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 #ifndef DCPOMATIC_AUDIO_FILTER_H
21 #define DCPOMATIC_AUDIO_FILTER_H
23 #include <boost/shared_ptr.hpp>
27 struct audio_filter_impulse_input_test;
32 AudioFilter (float transition_bandwidth)
34 _M = 4 / transition_bandwidth;
40 boost::shared_ptr<AudioBuffers> run (boost::shared_ptr<const AudioBuffers> in);
45 friend struct audio_filter_impulse_kernel_test;
46 friend struct audio_filter_impulse_input_test;
48 std::vector<float> sinc_blackman (float cutoff, bool invert) const;
50 std::vector<float> _ir;
52 boost::shared_ptr<AudioBuffers> _tail;
55 class LowPassAudioFilter : public AudioFilter
58 /** Construct a windowed-sinc low-pass filter using the Blackman window.
59 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
60 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
62 LowPassAudioFilter (float transition_bandwidth, float cutoff);
65 class HighPassAudioFilter : public AudioFilter
68 /** Construct a windowed-sinc high-pass filter using the Blackman window.
69 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
70 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
72 HighPassAudioFilter (float transition_bandwidth, float cutoff);
75 class BandPassAudioFilter : public AudioFilter
78 /** Construct a windowed-sinc band-pass filter using the Blackman window.
79 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
80 * @param lower Lower cutoff frequency as a fraction of the sampling rate.
81 * @param higher Higher cutoff frequency as a fraction of the sampling rate.
83 BandPassAudioFilter (float transition_bandwidth, float lower, float higher);