1 #ifndef STK_PRCREV_H
2 #define STK_PRCREV_H
3
4 #include "Effect.h"
5 #include "Delay.h"
6
7 namespace stk {
8
9 /***************************************************/
10 /*! \class PRCRev
11 \brief Perry's simple reverberator class.
12
13 This class takes a monophonic input signal and produces a stereo
14 output signal. It is based on some of the famous Stanford/CCRMA
15 reverbs (NRev, KipRev), which were based on the
16 Chowning/Moorer/Schroeder reverberators using networks of simple
17 allpass and comb delay filters. This class implements two series
18 allpass units and two parallel comb filters.
19
20 by Perry R. Cook and Gary P. Scavone, 1995--2021.
21 */
22 /***************************************************/
23
24 class PRCRev : public Effect
25 {
26 public:
27 //! Class constructor taking a T60 decay time argument (one second default value).
28 PRCRev( StkFloat T60 = 1.0 );
29
30 //! Reset and clear all internal state.
31 void clear( void );
32
33 //! Set the reverberation T60 decay time.
34 void setT60( StkFloat T60 );
35
36 //! Return the specified channel value of the last computed stereo frame.
37 /*!
38 Use the lastFrame() function to get both values of the last
39 computed stereo frame. The \c channel argument must be 0 or 1
40 (the first channel is specified by 0). However, range checking is
41 only performed if _STK_DEBUG_ is defined during compilation, in
42 which case an out-of-range value will trigger an StkError
43 exception.
44 */
45 StkFloat lastOut( unsigned int channel = 0 );
46
47 //! Input one sample to the effect and return the specified \c channel value of the computed stereo frame.
48 /*!
49 Use the lastFrame() function to get both values of the computed
50 stereo output frame. The \c channel argument must be 0 or 1 (the
51 first channel is specified by 0). However, range checking is only
52 performed if _STK_DEBUG_ is defined during compilation, in which
53 case an out-of-range value will trigger an StkError exception.
54 */
55 StkFloat tick( StkFloat input, unsigned int channel = 0 );
56
57 //! Take a channel of the StkFrames object as inputs to the effect and replace with stereo outputs.
58 /*!
59 The StkFrames argument reference is returned. The stereo
60 outputs are written to the StkFrames argument starting at the
61 specified \c channel. Therefore, the \c channel argument must be
62 less than ( channels() - 1 ) of the StkFrames argument (the first
63 channel is specified by 0). However, range checking is only
64 performed if _STK_DEBUG_ is defined during compilation, in which
65 case an out-of-range value will trigger an StkError exception.
66 */
67 StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
68
69 //! Take a channel of the \c iFrames object as inputs to the effect and write stereo outputs to the \c oFrames object.
70 /*!
71 The \c iFrames object reference is returned. The \c iChannel
72 argument must be less than the number of channels in the \c
73 iFrames argument (the first channel is specified by 0). The \c
74 oChannel argument must be less than ( channels() - 1 ) of the \c
75 oFrames argument. However, range checking is only performed if
76 _STK_DEBUG_ is defined during compilation, in which case an
77 out-of-range value will trigger an StkError exception.
78 */
79 StkFrames& tick( StkFrames& iFrames, StkFrames &oFrames, unsigned int iChannel = 0, unsigned int oChannel = 0 );
80
81 protected:
82
83 Delay allpassDelays_[2];
84 Delay combDelays_[2];
85 StkFloat allpassCoefficient_;
86 StkFloat combCoefficient_[2];
87
88 };
89
lastOut(unsigned int channel)90 inline StkFloat PRCRev :: lastOut( unsigned int channel )
91 {
92 #if defined(_STK_DEBUG_)
93 if ( channel > 1 ) {
94 oStream_ << "PRCRev::lastOut(): channel argument must be less than 2!";
95 handleError( StkError::FUNCTION_ARGUMENT );
96 }
97 #endif
98
99 return lastFrame_[channel];
100 }
101
tick(StkFloat input,unsigned int channel)102 inline StkFloat PRCRev :: tick( StkFloat input, unsigned int channel )
103 {
104 #if defined(_STK_DEBUG_)
105 if ( channel > 1 ) {
106 oStream_ << "PRCRev::tick(): channel argument must be less than 2!";
107 handleError( StkError::FUNCTION_ARGUMENT );
108 }
109 #endif
110
111 StkFloat temp, temp0, temp1, temp2, temp3;
112
113 temp = allpassDelays_[0].lastOut();
114 temp0 = allpassCoefficient_ * temp;
115 temp0 += input;
116 allpassDelays_[0].tick(temp0);
117 temp0 = -(allpassCoefficient_ * temp0) + temp;
118
119 temp = allpassDelays_[1].lastOut();
120 temp1 = allpassCoefficient_ * temp;
121 temp1 += temp0;
122 allpassDelays_[1].tick(temp1);
123 temp1 = -(allpassCoefficient_ * temp1) + temp;
124
125 temp2 = temp1 + ( combCoefficient_[0] * combDelays_[0].lastOut() );
126 temp3 = temp1 + ( combCoefficient_[1] * combDelays_[1].lastOut() );
127
128 lastFrame_[0] = effectMix_ * (combDelays_[0].tick(temp2));
129 lastFrame_[1] = effectMix_ * (combDelays_[1].tick(temp3));
130 temp = (1.0 - effectMix_) * input;
131 lastFrame_[0] += temp;
132 lastFrame_[1] += temp;
133
134 return lastFrame_[channel];
135 }
136
137 } // stk namespace
138
139 #endif
140
141