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Apply Compiled Window Function (Advanced Performance API)

Source: R/performance-helpers.R
apply_window_xptr.Rd

Apply a user-defined C++ window function to a Sound object, compiled via RcppXPtrUtils, instead of calling an R callback per sample. Requires the RcppXPtrUtils package.

Usage

apply_window_xptr(sound, window_func)

Arguments

sound

Sound object or external pointer

window_func

External pointer from RcppXPtrUtils::cppXPtr()

Value

Sound object with window function applied

Details

**ADVANCED API** - Requires RcppXPtrUtils package.

The window function receives normalized time (0 to 1) and returns a multiplier. Common window functions:

  • Hamming: `0.54 - 0.46 * cos(2 * M_PI * t)`

  • Hanning: `0.5 * (1 - cos(2 * M_PI * t))`

  • Gaussian: `exp(-18 * (t - 0.5)^2)`

  • Triangular: `1 - fabs(2*t - 1)`

Examples

# \donttest{
# Compiling a C++ window function takes a few seconds
if (requireNamespace("RcppXPtrUtils", quietly = TRUE)) {
  gauss_window <- RcppXPtrUtils::cppXPtr(
    "double gauss(double t) {
      double x = t - 0.5;
      return exp(-18.0 * x * x);
    }",
    depends = character()
  )

  # Verify signature (optional but recommended)
  RcppXPtrUtils::checkXPtr(gauss_window, "double", "double")

sound <- Sound$create_tone(frequency = 220, duration = 0.3, sampling_rate =
 16000)
  windowed <- apply_window_xptr(sound, gauss_window)
}
# }