3rdparty/SoundTouch/BPMDetect.h

////////////////////////////////////////////////////////////////////////////////
///
/// 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_
1	////////////////////////////////////////////////////////////////////////////////
2	///
3	/// Beats-per-minute (BPM) detection routine.
4	///
5	/// The beat detection algorithm works as follows:
6	/// - Use function 'inputSamples' to input a chunks of samples to the class for
7	/// analysis. It's a good idea to enter a large sound file or stream in smallish
8	/// chunks of around few kilosamples in order not to extinguish too much RAM memory.
9	/// - Input sound data is decimated to approx 500 Hz to reduce calculation burden,
10	/// which is basically ok as low (bass) frequencies mostly determine the beat rate.
11	/// Simple averaging is used for anti-alias filtering because the resulting signal
12	/// quality isn't of that high importance.
13	/// - Decimated sound data is enveloped, i.e. the amplitude shape is detected by
14	/// taking absolute value that's smoothed by sliding average. Signal levels that
15	/// are below a couple of times the general RMS amplitude level are cut away to
16	/// leave only notable peaks there.
17	/// - Repeating sound patterns (e.g. beats) are detected by calculating short-term
18	/// autocorrelation function of the enveloped signal.
19	/// - After whole sound data file has been analyzed as above, the bpm level is
20	/// detected by function 'getBpm' that finds the highest peak of the autocorrelation
21	/// function, calculates it's precise location and converts this reading to bpm's.
22	///
23	/// Author : Copyright (c) Olli Parviainen
24	/// Author e-mail : oparviai 'at' iki.fi
25	/// SoundTouch WWW: http://www.surina.net/soundtouch
26	///
27	////////////////////////////////////////////////////////////////////////////////
28	//
29	// Last changed : $Date: 2009-02-21 18:00:14 +0200 (Sat, 21 Feb 2009) $
30	// File revision : $Revision: 4 $
31	//
32	// $Id: BPMDetect.h 63 2009-02-21 16:00:14Z oparviai $
33	//
34	////////////////////////////////////////////////////////////////////////////////
35	//
36	// License :
37	//
38	// SoundTouch audio processing library
39	// Copyright (c) Olli Parviainen
40	//
41	// This library is free software; you can redistribute it and/or
42	// modify it under the terms of the GNU Lesser General Public
43	// License as published by the Free Software Foundation; either
44	// version 2.1 of the License, or (at your option) any later version.
45	//
46	// This library is distributed in the hope that it will be useful,
47	// but WITHOUT ANY WARRANTY; without even the implied warranty of
48	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
49	// Lesser General Public License for more details.
50	//
51	// You should have received a copy of the GNU Lesser General Public
52	// License along with this library; if not, write to the Free Software
53	// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
54	//
55	////////////////////////////////////////////////////////////////////////////////
56
57	#ifndef _BPMDetect_H_
58	#define _BPMDetect_H_
59
60	#include "STTypes.h"
61	#include "FIFOSampleBuffer.h"
62
63	namespace soundtouch
64	{
65
66	/// Minimum allowed BPM rate. Used to restrict accepted result above a reasonable limit.
67	#define MIN_BPM 29
68
69	/// Maximum allowed BPM rate. Used to restrict accepted result below a reasonable limit.
70	#define MAX_BPM 230
71
72
73	/// Class for calculating BPM rate for audio data.
74	class BPMDetect
75	{
76	protected:
77	/// Auto-correlation accumulator bins.
78	float *xcorr;
79
80	/// Amplitude envelope sliding average approximation level accumulator
81	float envelopeAccu;
82
83	/// RMS volume sliding average approximation level accumulator
84	float RMSVolumeAccu;
85
86	/// Sample average counter.
87	int decimateCount;
88
89	/// Sample average accumulator for FIFO-like decimation.
90	soundtouch::LONG_SAMPLETYPE decimateSum;
91
92	/// Decimate sound by this coefficient to reach approx. 500 Hz.
93	int decimateBy;
94
95	/// Auto-correlation window length
96	int windowLen;
97
98	/// Number of channels (1 = mono, 2 = stereo)
99	int channels;
100
101	/// sample rate
102	int sampleRate;
103
104	/// Beginning of auto-correlation window: Autocorrelation isn't being updated for
105	/// the first these many correlation bins.
106	int windowStart;
107
108	/// FIFO-buffer for decimated processing samples.
109	soundtouch::FIFOSampleBuffer *buffer;
110
111	/// Updates auto-correlation function for given number of decimated samples that
112	/// are read from the internal 'buffer' pipe (samples aren't removed from the pipe
113	/// though).
114	void updateXCorr(int process_samples /// How many samples are processed.
115	);
116
117	/// Decimates samples to approx. 500 Hz.
118	///
119	/// \return Number of output samples.
120	int decimate(soundtouch::SAMPLETYPE *dest, ///< Destination buffer
121	const soundtouch::SAMPLETYPE *src, ///< Source sample buffer
122	int numsamples ///< Number of source samples.
123	);
124
125	/// Calculates amplitude envelope for the buffer of samples.
126	/// Result is output to 'samples'.
127	void calcEnvelope(soundtouch::SAMPLETYPE *samples, ///< Pointer to input/output data buffer
128	int numsamples ///< Number of samples in buffer
129	);
130
131	public:
132	/// Constructor.
133	BPMDetect(int numChannels, ///< Number of channels in sample data.
134	int sampleRate ///< Sample rate in Hz.
135	);
136
137	/// Destructor.
138	virtual ~BPMDetect();
139
140	/// Inputs a block of samples for analyzing: Envelopes the samples and then
141	/// updates the autocorrelation estimation. When whole song data has been input
142	/// in smaller blocks using this function, read the resulting bpm with 'getBpm'
143	/// function.
144	///
145	/// Notice that data in 'samples' array can be disrupted in processing.
146	void inputSamples(const soundtouch::SAMPLETYPE *samples, ///< Pointer to input/working data buffer
147	int numSamples ///< Number of samples in buffer
148	);
149
150
151	/// Analyzes the results and returns the BPM rate. Use this function to read result
152	/// after whole song data has been input to the class by consecutive calls of
153	/// 'inputSamples' function.
154	///
155	/// \return Beats-per-minute rate, or zero if detection failed.
156	float getBpm();
157	};
158
159	}
160
161	#endif // _BPMDetect_H_