findZeroCrossing {soundgen} | R Documentation |
Find zero crossing
Description
Internal soundgen function.
Usage
findZeroCrossing(ampl, location)
Arguments
ampl |
a vector of amplitudes oscillating around zero, such as a sound waveform |
location |
the index indicating the desired location of a zero crossing |
Details
findZeroCrossing
looks for the last negative point before a zero
crossing as close as possible to the specified location. Since this is
primarily intended for joining waveforms without a click, this function only
looks at upward segments of a waveform (see example).
Value
Returns the index of the last negative value before zero crossing closest to specified location.
Examples
ampl = sin(1:100/2)
plot(ampl, type = 'b')
lines(1:100, rep(0,100), lty = 2)
zc = vector()
for (i in seq_along(ampl)){
zc[i] = soundgen:::findZeroCrossing (ampl, i)
# find zc closest to each of 100 points
}
for (z in unique(zc)){
points(z, ampl[z], col = 'red', pch = 17)
# only on upward segments
}
zc # see which zc is closest to each point
[Package soundgen version 2.7.2 Index]