 
for (int i=0; i<audioBytes.length; i++) { 
    System.out.println(audioBytes[i]); 
} 

然后我用我在控制台中发现的点（的System.out ...）绘制的“Microsoft Excel中”我的音频波形和risult是：

waveform on Excel 但我的.wav文件的这种波形是从波形有很大不同的是地块（即）开源“普瑞特”：

waveform on Praat 我哪里错了？不是我必须拿的文件的字节数？

Answer 1

在阵“结果”有，你会发现点

public double[] extract(File inputFile) { 
     AudioInputStream in = null; 
     try { 
      in = AudioSystem.getAudioInputStream(inputFile); 
     } catch (Exception e) { 
      System.out.println("Cannot read audio file"); 
      return new double[0]; 
     } 
     AudioFormat format = in.getFormat(); 
     byte[] audioBytes = readBytes(in); 

     int[] result = null; 
     if (format.getSampleSizeInBits() == 16) { 
      int samplesLength = audioBytes.length/2; 
      result = new int[samplesLength]; 
      if (format.isBigEndian()) { 
       for (int i = 0; i < samplesLength; ++i) { 
        byte MSB = audioBytes[i * 2]; 
        byte LSB = audioBytes[i * 2 + 1]; 
        result[i] = MSB << 8 | (255 & LSB); 
       } 
      } else { 
       for (int i = 0; i < samplesLength; i += 2) { 
        byte LSB = audioBytes[i * 2]; 
        byte MSB = audioBytes[i * 2 + 1]; 
        result[i/2] = MSB << 8 | (255 & LSB); 
       } 
      } 
     } else { 
      int samplesLength = audioBytes.length; 
      result = new int[samplesLength]; 
      if (format.getEncoding().toString().startsWith("PCM_SIGN")) { 
       for (int i = 0; i < samplesLength; ++i) { 
        result[i] = audioBytes[i]; 
       } 
      } else { 
       for (int i = 0; i < samplesLength; ++i) { 
        result[i] = audioBytes[i] - 128; 
       } 
      } 
     } 

     return result; 
    } 

Answer 2

看来你假设文件中的每个字节都代表了下一个时间点波形的幅度。这（一般来说）不是这种情况。除了文件以标题开始的事实之外，每个样本由多个通道组成，并且在每个通道内，样本可能会占用较少的空间（例如，4位或更多（例如16位））空间，而不仅仅是一个字节。例如这样的解释：http://www.topherlee.com/software/pcm-tut-wavformat.html