A plugin collection for various Vamp Analyzers. The plugins included are all open source software developed and published by various different authors and institutions:
BBC
Carl Bussey
Chris Cannam
Jamie Bullock
Download page:
This analyzer was developed as an aid for audiobook producers. It displays a number of useful statistics about the selected audio, and compares them to the specifications published by (an Amazon.com subsidiary).
A Goniometer, also known as XY-Oscilloscope or Phase Scope.
Note: Requires registration. This Analyzer can be found in the Effects category.
Either places a single label at the first instance of a peak volume, or multiple labels at all the instances of that peak.
This plugin attempts to detect and display the musical pitch and frequency of the selected note. In most cases the default settings will work best. The other options are provided to handle special cases such as analyzing synthetic signals that are outside of the usual musical range.
Additional Vamp Plugins can be found on
Marsyas Plugins
Matthias Mauch
Paul Brossier
Queen Mary, University of London
Simon Dixon and Chris Cannam
University of Alicante
RMS level The RMS level of the selected audio.
Noise floor The RMS level of the quietest 500 milliseconds in the selection
Warnings: (These are only displayed when applicable.)
Warning: ACX require 44100 Hz sample rate.
Warning: ACX require running time no longer than 120 minutes
Noise floor: -inf dB Warning (too low - Dead silence sounds unnatural.) ACX require constant, low level "room tone" rather than an unnaturally silent background noise level.
Limitations
This tool is intended only as an aid in achieving ACX acceptance. Even straight passes from this tool is NO guarantee of ACX acceptance.
The Noise Floor measurement is taken from the quietest half second of audio found in the selection. If one part of the selection is quieter than the rest, you will get a false value.
Minimum selection length is 1/2 second.
Maximum selection length is about 2.14 billion samples (13.5 hours at a sample rate of 44100 Hz)
Also beware that some noise sources are worse than others, and noise such as the 1000 Hz whine that often happens in USB audio interfaces may result in an ACX rejection even though it is below the -60 dBFS noise floor requirement.
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Limitations
This effect can be very slow on long selections.
If the audio is clipped and "Place labels at: all equally loud peaks" is selected, there may be an extremely large number of labels created. The "Minimum Distance" setting is useful to reduce the number of labels.
Peaks that appear to be at the maximum amplitude will not be labeled unless they are exactly at the maximum amplitude.
Analyse first (seconds): [0.1 to 1. Default 0.2] At the default setting the first 0.2 seconds of the selection will be analyzed.
Limitations
This plugin is intended to detect single notes - you may get strange results if you try to analyze chords.
Extremely high frequencies may not be detected very accurately, especially if the sample rate is not very high. The plugin will often detect very high frequencies better if the sample rate is 96000 Hz rather than 44100 Hz.
The plugin should usually be able to detect pitches of single notes to within a few percent of the actual frequency. Don't expect the frequency in Hz to be exact..
Advanced usage tips
For detecting very low frequencies (less than a few hundred Hz) the plugin should be set to the low frequency range (20 to 1000 Hz).
For detecting very high frequencies (several kHz) the plugin should be set to the high frequency range (1 kHz to 10 kHz).
For measuring synthesized tones and other electronic signals, the most accurate measure of frequency in Audacity is to use "Plot Spectrum" and set the "Size" setting to a high value.
