java - 音频:更改字节数组中样本的音量

Question

我正在使用 this method (shown below) 将 wav 文件读入字节数组.现在我已将它存储在我的字节数组中，我想更改音量。

private byte[] getAudioFileData(final String filePath) {
    byte[] data = null;
    try {
    final ByteArrayOutputStream baout = new ByteArrayOutputStream();
    final File file = new File(filePath);
    final AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(file);

    byte[] buffer = new byte[4096];
    int c;
    while ((c = audioInputStream.read(buffer, 0, buffer.length)) != -1) {
        baout.write(buffer, 0, c);
    }
    audioInputStream.close();
    baout.close();
    data = baout.toByteArray();
    } catch (Exception e) {
    e.printStackTrace();
    }
    return data;
}

编辑:根据请求提供一些关于音频格式的信息:

PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian

在物理课上我记得你可以通过将正弦值乘以 0 到 1 之间的数字来改变正弦波的振幅。

编辑:16 位示例的更新代码:

private byte[] adjustVolume(byte[] audioSamples, double volume) {
    byte[] array = new byte[audioSamples.length];
    for (int i = 0; i < array.length; i+=2) {
        // convert byte pair to int
        int audioSample = (int) ((audioSamples[i+1] & 0xff) << 8) | (audioSamples[i] & 0xff);

        audioSample = (int) (audioSample * volume);

        // convert back
        array[i] = (byte) audioSample;
        array[i+1] = (byte) (audioSample >> 8);

    }
    return array;
}

如果我将 audioSample 与 volume 相乘，声音会严重失真。如果我不这样做并将两个数组与 Arrays.compare(array, audioSample) 进行比较，我可以得出结论，字节数组正在正确转换为 int，反之亦然。

有人能帮帮我吗？我在这里弄错了什么？谢谢! :)

Answer 1

int类型的问题，java中int的大小为4字节，样本大小为2字节

这个有效的代码:

private byte[] adjustVolume(byte[] audioSamples, float volume) {
        byte[] array = new byte[audioSamples.length];
        for (int i = 0; i < array.length; i+=2) {
            // convert byte pair to int
            short buf1 = audioSamples[i+1];
            short buf2 = audioSamples[i];

            buf1 = (short) ((buf1 & 0xff) << 8);
            buf2 = (short) (buf2 & 0xff);

            short res= (short) (buf1 | buf2);
            res = (short) (res * volume);

            // convert back
            array[i] = (byte) res;
            array[i+1] = (byte) (res >> 8);

        }
        return array;
}