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Diffstat (limited to 'plugins/dsp_soundtouch/soundtouch/include/BPMDetect.h')
| -rw-r--r-- | plugins/dsp_soundtouch/soundtouch/include/BPMDetect.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/plugins/dsp_soundtouch/soundtouch/include/BPMDetect.h b/plugins/dsp_soundtouch/soundtouch/include/BPMDetect.h new file mode 100644 index 00000000..4def43f1 --- /dev/null +++ b/plugins/dsp_soundtouch/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_
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