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Differentiate an audio waveform

trk_afdiff.Rd

Applies a first-order finite-difference filter to audio signals using the libassp C library (Scheffers 2012) . Forward, backward, and central difference modes are supported. Useful for pre-emphasising high frequencies or computing the derivative of a waveform before further analysis.

Usage

trk_afdiff(listOfFiles, computeBackwardDifference = FALSE, computeCentralDifference = FALSE, channel = 1L, beginTime = 0, endTime = 0, toFile = TRUE, explicitExt = "dif", outputDirectory = NULL, assertLossless = NULL, logToFile = FALSE, keepConverted = FALSE, convertOverwrites = FALSE, verbose = TRUE)

Arguments

listOfFiles

Character vector of audio file paths. Any format supported by av is accepted; non-native inputs are transcoded automatically.

computeBackwardDifference

Logical. Use backward difference instead of forward. Default FALSE.

computeCentralDifference

Logical. Use central difference instead of forward. Default FALSE.

channel

Integer. Audio channel to process (1-based). Default 1L.

beginTime

Numeric. Start of analysis window in seconds. Default 0 (file start).

endTime

Numeric. End of analysis window in seconds. Default 0 (file end).

toFile

Logical. If TRUE, write SSFF output files and return the count written (invisibly). If FALSE, return an AsspDataObj. Default TRUE.

explicitExt

Character. Output file extension. Default "dif".

outputDirectory

Character. Directory for output files. NULL (default) writes alongside the input file.

assertLossless

Character vector of additional file extensions to treat as losslessly encoded.

logToFile

Logical. Write processing log to a file in outputDirectory rather than the console. Default FALSE.

keepConverted

Logical. Retain intermediate transcoded files. Default FALSE.

convertOverwrites

Logical. Allow transcoding to overwrite existing files. Default FALSE.

verbose

Logical. Print per-file progress. Default TRUE.

Value

If toFile = FALSE: an AsspDataObj with track name preserved from libassp output (typically the same label as the input audio channel), containing INT16 or REAL32 differentiated sample values. If toFile = TRUE: integer count of files written, returned invisibly.

Details

At most one of computeBackwardDifference or computeCentralDifference should be TRUE. If both are FALSE (default), forward difference is used.

References

Scheffers M (2012). “Advanced Speech Signal Processor.” https://sourceforge.net/projects/libassp/files/libassp/.

Author

Fredrik Nylén

Examples

path2wav <- list.files(system.file("samples", "sustained", package = "superassp"),
                       pattern = glob2rx("a1.wav"), full.names = TRUE)
res <- trk_afdiff(path2wav, toFile = FALSE)
#> Applying `method(trk_afdiff, class_character)()` to 1 recording