2 Copyright (C) 2014 Carl Hetherington <cth@carlh.net>
4 This file is part of DCP-o-matic.
6 DCP-o-matic is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 DCP-o-matic is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with DCP-o-matic. If not, see <http://www.gnu.org/licenses/>.
21 #ifndef DCPOMATIC_AUDIO_FILTER_H
22 #define DCPOMATIC_AUDIO_FILTER_H
24 #include <boost/shared_ptr.hpp>
27 struct audio_filter_impulse_input_test;
29 /** An audio filter which can take AudioBuffers and apply some filtering operation,
30 * returning filtered samples
35 explicit AudioFilter (float transition_bandwidth)
38 _M = 4 / transition_bandwidth;
44 virtual ~AudioFilter ();
46 boost::shared_ptr<AudioBuffers> run (boost::shared_ptr<const AudioBuffers> in);
51 friend struct audio_filter_impulse_kernel_test;
52 friend struct audio_filter_impulse_input_test;
54 float* sinc_blackman (float cutoff, bool invert) const;
58 boost::shared_ptr<AudioBuffers> _tail;
61 class LowPassAudioFilter : public AudioFilter
64 /** Construct a windowed-sinc low-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 LowPassAudioFilter (float transition_bandwidth, float cutoff);
71 class HighPassAudioFilter : public AudioFilter
74 /** Construct a windowed-sinc high-pass filter using the Blackman window.
75 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
76 * @param cutoff Cutoff frequency as a fraction of the sampling rate.
78 HighPassAudioFilter (float transition_bandwidth, float cutoff);
81 class BandPassAudioFilter : public AudioFilter
84 /** Construct a windowed-sinc band-pass filter using the Blackman window.
85 * @param transition_bandwidth Transition bandwidth as a fraction of the sampling rate.
86 * @param lower Lower cutoff frequency as a fraction of the sampling rate.
87 * @param higher Higher cutoff frequency as a fraction of the sampling rate.
89 BandPassAudioFilter (float transition_bandwidth, float lower, float higher);