想写一个将双声道的 wav 转成 单声道的 wav，生成的却是噪音，不知哪里错了。

[幽饮烛]

package test;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class Test1
{
    public static void main(String[] args) throws Exception
    {
        File file = new File("T:\\temp\\tada.wav").getAbsoluteFile();
        System.out.println(file.getName());
        BufferedInputStream input = new BufferedInputStream(new FileInputStream(file));
        RIFFHeader riff = new RIFFHeader(input);
        System.out.println(riff.getID());
        System.out.println(riff.getSize());
        System.out.println(riff.getFormat());
        WAVEHeader wave = new WAVEHeader(input);
        System.out.println(wave.getID());
        System.out.println(wave.getSize());
        System.out.println(wave.getFormatTag());
        System.out.println(wave.getChannels());
        System.out.println(wave.getSamplesPerSec());
        System.out.println(wave.getAvgBytesPerSec());
        System.out.println(wave.getBlockAlign());
        System.out.println(wave.getBitsPerSample());
        System.out.println(wave.getOther());
        DataHeader data = new DataHeader(input);
        System.out.println(data.getID());
        System.out.println(data.getSize());
        BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(new File(file.getParentFile(), file.getName() + ".out")));
        writeString(output, riff.getID());
        writeInteger(output, 4, data.getSize() / wave.getChannels() + 8 + wave.getSize() + 8 + 4);
        writeString(output, riff.getFormat());
        writeString(output, wave.getID());
        writeInteger(output, 4, wave.getSize());
        writeInteger(output, 2, wave.getFormatTag());
        writeInteger(output, 2, 1);
        writeInteger(output, 4, wave.getSamplesPerSec());
        writeInteger(output, 4, wave.getAvgBytesPerSec() / wave.getChannels());
        writeInteger(output, 2, wave.getBlockAlign() / wave.getChannels());
        writeInteger(output, 2, wave.getBitsPerSample());
        if (wave.getSize() != 16)
        {
            writeString(output, wave.getOther());
        }
        writeString(output, data.getID());
        writeInteger(output, 4, data.getSize() / wave.getChannels());
        int byteCount = wave.getBitsPerSample() / 8;
        int frameCount = data.getSize() / wave.getChannels() / byteCount;
        int[] frames = new int[wave.getChannels()];
        int frame;
        for (int i = 0; i < frameCount; i++)
        {
            for (int f = 0; f < frames.length; f++)
            {
                frame = 0;
                for (int d = 0; d < byteCount; d++)
                {
                    frame += input.read() << (d * 8);
                }
                frames[f] = frame;
            }
            frame = 0;
            for (int f : frames)
            {
                frame += f;
            }
            frame /= frames.length;
            writeInteger(output, byteCount, frame);
        }
        input.close();
        output.close();
    }

    private static void writeInteger(final OutputStream stream, final int size, final int value) throws IOException
    {
        for (int i = 0; i < size; i++)
        {
            stream.write((value >>> (i * 8)) & 0xFF);
        }
    }

    public static void writeString(final OutputStream stream, final String string) throws IOException
    {
        char[] chars = string.toCharArray();
        for (char c : chars)
        {
            stream.write(c);
        }
    }

    public static class DataHeader
    {
        private final String id;
        private final int size;

        public String getID()
        {
            return id;
        }

        public int getSize()
        {
            return size;
        }

        public DataHeader(final InputStream stream) throws Exception
        {
            byte[] buffer = new byte[4];
            stream.read(buffer);
            char[] chars = new char[buffer.length];
            for (int i = 0; i < chars.length; i++)
            {
                chars[i] = (char) buffer[i];
            }
            id = new String(chars);
            size = (stream.read() & 255) + ((stream.read() & 255) << 8) + ((stream.read() & 255) << 16) + ((stream.read() & 255) << 24);
        }
    }

    public static class WAVEHeader
    {
        private final String id;
        private final int size;
        private final int formatTag;
        private final int channels;
        private final int samplesPerSec;
        private final int avgBytesPerSec;
        private final int blockAlign;
        private final int bitsPerSample;
        private final String other;

        public int getBlockAlign()
        {
            return blockAlign;
        }

        public int getBitsPerSample()
        {
            return bitsPerSample;
        }

        public String getOther()
        {
            return other;
        }

        public int getSize()
        {
            return size;
        }

        public int getFormatTag()
        {
            return formatTag;
        }

        public int getChannels()
        {
            return channels;
        }

        public int getSamplesPerSec()
        {
            return samplesPerSec;
        }

        public int getAvgBytesPerSec()
        {
            return avgBytesPerSec;
        }

