【JAVA工作笔记之音频处理】PCM转WAV

最新推荐文章于 2024-06-22 14:08:45 发布

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# PCM转WAV #JAVA #音频处理

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本文提供了一段Java代码，用于将PCM音频文件转换为WAV格式。代码详细展示了如何计算音频长度，设置WAV头信息，如比特率、通道数、采样频率等，并将PCM数据写入新的WAV文件中。

wav头长度44字节

增加wav头文件信息

package com.example.demo;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class PcmToWavUtil {
    public static void pcmToWav(String fileName) throws IOException {
        String src = fileName ;
        FileInputStream fis = new FileInputStream(src);
        fileName = fileName.substring(fileName.length()-3,fileName.length())+"wav";
        FileOutputStream fos = new FileOutputStream(fileName);

        //计算长度
        int PCMSize = 0;
        byte[] buf = new byte[1024 * 4];
        int size = fis.read(buf);

        while (size != -1) {
            PCMSize += size;
            size = fis.read(buf);
        }
        fis.close();

        //填入参数，比特率等等。这里用的是16位单声道 8000 hz
        WaveHeader header = new WaveHeader();
        //长度字段 = 内容的大小（PCMSize) + 头部字段的大小(不包括前面4字节的标识符RIFF以及fileLength本身的4字节)
        header.fileLength = PCMSize + (44 - 8);
        header.FmtHdrLeth = 16;
        header.BitsPerSample = 16;
        header.Channels = 1;
        header.FormatTag = 0x0001;
        header.SamplesPerSec = 8000;
        header.BlockAlign = (short) (header.Channels * header.BitsPerSample / 8);
        header.AvgBytesPerSec = header.BlockAlign * header.SamplesPerSec;
        header.DataHdrLeth = PCMSize;

        byte[] h = header.getHeader();

        assert h.length == 44; //WAV标准，头部应该是44字节
        //write header
        fos.write(h, 0, h.length);
        //write data stream
        fis = new FileInputStream(src);
        size = fis.read(buf);
        while (size != -1) {
            fos.write(buf, 0, size);
            size = fis.read(buf);
        }
        fis.close();
        fos.close();
        System.out.println("Convert OK!");
    }

    static 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);
            }
        }
}
}