Track LP reflection coefficients

Linear Prediction analysis of audio signals using the autocorrelation method and Durbin recursion, implemented in the libassp C library (Scheffers 2012) . Returns per-frame RMS amplitudes and reflection coefficients. Use trk_rfc when a lattice-filter or PARCOR representation of the vocal tract is needed.

Usage

trk_rfc(listOfFiles = NULL,
  beginTime = 0.0,
  centerTime = FALSE,
  endTime = 0.0,
  windowShift = 5.0,
  windowSize = 20.0,
  effectiveLength = TRUE,
  window = 'BLACKMAN',
  analysisOrder = NULL,
  preemphasis = -0.95,
  toFile = FALSE,
  explicitExt = NULL,
  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.
beginTime: Numeric. Start of analysis window in seconds. Default 0 (file start).
centerTime: Numeric or logical. Single-frame analysis time point in seconds; overrides beginTime, endTime, and windowShift. Default FALSE.
endTime: Numeric. End of analysis window in seconds. Default 0 (file end).
windowShift: Numeric. Frame shift in milliseconds; sets output frame rate (1000 / windowShift Hz). Default 5 ms.
windowSize: Numeric. Analysis window size in milliseconds. Default 20 ms.
effectiveLength: Logical. Make window size effective rather than exact. Default FALSE.
window: Character. Analysis window function type. Default "BLACKMAN". See AsspWindowTypes.
analysisOrder: Integer. LP order; NULL or 0 defaults to sample rate in kHz + 3. Default NULL.
preemphasis: Numeric. Pre-emphasis factor. Default -0.95.
toFile: Logical. If TRUE, write SSFF output files and return the count written (invisibly). If FALSE, return an AsspDataObj. Default FALSE.
explicitExt: Character. Output file extension override. Default NULL (uses "rfc").
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 FALSE.

Value

If toFile = FALSE: an AsspDataObj with tracks:

RMS[dB]: REAL32, dB, n_frames x 1. RMS amplitude of the input frame.
gain[dB]: REAL32, dB, n_frames x 1. RMS amplitude of the LP residual.
RFC: REAL32, dimensionless, n_frames x analysisOrder columns. Reflection (PARCOR) coefficients, one per LP order.

Frame rate: 1000 / windowShift Hz (default 200 Hz). If toFile = TRUE: integer count of files written, returned invisibly.

Details

analysisOrder = NULL selects an order equal to sample rate in kHz + 3. Pre-emphasis is applied before LP analysis and affects the residual gain.

References

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

Author

Raphael Winkelmann

Lasse Bombien

Fredrik Nylén

Examples

path2wav <- list.files(system.file("samples", "sustained", package = "superassp"),
                       pattern = glob2rx("a1.wav"), full.names = TRUE)
res <- trk_rfc(path2wav, toFile = FALSE)
#> Applying `rfcana()` to 1 recording
matplot(seq(0, n_records(res) - 1) / sample_rate(res) +
          attr(res, "startTime"),
        res$RFC, type = "l",
        xlab = "time (s)", ylab = "Reflection coefficient values")