        public String getID()
        {
            return id;
        }

        public WAVEHeader(final InputStream stream) throws Exception
        {
            byte[] buffer = new byte[4];
            stream.read(buffer);
            char[] chars = new char[buffer.length];
            for (int i = 0; i < chars.length; i++)
            {
                chars[i] = (char) buffer[i];
            }
            id = new String(chars);
            size = (stream.read() & 255) + ((stream.read() & 255) << 8) + ((stream.read() & 255) << 16) + ((stream.read() & 255) << 24);
            formatTag = (stream.read() & 255) + ((stream.read() & 255) << 8);
            channels = (stream.read() & 255) + ((stream.read() & 255) << 8);
            samplesPerSec = (stream.read() & 255) + ((stream.read() & 255) << 8) + ((stream.read() & 255) << 16) + ((stream.read() & 255) << 24);
            avgBytesPerSec = (stream.read() & 255) + ((stream.read() & 255) << 8) + ((stream.read() & 255) << 16) + ((stream.read() & 255) << 24);
            blockAlign = (stream.read() & 255) + ((stream.read() & 255) << 8);
            bitsPerSample = (stream.read() & 255) + ((stream.read() & 255) << 8);
            if (size == 16)
            {
                other = "";
            }
            else
            {
                buffer = new byte[size - 16];
                stream.read(buffer);
                chars = new char[buffer.length];
                for (int i = 0; i < chars.length; i++)
                {
                    chars[i] = (char) buffer[i];
                }
                other = new String(chars);
            }
        }
    }

    public static class RIFFHeader
    {
        private final String id;
        private final int size;
        private final String format;

        public String getID()
        {
            return id;
        }

        public int getSize()
        {
            return size;
        }

        public String getFormat()
        {
            return format;
        }

        public RIFFHeader(final InputStream stream) throws Exception
        {
            byte[] buffer = new byte[4];
            stream.read(buffer);
            char[] chars = new char[buffer.length];
            for (int i = 0; i < chars.length; i++)
            {
                chars[i] = (char) buffer[i];
            }
            id = new String(chars);
            size = (stream.read() & 255) + ((stream.read() & 255) << 8) + ((stream.read() & 255) << 16) + ((stream.read() & 255) << 24);
            stream.read(buffer);
            for (int i = 0; i < chars.length; i++)
            {
                chars[i] = (char) buffer[i];
            }
            format = new String(chars);
        }
    }
}

[Michaelbest1]

还没接触过用Java处理音频的。学习

[jiakai0419]

帮你顶一下帖子。
我也没接触过。

[kouyiSC]

哎。以前接触呼叫中心的时候，，wav语音文件都是通过工具转换的。。。没有去注意。。。只能帮你顶了。。。。

[lfp001]

路过，你算是问着了。说说WAV文件中PCM数据的存储格式吧。

16位PCM，每一个样本2字节。立体声的PCM数据左右声道交替存储，用L表示左声道的一个PCM样本，R表示右声道的一个PCM样本，PCM数据在WAV文件中的存放序列是这样的：LRLRLRLR……

16位PCM样本用2字节表示一个值域为-32768至32767的一个样本，这2字节表示的16位整数可能是大头在上，也可能是小头在上。

将这段代码：

int frameCount = data.getSize() / wave.getChannels() / byteCount;
        int[] frames = new int[wave.getChannels()];
        int frame;
        for (int i = 0; i < frameCount; i++)
        {
            for (int f = 0; f < frames.length; f++)
            {
                frame = 0;
                for (int d = 0; d < byteCount; d++)
                {
                    frame += input.read() << (d * 8);
                }
                frames[f] = frame;
            }
            frame = 0;
            for (int f : frames)
            {
                frame += f;
            }
            frame /= frames.length;
            writeInteger(output, byteCount, frame);
        }

改为：

int frameCount = data.getSize() / wave.getChannels() / byteCount;
        int frame;
        byte[] b = new byte[wave.getBitsPerSample() / 4];
        for (int i = 0; i < frameCount; i++)
        {
        	input.read(b); //读入4字节
        	frame = (((b[1] << 8) | (b[0] & 0xff))
					+ (b[3] << 8) | (b[2] & 0xff)) >> 1;
            writeInteger(output, byteCount, frame);
        }

就可以将立体声的WAV文件中的PCM改为16位的单声道的PCM了。我没有测试，应该没得错吧。

[幽饮烛]

        int frame;
        for (int i = 0; i < frameCount; i++)
        {
            for (int f = 0; f < frames.length; f++)
            {
                frame = 0;
                for (int d = 0; d < byteCount; d++)
                {
                    frame += input.read() << (d * 8);
                }
                frames[f] = frame;
            }
            frame = 0;
            for (int f : frames)
            {
                frame += f;
            }
            frame /= frames.length;
            writeInteger(output, byteCount, frame);
        }

改为

        int frame;
        byte[] bytes = new byte[byteCount];
        for (int i = 0; i < frameCount; i++)
        {
            for (int f = 0; f < frames.length; f++)
            {
                input.read(bytes);
                frame = bytes[0] & 255;
                for (int b = 1; b < bytes.length; b++)
                {
                    frame += bytes[b] << (b * 8);
                }
                frames[f] = frame;
            }
            frame = 0;
            for (int f : frames)
            {
                frame += f;
            }
            frame /= frames.length;
            writeInteger(output, byteCount, frame);
        }

就可以了，
大概已经知道原因了，还得去学位操作才行啊。

[Richelprince]

这个要好好学！

[Richelprince]

大侠！！能不能给出这些代码的注释呢？谢谢了！感激不尽！！！

[zhangbole725]

很好很好~~~~~~~~~~~

[gaosunqiong]

大侠，你是怎样将立体声PCM数据转换为单声道立体声的？说一下原理咯？