dep: Add soundtouch

dep/soundtouch/include/BPMDetect.h

@@ -0,0 +1,205 @@
+////////////////////////////////////////////////////////////////////////////////
+///
+/// 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
+///
+////////////////////////////////////////////////////////////////////////////////
+//
+// 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 <vector>
+#include "STTypes.h"
+#include "FIFOSampleBuffer.h"
+
+namespace soundtouch
+{
+
+    /// Minimum allowed BPM rate. Used to restrict accepted result above a reasonable limit.
+    #define MIN_BPM 45
+
+    /// Maximum allowed BPM rate range. Used for calculating algorithm parametrs
+    #define MAX_BPM_RANGE 200
+
+    /// Maximum allowed BPM rate range. Used to restrict accepted result below a reasonable limit.
+    #define MAX_BPM_VALID 190
+
+////////////////////////////////////////////////////////////////////////////////
+
+    typedef struct
+    {
+        float pos;
+        float strength;
+    } BEAT;
+
+
+    class IIR2_filter
+    {
+        double coeffs[5];
+        double prev[5];
+
+    public:
+        IIR2_filter(const double *lpf_coeffs);
+        float update(float x);
+    };
+
+
+    /// Class for calculating BPM rate for audio data.
+    class BPMDetect
+    {
+    protected:
+        /// Auto-correlation accumulator bins.
+        float *xcorr;
+
+        /// 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;
+
+        /// window functions for data preconditioning
+        float *hamw;
+        float *hamw2;
+
+        // beat detection variables
+        int pos;
+        int peakPos;
+        int beatcorr_ringbuffpos;
+        int init_scaler;
+        float peakVal;
+        float *beatcorr_ringbuff;
+
+        /// FIFO-buffer for decimated processing samples.
+        soundtouch::FIFOSampleBuffer *buffer;
+
+        /// Collection of detected beat positions
+        //BeatCollection beats;
+        std::vector<BEAT> beats;
+
+        // 2nd order low-pass-filter
+        IIR2_filter beat_lpf;
+
+        /// 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
+        );
+
+        /// remove constant bias from xcorr data
+        void removeBias();
+
+        // Detect individual beat positions
+        void updateBeatPos(int process_samples);
+
+
+    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();
+
+        /// Get beat position arrays. Note: The array includes also really low beat detection values 
+        /// in absence of clear strong beats. Consumer may wish to filter low values away.
+        /// - "pos" receive array of beat positions
+        /// - "values" receive array of beat detection strengths
+        /// - max_num indicates max.size of "pos" and "values" array.  
+        ///
+        /// You can query a suitable array sized by calling this with NULL in "pos" & "values".
+        ///
+        /// \return number of beats in the arrays.
+        int getBeats(float *pos, float *strength, int max_num);
+    };
+}
+#endif // _BPMDetect_H_