Vamp

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OpenScofo is also available as a Vamp plugin for offline audio feature extraction. It is designed to be used in host applications like Sonic Visualiser or Audacity.

Note on Score Following

Due to inherent limitations in the architecture of Vamp plugins, which are strictly designed for offline analysis and do not support dynamic string-based file parsing from the host GUI during processing, this plugin does NOT perform score following. Instead, it acts as a comprehensive audio descriptor extractor, exposing all of OpenScofo's internal feature extraction capabilities directly to your Vamp host.

Features

The plugin analyzes incoming audio blocks (default size: 2048 samples, step size: 512 samples) and outputs a wide array of both vector and scalar descriptors.

Vector Descriptors (Arrays)

These output multiple values per step (e.g., bins or bands):

MFCC (13 bins)
LogMelSpectrum / Melogram (40 bins)
Chroma (12 bins)

Scalar Descriptors (Single Values)

These output a single continuous value per step:

Amplitude & Energy: Max Amplitude, Loudness, RMS, dB, Amplitude Standard Deviation.
Spectral Features: Spectral Flux, Spectral Irregularity, Spectral Crest, Spectral Centroid, Spectral Spread (Hz), Spectral Spread Variance, Spectral Flatness, High Frequency Ratio.
Pitch & Tone: Pitch, Pitch Confidence, Harmonicity, Zero Crossing Rate.
Probabilities & Classifications: Onset Probability, Silence Probability, Extended Technique Probability.
Motion: Centroid Velocity.

Usage (e.g., in Sonic Visualiser)

Ensure the compiled Vamp plugin library (.so, .dylib, or .dll) is placed in your system's standard Vamp plugin directory.
Open your audio file in Sonic Visualiser.
Go to Transform > Analysis by Plugin Name > Open Score Follower.
Select the specific descriptor you wish to visualize (e.g., MFCC, Pitch, Spectral Centroid, etc).
The host will process the audio offline and draw the requested descriptor data over your waveform/spectrogram.