seewave (version 1.7.6)

cepstro: 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, wl = 512, ovlp = 0, plot = TRUE, grid = TRUE,
scale = TRUE, cont = FALSE, collevels = seq(0, 1, 0.01),
palette = rev.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, ...)

Arguments

wave

an R object.

f

sampling frequency of wave (in Hz). Does not need to be specified if embedded in wave.

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, see Details.

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).

...

other contour graphical parameters.

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.

Details

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

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.

See Also

ceps, fund, autoc

Examples

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