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92 lines
2.9 KiB
C++
92 lines
2.9 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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///
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/// Sampled sound tempo changer/time stretch algorithm. Changes the sound tempo
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/// while maintaining the original pitch by using a time domain WSOLA-like method
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/// with several performance-increasing tweaks.
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///
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/// Anti-alias filter is used to prevent folding of high frequencies when
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/// transposing the sample rate with interpolation.
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///
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/// Author : Copyright (c) Olli Parviainen
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/// Author e-mail : oparviai 'at' iki.fi
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/// SoundTouch WWW: http://www.surina.net/soundtouch
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///
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////////////////////////////////////////////////////////////////////////////////
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//
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// Last changed : $Date$
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// File revision : $Revision: 4 $
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//
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// $Id$
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//
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////////////////////////////////////////////////////////////////////////////////
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//
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// License :
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//
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// SoundTouch audio processing library
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// Copyright (c) Olli Parviainen
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//
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////////////////////////////////////////////////////////////////////////////////
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#ifndef AAFilter_H
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#define AAFilter_H
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#include "STTypes.h"
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namespace soundtouch
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{
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class AAFilter
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{
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protected:
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class FIRFilter *pFIR;
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/// Low-pass filter cut-off frequency, negative = invalid
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double cutoffFreq;
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/// num of filter taps
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uint length;
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/// Calculate the FIR coefficients realizing the given cutoff-frequency
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void calculateCoeffs();
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public:
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AAFilter(uint length);
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~AAFilter();
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/// Sets new anti-alias filter cut-off edge frequency, scaled to sampling
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/// frequency (nyquist frequency = 0.5). The filter will cut off the
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/// frequencies than that.
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void setCutoffFreq(double newCutoffFreq);
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/// Sets number of FIR filter taps, i.e. ~filter complexity
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void setLength(uint newLength);
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uint getLength() const;
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/// Applies the filter to the given sequence of samples.
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/// Note : The amount of outputted samples is by value of 'filter length'
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/// smaller than the amount of input samples.
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uint evaluate(SAMPLETYPE *dest,
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const SAMPLETYPE *src,
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uint numSamples,
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uint numChannels) const;
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};
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}
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#endif
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