drawenv: Draw the amplitude envelope of a time wave

Description

This function lets the user modifying the amplitude envelope of a time wave by drawing it with the graphics device

Usage

drawenv(wave, f, n = 20, plot = FALSE, listen = FALSE, Sample = FALSE)

Arguments

wave

a vector, a matrix (first column), an object of class ts, Sample (left channel), or Wave (left channel).

sampling frequency of wave (in Hz). Does not need to be specified if wave is an object of class ts, Sample, or Wave<

the maximum number of points to draw the new envelope. Valid values start at 1.

plot

if TRUE returns the oscillogram of the new time wave (by default FALSE).

listen

if TRUE the new sound is played back.

Sample

if TRUE and plot is FALSE returns an object of class Sample.

Value

If plot is FALSE, a new wave is returned as a one-column matrix or as a Sample object if Sample is TRUE.

Details

The function first plots an oscillogram view of wave. The user has then to choose points on the positive side of the y-axis (amplitude). The junction of these points will draw a new amplitude envelope. The order of points along the x-axis (time) is not important but points cannot be cancelled. When this process is finished the new time wave is returned in the console or as an oscillogram in a second graphics device if plot is TRUE. The function uses locator.

Examples

Run this code

a<-synth(d=1,f=22050,cf=1000)
# drawenv(a,f=22050,plot=TRUE)
# choose points on the oscillogram view to draw a new enveloppe
# stop (ESC on Windows; right mouse button on Linux)
# check the result on the second graphics device opened thanks to plot=TRUE

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