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comparison: media/libsoundtouch/src/AAFilter.h
media/libsoundtouch/src/AAFilter.h
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| 1 //////////////////////////////////////////////////////////////////////////////// | |
| 2 /// | |
| 3 /// Sampled sound tempo changer/time stretch algorithm. Changes the sound tempo | |
| 4 /// while maintaining the original pitch by using a time domain WSOLA-like method | |
| 5 /// with several performance-increasing tweaks. | |
| 6 /// | |
| 7 /// Anti-alias filter is used to prevent folding of high frequencies when | |
| 8 /// transposing the sample rate with interpolation. | |
| 9 /// | |
| 10 /// Author : Copyright (c) Olli Parviainen | |
| 11 /// Author e-mail : oparviai 'at' iki.fi | |
| 12 /// SoundTouch WWW: http://www.surina.net/soundtouch | |
| 13 /// | |
| 14 //////////////////////////////////////////////////////////////////////////////// | |
| 15 // | |
| 16 // Last changed : $Date: 2014-01-07 13:41:23 -0600 (Tue, 07 Jan 2014) $ | |
| 17 // File revision : $Revision: 4 $ | |
| 18 // | |
| 19 // $Id: AAFilter.h 187 2014-01-07 19:41:23Z oparviai $ | |
| 20 // | |
| 21 //////////////////////////////////////////////////////////////////////////////// | |
| 22 // | |
| 23 // License : | |
| 24 // | |
| 25 // SoundTouch audio processing library | |
| 26 // Copyright (c) Olli Parviainen | |
| 27 // | |
| 28 // This library is free software; you can redistribute it and/or | |
| 29 // modify it under the terms of the GNU Lesser General Public | |
| 30 // License as published by the Free Software Foundation; either | |
| 31 // version 2.1 of the License, or (at your option) any later version. | |
| 32 // | |
| 33 // This library is distributed in the hope that it will be useful, | |
| 34 // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 35 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 36 // Lesser General Public License for more details. | |
| 37 // | |
| 38 // You should have received a copy of the GNU Lesser General Public | |
| 39 // License along with this library; if not, write to the Free Software | |
| 40 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 41 // | |
| 42 //////////////////////////////////////////////////////////////////////////////// | |
| 43 | |
| 44 #ifndef AAFilter_H | |
| 45 #define AAFilter_H | |
| 46 | |
| 47 #include "STTypes.h" | |
| 48 #include "FIFOSampleBuffer.h" | |
| 49 | |
| 50 namespace soundtouch | |
| 51 { | |
| 52 | |
| 53 class AAFilter | |
| 54 { | |
| 55 protected: | |
| 56 class FIRFilter *pFIR; | |
| 57 | |
| 58 /// Low-pass filter cut-off frequency, negative = invalid | |
| 59 double cutoffFreq; | |
| 60 | |
| 61 /// num of filter taps | |
| 62 uint length; | |
| 63 | |
| 64 /// Calculate the FIR coefficients realizing the given cutoff-frequency | |
| 65 void calculateCoeffs(); | |
| 66 public: | |
| 67 AAFilter(uint length); | |
| 68 | |
| 69 ~AAFilter(); | |
| 70 | |
| 71 /// Sets new anti-alias filter cut-off edge frequency, scaled to sampling | |
| 72 /// frequency (nyquist frequency = 0.5). The filter will cut off the | |
| 73 /// frequencies than that. | |
| 74 void setCutoffFreq(double newCutoffFreq); | |
| 75 | |
| 76 /// Sets number of FIR filter taps, i.e. ~filter complexity | |
| 77 void setLength(uint newLength); | |
| 78 | |
| 79 uint getLength() const; | |
| 80 | |
| 81 /// Applies the filter to the given sequence of samples. | |
| 82 /// Note : The amount of outputted samples is by value of 'filter length' | |
| 83 /// smaller than the amount of input samples. | |
| 84 uint evaluate(SAMPLETYPE *dest, | |
| 85 const SAMPLETYPE *src, | |
| 86 uint numSamples, | |
| 87 uint numChannels) const; | |
| 88 | |
| 89 /// Applies the filter to the given src & dest pipes, so that processed amount of | |
| 90 /// samples get removed from src, and produced amount added to dest | |
| 91 /// Note : The amount of outputted samples is by value of 'filter length' | |
| 92 /// smaller than the amount of input samples. | |
| 93 uint evaluate(FIFOSampleBuffer &dest, | |
| 94 FIFOSampleBuffer &src) const; | |
| 95 | |
| 96 }; | |
| 97 | |
| 98 } | |
| 99 | |
| 100 #endif |
