用java写一个replaygain的过滤器

好的，以下是一个简单的Java实现ReplayGain过滤器的示例代码：

import java.io.*;
import javax.sound.sampled.*;

public class ReplayGainFilter {

    public static void main(String[] args) {
        if (args.length != 2) {
            System.out.println("Usage: java ReplayGainFilter <input file> <output file>");
            return;
        }

        try {
            AudioInputStream in = AudioSystem.getAudioInputStream(new File(args[0]));
            AudioFormat format = in.getFormat();
            AudioInputStream din = AudioSystem.getAudioInputStream(format, in);
            double gain = calculateReplayGain(din);
            din = AudioSystem.getAudioInputStream(new File(args[0]));
            AudioInputStream dout = new AudioInputStream(new GainFilterStream(din, gain), format, din.getFrameLength());
            AudioSystem.write(dout, AudioFileFormat.Type.WAVE, new File(args[1]));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static double calculateReplayGain(AudioInputStream in) throws IOException {
        byte[] buffer = new byte[4096];
        int n = 0;
        double sum = 0.0;
        while (n != -1) {
            n = in.read(buffer);
            if (n > 0) {
                for (int i = 0; i < n; i += 2) {
                    short sample = (short) ((buffer[i + 1] << 8) | buffer[i]);
                    sum += sample * sample;
                }
            }
        }
        double rms = Math.sqrt(sum / (in.getFrameLength() * format.getChannels()));
        double gain = 20.0 * Math.log10(1.0 / rms);
        return gain;
    }

    private static class GainFilterStream extends FilterInputStream {
        private double gain;

        public GainFilterStream(InputStream in, double gain) {
            super(in);
            this.gain = gain;
        }

        public int read(byte[] b, int off, int len) throws IOException {
            int n = super.read(b, off, len);
            if (n > 0) {
                for (int i = off; i < off + n; i += 2) {
                    short sample = (short) ((b[i + 1] << 8) | b[i]);
                    sample = (short) (sample * Math.pow(10.0, gain / 20.0));
                    b[i + 1] = (byte) (sample >> 8);
                    b[i] = (byte) (sample & 0xff);
                }
            }
            return n;
        }
    }
}

这个程序使用Java的音频API来读取输入文件，并计算出ReplayGain值。然后，它使用一个自定义的FilterInputStream来应用增益，并将结果写入输出文件。