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.
21 #include <boost/shared_ptr.hpp>
24 class audio_filter_impulse_kernel_test;
25 class audio_filter_impulse_input_test;
30 AudioFilter (float transition_bandwidth)
32 _M = 4 / transition_bandwidth;
38 boost::shared_ptr<AudioBuffers> run (boost::shared_ptr<AudioBuffers> in);
41 friend class audio_filter_impulse_kernel_test;
42 friend class audio_filter_impulse_input_test;
44 std::vector<float> sinc_blackman (float cutoff, bool invert) const;
46 std::vector<float> _ir;
48 boost::shared_ptr<AudioBuffers> _tail;
51 class LowPassAudioFilter : public AudioFilter
54 /** Construct a windowed-sinc low-pass filter using the Blackman window.
55 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
56 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
58 LowPassAudioFilter (float transition_bandwidth, float cutoff);
61 class HighPassAudioFilter : public AudioFilter
64 /** Construct a windowed-sinc high-pass filter using the Blackman window.
65 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
66 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
68 HighPassAudioFilter (float transition_bandwidth, float cutoff);
71 class BandPassAudioFilter : public AudioFilter
74 /** Construct a windowed-sinc band-pass filter using the Blackman window.
75 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
76 * @param lower Lower cutoff frequency as a fraction of the sampling rate.
77 * @param higher Higher cutoff frequency as a fraction of the sampling rate.
79 BandPassAudioFilter (float transition_bandwidth, float lower, float higher);