wrassp (version 1.0.5)

cepstrum: cepstrum

Description

calculate cepstral coefficients using libassp

Usage

cepstrum(
  listOfFiles = NULL,
  optLogFilePath = NULL,
  beginTime = 0,
  centerTime = FALSE,
  endTime = 0,
  resolution = 40,
  fftLength = 0,
  windowShift = 5,
  window = "BLACKMAN",
  toFile = TRUE,
  explicitExt = NULL,
  outputDirectory = NULL,
  forceToLog = useWrasspLogger,
  verbose = TRUE
)

Value

nrOfProcessedFiles or if only one file to process return AsspDataObj of that file

Arguments

listOfFiles

vector of file paths to be processed by function

optLogFilePath

path to option log file

beginTime

= <time>: set begin of analysis interval to <time> seconds (default: begin of data)

centerTime

= <time>: set single-frame analysis with the analysis window centred at <time> seconds; overrules beginTime, endTime and windowShift options

endTime

= <time>: set end of analysis interval to <time> seconds (default: end of data)

resolution

= <freq>: set FFT length to the smallest value which results in a frequency resolution of <freq> Hz or better (default: 40.0)

fftLength

= <num>: set FFT length to <num> points (overrules default and 'resolution' option)

windowShift

= <dur>: set analysis window shift to <dur> ms (default: 5.0)

window

= <type>: set analysis window function to <type> (default: BLACKMAN)

toFile

write results to file (default extension depends on )

explicitExt

set if you wish to override the default extension

outputDirectory

directory in which output files are stored. Defaults to NULL, i.e. the directory of the input files

forceToLog

is set by the global package variable useWrasspLogger. This is set to FALSE by default and should be set to TRUE is logging is desired.

verbose

display infos & show progress bar

Author

Raphael Winkelmann

Lasse Bombien

Details

Short-term cepstral analysis of the signal in <listOfFiles> using the Fast Fourier Transform. The number of coefficients per output record will also equal the FFT length / 2 + 1 (i.e. be non-mirrored). Analysis results will be written to a file with the base name of the input file and as extension '.cep'. Default output is in SSFF format with 'cep' as track name.

See Also

dftSpectrum, cssSpectrum, lpsSpectrum; all derived from libassp's spectrum function

Examples

# get path to audio file
path2wav <- list.files(system.file("extdata", package = "wrassp"), 
                       pattern = glob2rx("*.wav"), 
                       full.names = TRUE)[1]

# calulate cepstrum
res <- cepstrum(path2wav, toFile=FALSE)

# plot cepstral values at midpoint of signal
plot(res$cep[dim(res$cep)[1]/2,], 
     type='l', 
     xlab='cepstral value index', 
     ylab='cepstral value')