2 Copyright (C) 2014 Carl Hetherington <cth@carlh.net>
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #include <boost/shared_ptr.hpp>
24 struct audio_filter_impulse_input_test;
29 AudioFilter (float transition_bandwidth)
31 _M = 4 / transition_bandwidth;
37 boost::shared_ptr<AudioBuffers> run (boost::shared_ptr<AudioBuffers> in);
42 friend struct audio_filter_impulse_kernel_test;
43 friend struct audio_filter_impulse_input_test;
45 std::vector<float> sinc_blackman (float cutoff, bool invert) const;
47 std::vector<float> _ir;
49 boost::shared_ptr<AudioBuffers> _tail;
52 class LowPassAudioFilter : public AudioFilter
55 /** Construct a windowed-sinc low-pass filter using the Blackman window.
56 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
57 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
59 LowPassAudioFilter (float transition_bandwidth, float cutoff);
62 class HighPassAudioFilter : public AudioFilter
65 /** Construct a windowed-sinc high-pass filter using the Blackman window.
66 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
67 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
69 HighPassAudioFilter (float transition_bandwidth, float cutoff);
72 class BandPassAudioFilter : public AudioFilter
75 /** Construct a windowed-sinc band-pass filter using the Blackman window.
76 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
77 * @param lower Lower cutoff frequency as a fraction of the sampling rate.
78 * @param higher Higher cutoff frequency as a fraction of the sampling rate.
80 BandPassAudioFilter (float transition_bandwidth, float lower, float higher);