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1
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2 Constant-Q Library
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3 ==================
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4
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5 A C++ library and Vamp plugin implementing the Constant-Q transform
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6 of a time-domain signal.
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7
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8 https://code.soundsoftware.ac.uk/projects/constant-q-cpp
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9
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10 The Constant-Q transform is a time-to-frequency-domain transform
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11 related to the short-time Fourier transform, but with output bins
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12 spaced logarithmically in frequency, rather than linearly. The output
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13 bins are therefore linearly spaced in terms of musical pitch.
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14
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15 This library provides:
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16
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17 * Forward transform: time-domain to complex Constant-Q bins
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18 * Forward spectrogram: time-domain to interpolated Constant-Q
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19 magnitude spectrogram
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20 * Inverse transform: complex Constant-Q bins to time domain
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21
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22 The Vamp plugin provides:
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23
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24 * Constant-Q magnitude spectrogram with high and low frequency
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25 extents defined in Hz
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26 * Constant-Q magnitude spectrogram with high and low frequency
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27 extents defined as MIDI pitch values
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28 * Pitch chromagram obtained by folding a Constant-Q spectrogram
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29 around into a single-octave range
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30
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31 The method is drawn from Christian Schörkhuber and Anssi Klapuri,
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32 "Constant-Q transform toolbox for music processing", SMC 2010. See the
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33 file CITATION for details. If you use this code in research work,
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34 please cite this paper.
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35
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36 The implementation is reasonably fast and is causal, operating
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37 block-by-block on the input, though with quite high latency
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38 depending on the frequency range specified. By default it produces
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39 output at a higher time resolution than some other implementations,
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40 using multiple kernel atoms per time block. The inverse transform is
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41 approximate rather than exact (see the paper for details).
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42
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43 The C++ implementation is by Chris Cannam, Copyright 2014 Queen Mary,
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44 University of London.
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45
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46 The library is provided under a liberal BSD/MIT-style open source
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47 licence. See the file COPYING for more information.
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48
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