!7

// Note: This is dependent on input buffer size which is not optimal.

// Tested with buffer size 232 ms (using CD quality)

cmodule VAD > DynPrintLogAndEnabled {

  switchable double windowSize = 1; // milliseconds

  switchable double threshold =

    // 10.0; // the magic value for 44 KHz stereo

    1; // for 8 KHz mono

  transient double confidence;

  transient short[] fromData; // only useful when sendOutClonedData = true

  start {

    printLogUpdateInterval = 100;

    // technically we are treating stereo input as mono samples

    // but it might not matter

    dm_addAudioListener(voidfunc(short[] data) enter {

      if (!enabled) ret;

      short[] buffer = cloneArray(data);

      dm_q(r {

        if (q.size() > 2) ret with print("overload");

        short[] buf = buffer;

        //printStruct(takeFirstOfShortArray(8, buf));

        float sampleRate = dm_audioInputSampleRate();

        if (sampleRate == 0) ret;

        float originalSampleRate = sampleRate;

        int channels = dm_audioInputChannels();

        if (channels > 1) buf = mixStereoShortArrayToMono(buf);

        buf = convertSampleRate_shortArray_simple(buf, sampleRate, 8000);

        sampleRate = 8000f;

        long time = sysNow();

        int windowLength = msToSamples_int(windowSize, sampleRate);

        //printWithMilliseconds("Window length (" + sampleRate + "): " + windowLength);

        new L<Double> l;

        L<IntRange> chunks = intRangeChunks(buf, windowLength);

        for (IntRange r : chunks)

          l.add(normalizedAutocorrelationOfAudioSamples(buf, r));

        // print one table for reference  

        print(asList(normalizedAutocorrelationTableForAudioSamples(buf, first(chunks))));

        double result = doubleAverage(l);

        confidence = result/threshold*50;

        fromData = data;

        int vol = shortAbsMax(buf);

        print("VAD " + (confidence >= 50 ? "XXX" : "   ") + " value: " + iround(confidence) + " % [" + elapsedMS(time) + " ms, "

          + nWindows(l(buf)/windowLength) + " of size " + windowLength + ", converted from \*originalSampleRate*/ Hz, " + nChannels(channels) + ", volume: " + iround(vol/32767.0*100) + "]");

      });

    });

  }

  // API

  Bool hasVoiceActivity(short[] fromData) {

    ret fromData != this.fromData ? null : confidence >= 50;

  }

}