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Audio Analysis
On this page
  1. Commands
  2. Fields
  3. Output variables

Audio Analysis

Analyzes the level and frequency distribution of audio in real time using FFT (Fast Fourier Transform). Audio analyzers and their source (microphone or speaker) are registered in Settings > Audio Analyzer.

Audio Analyzer

Select the audio analyzer to use.

Commands

  • Start Analysis (default): Starts audio analysis.
  • Stop Analysis: Stops audio analysis.
  • Add Analysis: Adds an analysis to the analyzer. Several analyses can be added to one analyzer.
  • Clear All Analyses: Removes all analyses from the analyzer.
Caution An analysis is registered with Add Analysis and produces values only after Start Analysis has been run. If the start is omitted, the output variables stay empty.

Fields

All of the following fields are displayed only when Command is Add Analysis.

Data Type
  • Overall RMS (default): The RMS (root mean square) of all channels, representing the overall sound level.
  • Channel RMS: The RMS of the given channel, representing the sound level of that channel.
  • Frequency Amplitude: The intensity of a given frequency on the given channel.
  • Peak Intensity Frequency: The frequency with the highest intensity on the given channel, and that intensity.
  • Centroid Frequency: The center frequency where the energy is concentrated on the given channel. It represents the brightness of the sound: higher is bright and sharp, lower is dark and dull.
Channel

Enter the index of the channel to analyze, from 0 to 31. The channel layout depends on the audio source; typical numbers are as follows. Not displayed when Data Type is Overall RMS.

  • Mono: 0
  • Stereo: 0 left, 1 right
  • 5.1 channels: 0 front left, 1 front right, 2 center, 3 subwoofer, 4 rear left, 5 rear right
Frequency (Hz)

Enter the frequency to analyze, from 0 to 50000 Hz. The default is 1000; the audible range is roughly 20 to 20000 Hz. Displayed only when Data Type is Frequency Amplitude.

Output variables

All take a Number variable.

  • Intensity (dBFS): Stores the intensity. dBFS is relative to the full-scale level (0 dB) of digital audio, so values are negative and closer to 0 means louder. Displayed when Data Type is Overall RMS, Channel RMS, or Frequency Amplitude.
  • Peak Frequency (Hz), Peak Intensity (dBFS): Store the frequency with the highest intensity and that intensity. Displayed when Data Type is Peak Intensity Frequency.
  • Centroid Frequency (Hz): Stores the centroid frequency. Displayed when Data Type is Centroid Frequency.