/[svn]/linuxsampler/trunk/src/eg_vca.cpp
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Contents of /linuxsampler/trunk/src/eg_vca.cpp

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Revision 31 - (show annotations) (download)
Sun Jan 18 20:31:31 2004 UTC (16 years, 1 month ago) by schoenebeck
File size: 5020 byte(s)
* Added JACK support: Audio rendering process is now callback based and
  independant of used audio output system. Interfaces to other audio output
  systems can be added by creating a class derived from abstract base class
  'AudioIO' and embedding the new class into linuxsampler.cpp.
* src/audiothread.cpp: applied patch from Vladimir Senkov which fixes
  hanging notes in conjunction with the sustain pedal

1 /***************************************************************************
2 * *
3 * LinuxSampler - modular, streaming capable sampler *
4 * *
5 * Copyright (C) 2003 by Benno Senoner and Christian Schoenebeck *
6 * *
7 * This program is free software; you can redistribute it and/or modify *
8 * it under the terms of the GNU General Public License as published by *
9 * the Free Software Foundation; either version 2 of the License, or *
10 * (at your option) any later version. *
11 * *
12 * This program is distributed in the hope that it will be useful, *
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
15 * GNU General Public License for more details. *
16 * *
17 * You should have received a copy of the GNU General Public License *
18 * along with this program; if not, write to the Free Software *
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
20 * MA 02111-1307 USA *
21 ***************************************************************************/
22
23 #include "eg_vca.h"
24
25 EG_VCA::EG_VCA() {
26 Stage = stage_end;
27 Level = 0.0;
28 }
29
30 /**
31 * Will be called by the voice for every audio fragment to let the EG
32 * queue it's modulation changes for the current audio fragment.
33 */
34 void EG_VCA::Process(uint Samples) {
35 if (Stage == stage_sustain) return; // nothing to do
36
37 for (int to_process_total = Samples; to_process_total;) {
38 int iSample = 0;
39 switch (Stage) {
40 case stage_attack: {
41 int to_process = Min(to_process_total, AttackStepsLeft);
42 int process_end = iSample + to_process;
43 AttackStepsLeft -= to_process;
44 to_process_total -= to_process;
45 for (; iSample < process_end; iSample++) {
46 Level += AttackCoeff;
47 ModulationSystem::pDestinationParameter[ModulationSystem::destination_vca][iSample] *= Level;
48 }
49 if (!AttackStepsLeft) {
50 Stage = (ReleaseSignalReceived) ? stage_release : stage_sustain;
51 }
52 break;
53 }
54 case stage_sustain: {
55 return;
56 }
57 case stage_release: {
58 int process_end = iSample + to_process_total;
59 for (; iSample < process_end; iSample++) {
60 Level -= Level * ReleaseCoeff;
61 ModulationSystem::pDestinationParameter[ModulationSystem::destination_vca][iSample] *= Level;
62 }
63 if (Level <= EG_ENVELOPE_LIMIT) Stage = stage_end;
64 return;
65 }
66 case stage_end: {
67 int process_end = iSample + to_process_total;
68 for (; iSample < process_end; iSample++) {
69 ModulationSystem::pDestinationParameter[ModulationSystem::destination_vca][iSample] *= Level;
70 }
71 return;
72 }
73 }
74 }
75 }
76
77 /**
78 * Will be called by the voice when the key / voice was triggered.
79 *
80 * @param PreAttack - Preattack value for the envelope (0 - 1000 permille)
81 * @param AttackTime - Attack time for the envelope (0.000 - 60.000s)
82 * @param ReleaseTIme - Release time for the envelope (0.000 - 60.000s)
83 */
84 void EG_VCA::Trigger(uint PreAttack, double AttackTime, double ReleaseTime) {
85 ReleaseSignalReceived = false;
86 Stage = stage_attack;
87
88 // calculate attack stage parameters
89 AttackStepsLeft = (long) (AttackTime * ModulationSystem::GetSampleRate());
90 if (AttackStepsLeft) {
91 Level = PreAttack;
92 AttackCoeff = (1.0 - PreAttack) / AttackStepsLeft;
93 }
94 else {
95 Level = 1.0;
96 AttackCoeff = 0.0;
97 }
98
99 // calcuate release stage parameters
100 if (ReleaseTime < EG_MIN_RELEASE_TIME) ReleaseTime = EG_MIN_RELEASE_TIME; // to avoid click sounds at the end of the sample playback
101 ReleaseStepsLeft = (long) (ReleaseTime * ModulationSystem::GetSampleRate());
102 ReleaseCoeff = 1.0 - exp(log(EG_ENVELOPE_LIMIT) / (double) ReleaseStepsLeft);
103
104 dmsg(4,("AttackLength=%d, ReleaseLength=%d",AttackStepsLeft,ReleaseStepsLeft));
105 }
106
107 /**
108 * Will be called by the voice when the key / voice was released.
109 */
110 void EG_VCA::Release() {
111 // postpone release stage until sustain stage reached
112 if (Stage == stage_sustain) Stage = stage_release;
113 ReleaseSignalReceived = true;
114 }

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