4/14/2023 0 Comments Chordino chord dictionary![]() ![]() Implementation by Matthias Mauch and Chris Cannam. System identifier – vamp:nnls-chroma:nnls-chroma The plugins are described below, starting with the most comprehensive first. NNLS Chroma analyses a single channel of audio using frame-wise spectral input from the Vamp host. The plugin was originally developed to extract treble and bass chromagrams for subsequent use in chord extraction methods. On this representation, two processing steps are performed: The spectrum is transformed to a log-frequency spectrum (constant-Q) with three bins per semitone. * tuning, after which each centre bin (i.e. bin 2, 5, 8, …) corresponds to a semitone, even if the tuning of the piece deviates from 440 Hz standard pitch. * running standardisation: subtraction of the running mean, division by the running standard deviation. The processed log-frequency spectrum is then used as an input for NNLS approximate transcription (using a dictionary of harmonic notes with geometrically decaying harmonics magnitudes). The output of the NNLS approximate transcription is semitone-spaced. To get the chroma, this semitone spectrum is multiplied (element-wise) with the desired profile (chroma or bass chroma) and then mapped to 12 bins. The resulting chroma frames can be normalised by (dividing by) their norm (L1, L2 and maximum norm available). Use approximate transcription (NNLS) (on or off default: on): toggle between NNLS approximate transcription and linear spectral mapping.spectral shape: (doesn't matter: no NNLS).use approximate transcription (NNLS): off.use approximate transcription (NNLS): on.The default settings (in brackets, below) are those used for Matthias Mauch’s 2010 MIREX submissions. Spectral roll-on (0 % - 5 % default: 0 %): this removes low-frequency noise - useful in quiet recordings. Consider the cumulative energy spectrum (from low to high frequencies). All bins below the first bin whose cumulative energy exceeds the quantile x will be set to 0. tuning mode (global or local default: global): local uses a local average for tuning, global uses all audio frames.Ī value of 0 means that no bins will be changed.Local tuning is only advisable when the tuning is likely to change over the audio, for example in podcasts, or in a cappella singing. spectral whitening (0.0 - 1.0 default: 1.0): determines how much the log-frequency spectrum is whitened.spectral shape (0.5 - 0.9 default: 0.7): the shape of the notes in the NNLS dictionary.įor values other than 0.0 the log-freq spectral bins are divided by ^, where “^” means “to the power of”.Their harmonic amplitude follows a geometrically decreasing pattern, in which the i-th harmonic has an amplitude of ^, where “^” means “to the power of”. #SONIC VISUALISER CHORDINO ALTERNATIVE MAC#.#SONIC VISUALISER CHORDINO ALTERNATIVE MAC OSX#.
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