Thanks guys.
Last question: I have to know Objective C and Java to cover both iOs and Android?
I found online code (this is C# I think) that is used to test Microphone inputs.
Can I use this for Android also, or I have to separately write it in Java?
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public class MicHandle : MonoBehaviour {
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private const int FREQUENCY = 48000; // Wavelength, I think.
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private const int SAMPLECOUNT = 1024; // Sample Count.
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private const float REFVALUE = 0.1f; // RMS value for 0 dB.
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private const float THRESHOLD = 0.02f; // Minimum amplitude to extract pitch (recieve anything)
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private const float ALPHA = 0.05f; // The alpha for the low pass filter (I don’t really understand this).
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public GameObject resultDisplay; // GUIText for displaying results
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public GameObject blowDisplay; // GUIText for displaying blow or not blow.
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public int recordedLength = 50; // How many previous frames of sound are analyzed.
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public int requiedBlowTime = 4; // How long a blow must last to be classified as a blow (and not a sigh for instance).
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public int clamp = 160; // Used to clamp dB (I don’t really understand this either).
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private float rmsValue; // Volume in RMS
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private float dbValue; // Volume in DB
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private float pitchValue; // Pitch - Hz (is this frequency?)
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private int blowingTime; // How long each blow has lasted
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private float lowPassResults; // Low Pass Filter result
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private float peakPowerForChannel; //
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private float[] samples; // Samples
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private float[] spectrum; // Spectrum
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private List<float> dbValues; // Used to average recent volume.
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private List<float> pitchValues; // Used to average recent pitch.
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public void Start () {
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samples = new float[SAMPLECOUNT];
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spectrum = new float[SAMPLECOUNT];
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dbValues = new List<float>();
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pitchValues = new List<float>();
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StartMicListener();
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}
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public void Update () {
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// If the audio has stopped playing, this will restart the mic play the clip.
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if (! audio.isPlaying) {
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StartMicListener();
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}
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// Gets volume and pitch values
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AnalyzeSound();
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// Runs a series of algorithms to decide whether a blow is occuring.
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DeriveBlow();
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// Update the meter display.
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if (resultDisplay){
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resultDisplay.guiText.text = “RMS: " + rmsValue.ToString(“F2”) + " (” + dbValue.ToString(“F1”) + " dB)\n" + “Pitch: " + pitchValue.ToString(“F0”) + " Hz”;
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}
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}
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/// Starts the Mic, and plays the audio back in (near) real-time.
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private void StartMicListener() {
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audio.clip = Microphone.Start(“Built-in Microphone”, true, 999, FREQUENCY);
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// HACK - Forces the function to wait until the microphone has started, before moving onto the play function.
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while (!(Microphone.GetPosition(“Built-in Microphone”) > 0)) {
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} audio.Play();
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}
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/// Credits to aldonaletto for the function, http://goo.gl/VGwKt
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/// Analyzes the sound, to get volume and pitch values.
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private void AnalyzeSound() {
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// Get all of our samples from the mic.
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audio.GetOutputData(samples, 0);
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// Sums squared samples
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float sum = 0;
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for (int i = 0; i < SAMPLECOUNT; i++){
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sum += Mathf.Pow(samples[i], 2);
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}
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// RMS is the square root of the average value of the samples.
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rmsValue = Mathf.Sqrt(sum / SAMPLECOUNT);
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dbValue = 20 * Mathf.Log10(rmsValue / REFVALUE);
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// Clamp it to {clamp} min
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if (dbValue < -clamp) {
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dbValue = -clamp;
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}
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// Gets the sound spectrum.
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audio.GetSpectrumData(spectrum, 0, FFTWindow.BlackmanHarris);
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float maxV = 0;
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int maxN = 0;
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// Find the highest sample.
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for (int i = 0; i < SAMPLECOUNT; i++){
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if (spectrum[i] > maxV spectrum[i] > THRESHOLD){
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maxV = spectrum[i];
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maxN = i; // maxN is the index of max
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}
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}
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// Pass the index to a float variable
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float freqN = maxN;
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// Interpolate index using neighbours
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if (maxN > 0 maxN < SAMPLECOUNT - 1) {
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float dL = spectrum[maxN-1] / spectrum[maxN];
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float dR = spectrum[maxN+1] / spectrum[maxN];
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freqN += 0.5f * (dR * dR - dL * dL);
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}
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// Convert index to frequency
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pitchValue = freqN * 24000 / SAMPLECOUNT;
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}
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private void DeriveBlow() {
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UpdateRecords(dbValue, dbValues);
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UpdateRecords(pitchValue, pitchValues);
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// Find the average pitch in our records (used to decipher against whistles, clicks, etc).
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float sumPitch = 0;
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foreach (float num in pitchValues) {
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sumPitch += num;
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}
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sumPitch /= pitchValues.Count;
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// Run our low pass filter.
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lowPassResults = LowPassFilter(dbValue);
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// Decides whether this instance of the result could be a blow or not.
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if (lowPassResults > -30 sumPitch == 0) {
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blowingTime += 1;
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} else {
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blowingTime = 0;
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}
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// Once enough successful blows have occured over the previous frames (requiredBlowTime), the blow is triggered.
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// This example says “blowing”, or “not blowing”, and also blows up a sphere.
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if (blowingTime > requiedBlowTime) {
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blowDisplay.guiText.text = “Blowing”;
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GameObject.FindGameObjectWithTag(“Meter”).transform.localScale *= 1.012f;
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} else {
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blowDisplay.guiText.text = “Not blowing”;
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GameObject.FindGameObjectWithTag(“Meter”).transform.localScale *= 0.999f;
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}
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}
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// Updates a record, by removing the oldest entry and adding the newest value (val).
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private void UpdateRecords(float val, List<float> record) {
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if (record.Count > recordedLength) {
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record.RemoveAt(0);
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}
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record.Add(val);
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}
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/// Gives a result (I don’t really understand this yet) based on the peak volume of the record
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/// and the previous low pass results.
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private float LowPassFilter(float peakVolume) {
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return ALPHA * peakVolume + (1.0f - ALPHA) * lowPassResults;
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}
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}
