From 8adfb3bd99b4dcff2459756af090a640fd7a4b4a Mon Sep 17 00:00:00 2001 From: yo mama Date: Fri, 19 Jun 2015 16:24:27 -0400 Subject: clone --- pysoundtouch/soundtouch/include/BPMDetect.h | 161 ++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 pysoundtouch/soundtouch/include/BPMDetect.h (limited to 'pysoundtouch/soundtouch/include/BPMDetect.h') diff --git a/pysoundtouch/soundtouch/include/BPMDetect.h b/pysoundtouch/soundtouch/include/BPMDetect.h new file mode 100644 index 0000000..4def43f --- /dev/null +++ b/pysoundtouch/soundtouch/include/BPMDetect.h @@ -0,0 +1,161 @@ +//////////////////////////////////////////////////////////////////////////////// +/// +/// Beats-per-minute (BPM) detection routine. +/// +/// The beat detection algorithm works as follows: +/// - Use function 'inputSamples' to input a chunks of samples to the class for +/// analysis. It's a good idea to enter a large sound file or stream in smallish +/// chunks of around few kilosamples in order not to extinguish too much RAM memory. +/// - Input sound data is decimated to approx 500 Hz to reduce calculation burden, +/// which is basically ok as low (bass) frequencies mostly determine the beat rate. +/// Simple averaging is used for anti-alias filtering because the resulting signal +/// quality isn't of that high importance. +/// - Decimated sound data is enveloped, i.e. the amplitude shape is detected by +/// taking absolute value that's smoothed by sliding average. Signal levels that +/// are below a couple of times the general RMS amplitude level are cut away to +/// leave only notable peaks there. +/// - Repeating sound patterns (e.g. beats) are detected by calculating short-term +/// autocorrelation function of the enveloped signal. +/// - After whole sound data file has been analyzed as above, the bpm level is +/// detected by function 'getBpm' that finds the highest peak of the autocorrelation +/// function, calculates it's precise location and converts this reading to bpm's. +/// +/// Author : Copyright (c) Olli Parviainen +/// Author e-mail : oparviai 'at' iki.fi +/// SoundTouch WWW: http://www.surina.net/soundtouch +/// +//////////////////////////////////////////////////////////////////////////////// +// +// Last changed : $Date: 2009-02-21 18:00:14 +0200 (Sat, 21 Feb 2009) $ +// File revision : $Revision: 4 $ +// +// $Id: BPMDetect.h 63 2009-02-21 16:00:14Z oparviai $ +// +//////////////////////////////////////////////////////////////////////////////// +// +// License : +// +// SoundTouch audio processing library +// Copyright (c) Olli Parviainen +// +// This library is free software; you can redistribute it and/or +// modify it under the terms of the GNU Lesser General Public +// License as published by the Free Software Foundation; either +// version 2.1 of the License, or (at your option) any later version. +// +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public +// License along with this library; if not, write to the Free Software +// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +// +//////////////////////////////////////////////////////////////////////////////// + +#ifndef _BPMDetect_H_ +#define _BPMDetect_H_ + +#include "STTypes.h" +#include "FIFOSampleBuffer.h" + +namespace soundtouch +{ + +/// Minimum allowed BPM rate. Used to restrict accepted result above a reasonable limit. +#define MIN_BPM 29 + +/// Maximum allowed BPM rate. Used to restrict accepted result below a reasonable limit. +#define MAX_BPM 230 + + +/// Class for calculating BPM rate for audio data. +class BPMDetect +{ +protected: + /// Auto-correlation accumulator bins. + float *xcorr; + + /// Amplitude envelope sliding average approximation level accumulator + float envelopeAccu; + + /// RMS volume sliding average approximation level accumulator + float RMSVolumeAccu; + + /// Sample average counter. + int decimateCount; + + /// Sample average accumulator for FIFO-like decimation. + soundtouch::LONG_SAMPLETYPE decimateSum; + + /// Decimate sound by this coefficient to reach approx. 500 Hz. + int decimateBy; + + /// Auto-correlation window length + int windowLen; + + /// Number of channels (1 = mono, 2 = stereo) + int channels; + + /// sample rate + int sampleRate; + + /// Beginning of auto-correlation window: Autocorrelation isn't being updated for + /// the first these many correlation bins. + int windowStart; + + /// FIFO-buffer for decimated processing samples. + soundtouch::FIFOSampleBuffer *buffer; + + /// Updates auto-correlation function for given number of decimated samples that + /// are read from the internal 'buffer' pipe (samples aren't removed from the pipe + /// though). + void updateXCorr(int process_samples /// How many samples are processed. + ); + + /// Decimates samples to approx. 500 Hz. + /// + /// \return Number of output samples. + int decimate(soundtouch::SAMPLETYPE *dest, ///< Destination buffer + const soundtouch::SAMPLETYPE *src, ///< Source sample buffer + int numsamples ///< Number of source samples. + ); + + /// Calculates amplitude envelope for the buffer of samples. + /// Result is output to 'samples'. + void calcEnvelope(soundtouch::SAMPLETYPE *samples, ///< Pointer to input/output data buffer + int numsamples ///< Number of samples in buffer + ); + +public: + /// Constructor. + BPMDetect(int numChannels, ///< Number of channels in sample data. + int sampleRate ///< Sample rate in Hz. + ); + + /// Destructor. + virtual ~BPMDetect(); + + /// Inputs a block of samples for analyzing: Envelopes the samples and then + /// updates the autocorrelation estimation. When whole song data has been input + /// in smaller blocks using this function, read the resulting bpm with 'getBpm' + /// function. + /// + /// Notice that data in 'samples' array can be disrupted in processing. + void inputSamples(const soundtouch::SAMPLETYPE *samples, ///< Pointer to input/working data buffer + int numSamples ///< Number of samples in buffer + ); + + + /// Analyzes the results and returns the BPM rate. Use this function to read result + /// after whole song data has been input to the class by consecutive calls of + /// 'inputSamples' function. + /// + /// \return Beats-per-minute rate, or zero if detection failed. + float getBpm(); +}; + +} + +#endif // _BPMDetect_H_ -- cgit v1.2.3-70-g09d2