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Audio Analysis
Emmanouil Benetos
Introduction
Goal: extracting low- and mid-level descriptors
from individual audio recordings
To be used for high-level musicological analysis
Using (mostly) existing audio analysis technologies
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Low-level audio descriptors
(e.g. raw audio, spectrograms, onsets)
Mid-level audio descriptors
(e.g. pitches, chords, beats)
High-level audio descriptors
(e.g. temperament, instrumentation, chord/note patterns)
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The DML Project: Audio Analysis
Audio Descriptors List
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Spectrogram
MFCCs
Chroma
Onsets
Speech/Music Segmentation
Chords
Beats/Tempo
Key
Melody
Note Transcription
The DML Project: Audio Analysis
Raw Audio
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Sample from CHARM: JS Bach, Chorale Prelude - Beloved Jesus, Cohen, Harriet
(piano), Columbia, 1935
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The DML Project: Audio Analysis
Spectrogram
2 versions:
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STFT magnitude spectrogram
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Constant-Q Transform magnitude spectrogram
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The DML Project: Audio Analysis
MFCCs
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Stand for: Mel-Frequency Cepstral Coefficients
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Extracted using QM Vamp Plugin Set
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The DML Project: Audio Analysis
Chroma
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Spectrum projected onto 12 bins (representing semitones of an octave)
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Extracted using: QM Chromagram and NNLS Chroma Vamp plugins
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The DML Project: Audio Analysis
Onsets
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Onset: the beginning of a musical note or another sound
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Extracted using QM Onset Vamp plugin
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The DML Project: Audio Analysis
Speech/Music Segmentation
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Useful for ethnographic recordings/radio broadcasts
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Extracted using BBC Speech/Music Segmentation Vamp Plugin
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The DML Project: Audio Analysis
Chords
Extracted using Chordino Vamp Plugin
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The DML Project: Audio Analysis
Beats
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Beat locations labelled with metrical position
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Extracted using Beatroot, Marsyas, Tempotracker Vamp Plugins
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The DML Project: Audio Analysis
Tempo
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Estimated based on onset/beat information
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Extracted using Tempotracker and Tempogram Vamp plugins
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The DML Project: Audio Analysis
Key
Extracted using QM Key Vamp plugin (supports major/minor keys)
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The DML Project: Audio Analysis
Melody
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Or more precisely: “Sequence of fundamental frequency (F0) values
corresponding to the perceived pitch of the main melody.”
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Extracted using MELODIA Vamp plugin
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The DML Project: Audio Analysis
Note Transcription – Semitone Resolution
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Multiple-pitch detection (onset/offset/pitch/velocity)
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Extracted using Silvet Vamp plugin
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Synthesized transcription example:
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The DML Project: Audio Analysis
Note Transcription – High Pitch Resolution
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Multiple-pitch detection on a 20-cent resolution – useful for
tuning/temperament analysis and analysis of non-Western music
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Extracted using Silvet Vamp plugin
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The DML Project: Audio Analysis
Thank you!
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The DML Project: Audio Analysis