音频：在字节数组的样本量变化 [英] Audio: Change Volume of samples in byte array

问题描述

我使用这种方法（如下所示）读取WAV文件为一个字节数组。现在，我已经是存储在我的字节数组里面，我想改变的声音音量。

I'm reading a wav-file to a byte array using this method (shown below). Now that I have it stored inside my byte array, I want to change the sounds volume.

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：每请求对音频格式的一些信息：

Per request some info on the audio format:

PCM_SIGNED 44100.0赫兹，16位，单声道，2个字节/帧，小尾数

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

从物理级的我记得您可以通过正弦值0和1之间的数字乘以改变正弦波的幅度。

From physics-class I remembered that you can change the amplitude of a sine-wave by multiplying the sine-value with a number between 0 and 1.

编辑：更新code 16位样本：

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;
}

声音是严重扭曲的，如果我乘 audioSample 与卷。如果我不和比较两个数组Arrays.compare（数组，audioSample）我可以断定字节数组被转换为正确int和周围的其他方法

The sound is heavily distorted if I multiply audioSample with volume. If I don't and compare both arrays with Arrays.compare(array, audioSample) I can conclude that the byte-array is being converted correctly to int and the other way around.

任何人可以帮助我吗？我究竟得到什么错在这里？谢谢！ ：）

Can anybody help me out? What am I getting wrong here? Thank you! :)

推荐答案

您确定您正在阅读的8位单声道音频？否则，一个字节不等于一个样品，你可以不只是规模的每个字节。例如。如果它是16位的数据必须要分析每对字节作为一个16位的整数的，规模是，然后将它写回为两个字节。

Are you sure you're reading 8-bit mono audio? Otherwise one byte does not equal one sample, and you cannot just scale each byte. E.g. if it is 16-bit data you have to parse every pair of bytes as a 16-bit integer, scale that, and then write it back as two bytes.

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