Android pcm轉(zhuǎn)wav格式方法

更新時間：2017年12月19日 11:19:36 投稿：laozhang

本篇文章主要給大家講述了在Android開發(fā)中將pcm格式轉(zhuǎn)wav格式的方法和代碼實例，需要的朋友跟著學習下吧。

程序中的錄音文件之前直接保存的是 .pcm格式，一直也相安無事，用的挺好。最近有一個webview中需要加載錄音文件，出現(xiàn)了不兼容的問題，所以需要把 .pcm格式文件轉(zhuǎn)換為 .wav格式。

PCM

PCM（Pulse Code Modulation----脈碼調(diào)制錄音)。所謂PCM錄音就是將聲音等模擬信號變成符號化的脈沖列，再予以記錄。PCM信號是由[1]、[0]等符號構(gòu)成的數(shù)字信號，而未經(jīng)過任何編碼和壓縮處理。與模擬信號比，它不易受傳送系統(tǒng)的雜波及失真的影響。動態(tài)范圍寬，可得到音質(zhì)相當好的效果。簡單的說，pcm就是沒有壓縮的音頻格式。

wav

wav全稱是WAVE，.wav是其擴展名，它是一種無損的音頻文件格式，WAV符合 RIFF(Resource Interchange File Format)規(guī)范。所有的WAV都有一個文件頭，這個文件頭是音頻流的編碼參數(shù)。WAV對音頻流的編碼沒有硬性規(guī)定，除了PCM之外，還有幾乎所有支持ACM規(guī)范的編碼都可以為WAV的音頻流進行編碼。

pcm和wav關(guān)系 pcm是無損wav文件中音頻數(shù)據(jù)的一種編碼方式，pcm加上wav文件頭就可以轉(zhuǎn)為wav格式，但wav還可以用其它方式編碼。

PcmToWavUtil

package com.hgb.mytest;
import android.media.AudioFormat;
import android.media.AudioRecord;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * Created by HaoGuibao
 * Date 2016/8/26.
 * Description :pcm格式的音頻轉(zhuǎn)換為wav格式的工具類
 */
public class PcmToWavUtil {
 private int mBufferSize; //緩存的音頻大小
 private int mSampleRate = 8000;// 8000|16000
 private int mChannel = AudioFormat.CHANNEL_IN_STEREO; //立體聲
 private int mEncoding = AudioFormat.ENCODING_PCM_16BIT;

 public PcmToWavUtil() {
  this.mBufferSize = AudioRecord.getMinBufferSize(mSampleRate, mChannel, mEncoding);
 }
 /**
  * @param sampleRate sample rate、采樣率
  * @param channel channel、聲道
  * @param encoding Audio data format、音頻格式
  */
 public PcmToWavUtil(int sampleRate, int channel, int encoding) {
  this.mSampleRate = sampleRate;
  this.mChannel = channel;
  this.mEncoding = encoding;
  this.mBufferSize = AudioRecord.getMinBufferSize(mSampleRate, mChannel, mEncoding);
 }
 /**
  * pcm文件轉(zhuǎn)wav文件
  *
  * @param inFilename 源文件路徑
  * @param outFilename 目標文件路徑
  */
 public void pcmToWav(String inFilename, String outFilename) {
  FileInputStream in;
  FileOutputStream out;
  long totalAudioLen;
  long totalDataLen;
  long longSampleRate = mSampleRate;
  int channels = 2;
  long byteRate = 16 * mSampleRate * channels / 8;
  byte[] data = new byte[mBufferSize];
  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 (IOException e) {
   e.printStackTrace();
  }
 }
 /**
  * 加入wav文件頭
  */
 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'; //WAVE
  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] = 16; // bits per sample
  header[35] = 0;
  header[36] = 'd'; //data
  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);
 }
}

Demo 把手機內(nèi)存卡上 /sdcard/yxck/treamentRecord/ 的123.pcm轉(zhuǎn)換為123.wav文件。

public class MainActivity extends AppCompatActivity {
 /**
  * pcm格式轉(zhuǎn)wav格式工具類
  */
 private PcmToWavUtil pcmToWavUtil = new PcmToWavUtil();

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  final String path = "/sdcard/yxck/treamentRecord/123.pcm";
  //按原路徑把音頻文件后綴改一下;
  final String outpath = path.replace(".pcm", ".wav");

  Button button = (Button) findViewById(R.id.button);
  button.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View view) {
    pcmToWavUtil.pcmToWav(path, outpath);
   }
  });
 }
}

pcm轉(zhuǎn)換wav格式成功