Question

如何在Android中轻松生成合成和弦声音？我想能够使用8bit动态生成游戏音乐。试过 AudioTrack ，但还没有得到好听的好结果。

那里有任何例子吗？

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

我认为声音质量不好是因为音频格式：AudioFormat.ENCODING_PCM_8BIT使用无符号样本，所以1到-1之间的正弦必须转换为0-255字节值，试试这个：

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

还要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;

Answer 2

除了答案1，你应该使用：
sample [i] = Math.sin（2 * Math.PI * i /（（double） sampleRate / freqOfTone））;
而不是 sample [i] = Math.sin（2 * Math.PI * i /（sampleRate / freqOfTone））;

如何在Android中轻松生成Synth和弦声音？

2 个答案: