/[svn]/linuxsampler/trunk/src/engines/gig/SmoothVolume.h
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Contents of /linuxsampler/trunk/src/engines/gig/SmoothVolume.h

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Revision 832 - (show annotations) (download) (as text)
Sun Feb 5 10:24:05 2006 UTC (18 years, 1 month ago) by persson
File MIME type: text/x-c++hdr
File size: 2847 byte(s)
* added smoothing of volume changes caused by control change messages
* fine tuning of the crossfade volume curve

1 /***************************************************************************
2 * *
3 * Copyright (C) 2006 Andreas Persson *
4 * *
5 * This program is free software; you can redistribute it and/or modify *
6 * it under the terms of the GNU General Public License as published by *
7 * the Free Software Foundation; either version 2 of the License, or *
8 * (at your option) any later version. *
9 * *
10 * This program is distributed in the hope that it will be useful, *
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
13 * GNU General Public License for more details. *
14 * *
15 * You should have received a copy of the GNU General Public License *
16 * along with this program; if not, write to the Free Software *
17 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
18 * MA 02110-1301 USA *
19 ***************************************************************************/
20
21 #ifndef __LS_GIG_SMOOTHVOLUME_H__
22 #define __LS_GIG_SMOOTHVOLUME_H__
23
24 namespace LinuxSampler { namespace gig {
25
26 /**
27 * Filter that smoothens out sudden changes in volume level.
28 */
29 class SmoothVolume {
30 public:
31
32 /**
33 * Initializes the smooth volume.
34 *
35 * @param volume - initial volume value
36 * @param sampleRate - rate at which the render function
37 * will be called
38 */
39 void trigger(float volume, float sampleRate);
40
41 /**
42 * Sets a new volume. The render function will return
43 * values gradually approaching this value.
44 *
45 * @param newVolume - new volume value
46 */
47 void update(float newVolume) {
48 goal = newVolume;
49 moving = true;
50 }
51
52 /**
53 * Calculates exactly one sample point of the volume
54 * curve.
55 *
56 * @returns next volume level
57 */
58 float render() { return moving ? process() : volume; }
59
60 private:
61 bool moving;
62 float goal;
63 float volume;
64 float coeff;
65 float decay;
66 float a1;
67 float b0;
68 float process();
69 };
70
71 }};
72 #endif

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