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CheapTrick Spectral Envelope Estimation (WORLD vocoder, C++ implementation)

trk_cheap_trick.Rd

Estimate the spectral envelope using the CheapTrick algorithm from the WORLD vocoder (Morise 2015). CheapTrick uses a Hanning-windowed, F0-adaptive spectral analysis to produce a smooth, high-quality power spectral envelope per frame.

Internally: F0 is extracted via Harvest (WORLD), then fed to CheapTrick. The output is a multi-column SSFF track (sp) with fft_size/2 + 1 spectral coefficients per frame, where fft_size is determined by fs and f0_floor following the WORLD formula.

All input media formats supported by av are accepted.

Usage

trk_cheap_trick(listOfFiles, beginTime = 0, endTime = 0, windowShift = 5, minF = 60, maxF = 400, voicing_threshold = 0.1, q1 = -0.15, f0_floor = 71, toFile = TRUE, explicitExt = "sp", outputDirectory = NULL, verbose = TRUE)

Arguments

listOfFiles

Character vector of audio file paths.

beginTime

Numeric. Start of analysis window in seconds. Default 0.

endTime

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

windowShift

Numeric. Frame shift in milliseconds. Default 5.0 ms.

minF

Numeric. Minimum F0 in Hz for the Harvest pitch extractor. Default 60.0 Hz.

maxF

Numeric. Maximum F0 in Hz for the Harvest pitch extractor. Default 400.0 Hz.

voicing_threshold

Numeric. Voicing threshold for Harvest (default 0.1).

q1

Numeric. CheapTrick spectral regularization parameter (default -0.15).

f0_floor

Numeric. Lower F0 bound used to determine FFT size (default 71.0). For 16 kHz audio, 71 Hz gives fft_size = 2048 (sp_length = 1025).

toFile

Logical. If TRUE, write SSFF output and return count invisibly. If FALSE, return AsspDataObj. Default TRUE.

explicitExt

Character. Output file extension. Default "sp".

outputDirectory

Character. Output directory. NULL (default) writes alongside the input file.

verbose

Logical. Print per-file progress. Default TRUE.

Value

If toFile = FALSE: an AsspDataObj with track:

sp

REAL32, power spectral envelope, n_frames x (fft_size/2+1).

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

Examples

if (FALSE) { # \dontrun{
# Estimate spectral envelope
trk_cheap_trick("recording.wav")

# Return data without writing file
sp <- trk_cheap_trick("recording.wav", toFile = FALSE)
dim(sp$sp)  # n_frames x 1025 for 16 kHz audio

# Process multiple files
trk_cheap_trick(c("file1.wav", "file2.wav"))
} # }