Module: FMOD::Core::WindowType

Defined in:

lib/fmod/core/window_type.rb

Overview

List of windowing methods for the Effects::FFT unit. Used in spectrum analysis to reduce leakage / transient signals interfering with the analysis.

This is a problem with analysis of continuous signals that only have a small portion of the signal sample (the FFT window size).

Windowing the signal with a curve or triangle tapers the sides of the FFT window to help alleviate this problem.

Cyclic signals such as a sine wave that repeat their cycle in a multiple of the window size do not need windowing. I.e. If the sine wave repeats every 1024, 512, 256 etc samples and the FMOD FFT window is 1024, then the signal would not need windowing.

Not windowing is the same as :rectangle, which is the default.

If the cycle of the signal (ie the sine wave) is not a multiple of the window size, it will cause frequency abnormalities, so a different windowing method is needed.

Constant Summary

RECT =

Rectangle.

w[n] = 1.0

0

TRIANGLE =

Triangle.

w[n] = TRI(2n/N)

1

HAMMING =

Hamming.

w[n] = 0.54 - (0.46 * COS(n/N) )

2

HANNING =

Hanning.

w[n] = 0.5 * (1.0 - COS(n/N) )

3

BLACKMAN =

Blackman.

w[n] = 0.42 - (0.5 * COS(n/N) ) + (0.08 * COS(2.0 * n/N) )

4

BLACKMAN_HARRIS =

Blackman-Harris.

w[n] = 0.35875 - (0.48829 * COS(1.0 * n/N)) + (0.14128 * COS(2.0 * n/N)) - (0.01168 * COS(3.0 * n/N))

5