如何在android中播放旋律？

Question

我如何在android 5中播放旋律，比如440‘s，480’s，500‘s，440’s？其他系统也有一些东西。比如"sound(440)“。或者我必须用AudioTrack合成它？

Answer 1

是的，正如@zed指出的那样，你必须使用AudioTrack来合成它。

这里有一些代码可以帮助你

 final static double scale = 1;
 final static int duration = 50; // Seconds
 final static int sampleRate = 22050; // Hz (maximum frequency is 7902.13Hz (B8))
 final static int numSamples = duration * sampleRate;
 final static double samples[] = new double[numSamples];
 final static short buffer[] = new short[numSamples];


double note = scale * frequency;
for (int i = 0; i < numSamples; ++i)
 {
      samples[i] = Math.sin(2 * Math.PI * i / (sampleRate / note)); // Sine wave
      buffer[i] = (short) (samples[i] * Short.MAX_VALUE);  // Higher amplitude increases volume
 }

audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,sampleRate,AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, buffer.length,AudioTrack.MODE_STATIC);
audioTrack.write(buffer, 0, buffer.length);