/**
* Implements step 4 of the AUBIO_YIN paper.
*/
private int absoluteThreshold()
{
// Uses another loop construct
// than the AUBIO implementation
int tau;
// first two positions in yinBuffer are always 1
// So start at the third (index 2)
for (tau = 2; tau < yinBuffer.Length; tau++)
{
if (yinBuffer[tau] < threshold)
{
while (tau + 1 < yinBuffer.Length && yinBuffer[tau + 1] < yinBuffer[tau])
{
tau++;
}
// found tau, exit loop and return
// store the probability
// From the YIN paper: The threshold determines the list of
// candidates admitted to the set, and can be interpreted as the
// proportion of aperiodic power tolerated
// within a periodic signal.
//
// Since we want the periodicity and and not aperiodicity:
// periodicity = 1 - aperiodicity
result.setProbability(1 - yinBuffer[tau]);
break;
}
}
// if no pitch found, tau => -1
if (tau == yinBuffer.Length || yinBuffer[tau] >= threshold)
{
tau = -1;
result.setProbability(0);
result.setPitched(false);
}
else
{
result.setPitched(true);
}
return(tau);
}
