轉載-java將pcm音頻轉換成wav格式

原文鏈接：https://blog.csdn.net/qq_25925973/article/details/90441386

PCM（Pulse Code Modulation）脈衝編碼調製是數字通信的編碼方式之一。主要過程是將話音、圖像等模擬信號每隔一定時間進行取樣，使其離散化，同時將抽樣值按分層單位四捨五入取整量化，同時將抽樣值按一組二進制碼來表示抽樣脈衝的幅值。

pcm音頻想要直接聽需要專業的軟件纔可以，這裏我需要把pcm的音頻轉化爲wav這種無損的格式，也就是需要在pcm文件添加wav的音頻頭，這樣就可以直接使用音頻軟件打開了。使用Java實現的方式見下文

 

 1 package com.test.shell;
 2 
 3 import java.io.*;
 4 import com.alibaba.druid.util.StringUtils;
 5 
 6 public class ShellUtils {
 7     public static File tranPcmToWavFile(File pcmFile) {
 8         FileInputStream fis = null;
 9         FileOutputStream fos = null;
10         try {
11             fis = new FileInputStream(pcmFile);
12             String wavfilepath = pcmFile.getAbsolutePath().substring(0, pcmFile.getAbsolutePath().lastIndexOf(".")) + "." + SysConstants.IVR_SPEAK_TYPE_WAV.toLowerCase();
13 
14 
15             File file = new File(wavfilepath);
16             if (!file.exists()) {
17                 file.createNewFile();
18             }
19             fos = new FileOutputStream(wavfilepath);
20 
21 
22             int PCMSize = 0;
23             byte[] buf = new byte[1024 * 4];
24             int size = fis.read(buf);
25 
26             while (size != -1) {
27                 PCMSize += size;
28                 size = fis.read(buf);
29             }
30             fis.close();
31 
32             //填入參數，比特率等等。這裏用的是16位單聲道 8000 hz
33 
34             WaveHeader header = new WaveHeader();
35             //長度字段 = 內容的大小（PCMSize) + 頭部字段的大小(不包括前面4字節的標識符RIFF以及fileLength本身的4字節)
36             header.fileLength = PCMSize + (44 - 8);
37             header.FmtHdrLeth = 16;
38             header.BitsPerSample = 16;
39             header.Channels = 1;
40             header.FormatTag = 0x0001;
41             header.SamplesPerSec = 8000;
42             header.BlockAlign = (short) (header.Channels * header.BitsPerSample / 8);
43             header.AvgBytesPerSec = header.BlockAlign * header.SamplesPerSec;
44             header.DataHdrLeth = PCMSize;
45 
46             byte[] h = header.getHeader();
47 
48             assert h.length == 44; //WAV標準，頭部應該是44字節
49             //write header
50             fos.write(h, 0, h.length);
51             //write data stream
52             fis = new FileInputStream(pcmFile);
53             size = fis.read(buf);
54             while (size != -1) {
55                 fos.write(buf, 0, size);
56                 size = fis.read(buf);
57             }
58             fis.close();
59             fos.close();
60             return new File(wavfilepath);
61         } catch (Exception e) {
62             e.printStackTrace();
63         } finally {
64             if (fis != null) {
65                 try {
66                     fis.close();
67                 } catch (IOException e) {
68                     e.printStackTrace();
69                 }
70             }
71             if (fos != null) {
72                 try {
73                     fos.close();
74                 } catch (IOException e) {
75                     e.printStackTrace();
76                 }
77             }
78         }
79         return null;
80     }
81 }

2、其中用到的WaveHeader 如下：

package com.test.shell;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class WaveHeader {

    public final char fileID[] = {'R', 'I', 'F', 'F'};
    public int fileLength;
    public char wavTag[] = {'W', 'A', 'V', 'E'};;
    public char FmtHdrID[] = {'f', 'm', 't', ' '};
    public int FmtHdrLeth;
    public short FormatTag;
    public short Channels;
    public int SamplesPerSec;
    public int AvgBytesPerSec;
    public short BlockAlign;
    public short BitsPerSample;
    public char DataHdrID[] = {'d','a','t','a'};
    public int DataHdrLeth;

    public byte[] getHeader() throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        WriteChar(bos, fileID);
        WriteInt(bos, fileLength);
        WriteChar(bos, wavTag);
        WriteChar(bos, FmtHdrID);
        WriteInt(bos,FmtHdrLeth);
        WriteShort(bos,FormatTag);
        WriteShort(bos,Channels);
        WriteInt(bos,SamplesPerSec);
        WriteInt(bos,AvgBytesPerSec);
        WriteShort(bos,BlockAlign);
        WriteShort(bos,BitsPerSample);
        WriteChar(bos,DataHdrID);
        WriteInt(bos,DataHdrLeth);
        bos.flush();
        byte[] r = bos.toByteArray();
        bos.close();
        return r;
    }

    private void WriteShort(ByteArrayOutputStream bos, int s) throws IOException {
        byte[] mybyte = new byte[2];
        mybyte[1] =(byte)( (s << 16) >> 24 );
        mybyte[0] =(byte)( (s << 24) >> 24 );
        bos.write(mybyte);
    }


    private void WriteInt(ByteArrayOutputStream bos, int n) throws IOException {
        byte[] buf = new byte[4];
        buf[3] =(byte)( n >> 24 );
        buf[2] =(byte)( (n << 8) >> 24 );
        buf[1] =(byte)( (n << 16) >> 24 );
        buf[0] =(byte)( (n << 24) >> 24 );
        bos.write(buf);
    }

    private void WriteChar(ByteArrayOutputStream bos, char[] id) {
        for (int i=0; i<id.length; i++) {
            char c = id[i];
            bos.write(c);
        }
    }
}