How to easily Generate Synth Chords Sounds in Android? I wanna be able to generate dynamically an in game Music using 8bit. Tried with AudioTrack, but did not get good results of nice sounds yet.
Any examples out there?
I have tried the following code without success:
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) (va开发者_运维问答l);
}
audioTrack.write(generatedSnd, 0, sampleRate);
}
public void stop() {
audioTrack.stop();
}
I think that bad sound is due to audio format: AudioFormat.ENCODING_PCM_8BIT uses unsigned samples, so a sine between 1 and -1 must be converted to 0-255 byte values, try this:
for (final double dVal : sample) {
final short val = (short) ((dVal + 1) / 2 * 255) ;
generatedSnd[idx++] = (byte) val;
}
Try also to change sample rate to 11025, because 4200 may be unsupported on some devices:
private final int sampleRate = 11025;
Apart from answer 1 you should use:
sample[i] = Math.sin(2 * Math.PI * i / ((double) sampleRate / freqOfTone));
instead of
sample[i] = Math.sin(2 * Math.PI * i / (sampleRate / freqOfTone));
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