wrassp (version 0.1.2)

dftSpectrum: dftSpectrum

Description

DFT spectrum function adapted from libassp

Usage

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

Arguments

listOfFiles

vector of file paths to be processed by function

optLogFilePath

path to option log file

beginTime

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

centerTime

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

endTime

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

resolution

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

fftLength

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

windowShift

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

window

= : set analysis window function to (default: BLACKMAN)

bandwidth

= : set the effective analysis bandwidth to Hz (default: 0, yielding the smallest possible value given the length of the FFT)

toFile

write results to file (default extension depends on )

explicitExt

set if you wish to overwride 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.

Value

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

Details

Short-term spectral analysis of the signal in using the Fast Fourier Transform. The default is to calculate an unsmoothed narrow-band spectrum with the size of the analysis window equal to the length of the FFT. The output from the FFT will be converted to a power spectrum in dB from 0 Hz up to and including the Nyquist rate. Analysis results will be written to a file with the base name of the input file and the spectrum type in lower case as extension (e.g. '.dft'). Default output is in SSFF format with the spectrum type in lower case as track name.

See Also

cssSpectrum, lpsSpectrum, cepstrum; 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]

# calculate dft spectrum
res <- dftSpectrum(path2wav, toFile=FALSE)

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