getEnv: Get amplitude envelope

In soundgen: Sound Synthesis and Acoustic Analysis

Get amplitude envelope

Description

Calculates a smoothed envelope of a waveform based on peaks, running average, root mean square (intensity), or envelope of the analytic signal with Hilbert transform. Algorithm: calculates one envelope value per frame of length wl, then upsamples to the original sampling rate with spline.

Usage

getEnv(
  x,
  method = c("rms", "hil", "peak", "mean"),
  wl = 200,
  overlap = 0,
  step = NULL,
  upsample = TRUE
)

Arguments

x	numeric vector at least wl long
method	"peak" for peak amplitude per window, "rms" for root mean square amplitude, "mean" for mean (for DC offset removal), "hil" for Hilbert envelope
wl	the length of smoothing window (samples)
overlap	overlap between successive windows, 0 to 100%
step	step between successive windows (samples); overrides overlap
upsample	if TRUE, upsamples the envelope to the length of the original sound; if FALSE, returns one sample per window

Value

The envelope as a numeric vector on the original scale. If upsample = TRUE, it has the same length as the input, regardless of the amount of smoothing.

Examples

a = rnorm(500) * seq(1, 0, length.out = 500)
wl = 50
scale = max(abs(a))
plot(a, type = 'l', ylim = c(-scale, scale))
lines(getEnv(a, 'rms', wl), col = 'red')
lines(getEnv(a, 'peak', wl), col = 'green')
lines(getEnv(a, 'hil', wl), col = 'blue')
lines(getEnv(a, 'mean', wl), lty = 3, lwd = 3)

# No upsampling (short output)
getEnv(1:16, 'mean', wl = 5, upsample = FALSE)
env_short = getEnv(a, 'rms', wl = wl, overlap = 50, upsample = FALSE)
plot(a, type = 'l')
lines(seq(1, length(a), length.out = length(env_short)), env_short, col = 'red')

soundgen documentation built on Sept. 20, 2026, 5:07 p.m.