LogSpectrum¶

streaming mode | Spectral category

Inputs¶

spectrum (vector_real) - spectrum frame

Outputs¶

logFreqSpectrum (vector_real) - log frequency spectrum frame

meanTuning (vector_real) - normalized mean tuning frequency

localTuning (real) - normalized local tuning frequency

Parameters¶

binsPerSemitone (real ∈ (0, ∞), default = 3) :
bins per semitone

frameSize (integer ∈ (1, ∞), default = 1025) :
the input frame size of the spectrum vector

nOctave (integer ∈ (0, 10), default = 7) :
the number of octave of the output vector

rollOn (real ∈ [0, 5], default = 0) :
this removes low-frequency noise - useful in quiet recordings

sampleRate (real ∈ (0, ∞), default = 44100) :
the input sample rate

Description¶

This algorithm computes spectrum with logarithmically distributed frequency bins. This code is ported from NNLS Chroma [1, 2].This algorithm also returns a local tuning that is retrieved for input frame and a global tuning that is updated with a moving average.

Note: As the algorithm uses moving averages that are updated every frame it should be reset before processing a new audio file. To do this call reset() (or configure())

References:: [1] Mauch, M., & Dixon, S. (2010, August). Approximate Note Transcription for the Improved Identification of Difficult Chords. In ISMIR (pp. 135-140). [2] Chordino and NNLS Chroma, http://www.isophonics.net/nnls-chroma

Source code¶

C++ source code

C++ header file