R: 2D-cepstrogram of a time wave

cepstro {seewave}

R Documentation

2D-cepstrogram of a time wave

Description

This function returns a two-dimension cepstrographic representation of a time wave. The function corresponds to a short-term cepstral transform. An amplitude contour plot can be overlaid.

Usage

cepstro(wave, f, channel = 1, wl = 512, ovlp = 0, plot = TRUE, grid = TRUE,
scale = TRUE, cont = FALSE, collevels = seq(0, 1, 0.01),
palette = reverse.heat.colors, contlevels = seq(0, 1, 0.01),
colcont = "black", colbg="white", colgrid = "black",
colaxis = "black", collab = "black",
xlab = "Time (s)", ylab = "Quefrency (ms)",
scalelab = "Amplitude", main = NULL, scalefontlab = 1, scalecexlab = 0.75,
axisX = TRUE, axisY = TRUE, tlim = NULL, qlim = NULL, ...)

Arguments

`wave`	an R object.
`f`	sampling frequency of `wave` (in Hz). Does not need to be specified if embedded in `wave`.
`channel`	channel of the R object, by default left channel (1).
`wl`	if `at` is not null, length of the window for the analysis (even number of points, by defaults = 512).
`ovlp`	overlap between two successive windows (in %).
`plot`	logical, if `TRUE` plots the cepstrogram (by default `TRUE`).
`grid`	logical, if `TRUE` plots a y-axis grid (by default `TRUE`).
`scale`	logical, if `TRUE` plots a dB colour scale on the right side of the cesptrogram (by default `TRUE`).
`cont`	logical, if `TRUE` overplots contour lines on the cepstrogram (by default `FALSE`).
`collevels`	a set of levels which are used to partition the amplitude range of the cepstrogram (in dB).
`palette`	a color palette function to be used to assign colors in the plot.
`contlevels`	a set of levels which are used to partition the amplitude range for contour overplot (in dB).
`colcont`	colour for `cont` plotting.
`colbg`	background colour.
`colgrid`	colour for `grid` plotting.
`colaxis`	color of the axes.
`collab`	color of the labels.
`xlab`	label of the time axis.
`ylab`	label of the quefrency axis.
`main`	label of the main title.
`scalelab`	amplitude scale label.
`scalefontlab`	font of the amplitude scale label.
`scalecexlab`	cex of the amplitude scale label.
`axisX`	if `TRUE` plots time X-axis (by default `TRUE`).
`axisY`	if `TRUE` plots frequency Y-axis (by default `TRUE`).
`tlim`	modifications of the time X-axis limits.
`qlim`	modifications of the quefrency Y-axis limits (in ms).
`...`	other `contour` graphical parameters.

Details

It is unfortunately not possible to turn the y-axis to a frequency scale.
See spectro for the use of the graphical arguments.

Value

This function returns a list of three items:

`time`	a numeric vector corresponding to the time axis.
`freq`	a numeric vector corresponding to the quefrency axis.
`amp`	a numeric matrix corresponding to the the successive cepstral profiles computed along time.

Note

This function is based on ceps.

Author(s)

Jerome Sueur sueur@mnhn.fr.

References

Oppenheim, A.V. and Schafer, R.W. 2004. From frequency to quefrency: a history of the cepstrum. Signal Processing Magazine IEEE, 21: 95-106.

Examples

data(sheep)
sheepc <- cutw(sheep, f=8000, from = 0.19, to = 2.3)
cepstro(sheepc,f=8000)

[Package seewave version 2.1.6 Index]