Method BPMDetect

lib-src/soundtouch/source/SoundTouch/BPMDetect.cpp:110–151

BPMDetect::BPMDetect(int numChannels, int aSampleRate)
{
    this->sampleRate = aSampleRate;
    this->channels = numChannels;

    decimateSum = 0;
    decimateCount = 0;

    envelopeAccu = 0;

    // Initialize RMS volume accumulator to RMS level of 1500 (out of 32768) that's
    // safe initial RMS signal level value for song data. This value is then adapted
    // to the actual level during processing.
#ifdef SOUNDTOUCH_INTEGER_SAMPLES
    // integer samples
    RMSVolumeAccu = (1500 * 1500) / avgnorm;
#else
    // float samples, scaled to range [-1..+1[
    RMSVolumeAccu = (0.045f * 0.045f) / avgnorm;
#endif

    // choose decimation factor so that result is approx. 1000 Hz
    decimateBy = sampleRate / 1000;
    assert(decimateBy > 0);
    assert(INPUT_BLOCK_SAMPLES < decimateBy * DECIMATED_BLOCK_SAMPLES);

    // Calculate window length & starting item according to desired min & max bpms
    windowLen = (60 * sampleRate) / (decimateBy * MIN_BPM);
    windowStart = (60 * sampleRate) / (decimateBy * MAX_BPM);

    assert(windowLen > windowStart);

    // allocate new working objects
    xcorr = new float[windowLen];
    memset(xcorr, 0, windowLen * sizeof(float));

    // allocate processing buffer
    buffer = new FIFOSampleBuffer();
    // we do processing in mono mode
    buffer->setChannels(1);
    buffer->clear();
}