cutSampleEnds: Prepare Sample Object for appendSample

Description

Prepare a Sample object or a wav file for usage of appendSample to avoid cracks between two appended samples.

Usage

cutSampleEnds(s)

Arguments

a Sample object, or a string giving the name of a wav file.

Value

a Sample object.

Details

At the beginning of the sample, all values in the waveform until the first transition from negative to positive values are dropped, at the end everything after the last transition from negative to positive values is dropped. Currently, only channel 1 is used to determine which parts to drop. Hence in stereo samples there can still be some cracks in the right channel.

Examples

Run this code

s1 <- Sine(440,.01)
s2 <- Sine(550,.01)
s3 <- Sine(660,.01)
s4 <- Sine(880,.01)
l <- list(s1,s2,s3,s4)
#  first without cutSampleEnds:
s <- nullSample()
for (i in 1:99) {
  s <- appendSample(s,l[[i%%4+1]])
}
play(s) # ugly cracks
# now with cutSampleEnds:
s <- nullSample()
for (i in 1:99) {
  s <- appendSample(s,cutSampleEnds(l[[i%%4+1]]))
}
play(s) # no cracks,

# This is how it works:
# The waveform is not smooth between s1 and s2:
plot(appendSample(s1,s2))
# This is because s1 just ends somewhere at y=0.6:
plot(s1)
# Let's cut off the last positive part of it:
plot(cutSampleEnds(s1))
# A similar cuttoff would be made at the beginning
# of the sample (if it was necessary).
# Now the two samples fit perfectly (the cut is at x=400):
plot(appendSample(cutSampleEnds(s1),cutSampleEnds(s2)))