如何在Android中轻松地生成合成和弦的声音？

Question

如何在Android中轻松地生成合成和弦的声音？我想要能够动态生成一个游戏中的音乐使用8位。尝试了与AudioTrack，但没有得到良好的效果良好的声音。

有什么例子吗？

我尝试了以下代码，但没有成功：

public class BitLoose {
    private final int duration = 1; // seconds
    private final int sampleRate = 4200;
    private final int numSamples = duration * sampleRate;
    private final double sample[] = new double[numSamples];

    final AudioTrack audioTrack;

    public BitLoose() {
        audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                sampleRate, AudioFormat.CHANNEL_CONFIGURATION_MONO,
                AudioFormat.ENCODING_PCM_8BIT, numSamples,
                AudioTrack.MODE_STREAM);
        audioTrack.play();
    }

    public void addTone(final int freqOfTone) {
        // fill out the array
        for (int i = 0; i < numSamples; ++i) {
            sample[i] = Math.sin(2 * Math.PI * i / (sampleRate / freqOfTone));
        }

        // convert to 16 bit pcm sound array
        // assumes the sample buffer is normalised.
        final byte generatedSnd[] = new byte[numSamples];

        int idx = 0;
        for (final double dVal : sample) {
            // scale to maximum amplitude
            final short val = (short) ((((dVal * 255))) % 255);
            // in 16 bit wav PCM, first byte is the low order byte
            generatedSnd[idx++] = (byte) (val);
        }
        audioTrack.write(generatedSnd, 0, sampleRate);
    }

    public void stop() {
        audioTrack.stop();
    }

Answer 1

我认为不好的声音是由音频格式造成的: AudioFormat.ENCODING_PCM_8BIT使用无符号示例，所以必须将1到-1之间的正弦值转换为0-255字节值，尝试如下：

for (final double dVal : sample) {
    final short val = (short) ((dVal + 1) / 2 * 255) ;
    generatedSnd[idx++] = (byte) val;
}

还请尝试将采样率更改为11025，因为在某些设备上可能不支持4200：

private final int sampleRate = 11025;