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# stk::Echo Class Reference

STK echo effect class. More...

`#include <Echo.h>`

Inheritance diagram for stk::Echo:

List of all members.

## Public Member Functions
| Echo (unsigned long maximumDelay=(unsigned long) Stk::sampleRate())
| Class constructor, taking the longest desired delay length (one second default value).
void | clear ()
| Reset and clear all internal state.
void | setMaximumDelay (unsigned long delay)
| Set the maximum delay line length in samples.
void | setDelay (unsigned long delay)
| Set the delay line length in samples.
StkFloat | lastOut (void) const
| Return the last computed output value.
StkFloat | tick (StkFloat input)
| Input one sample to the effect and return one output.
StkFrames & | tick (StkFrames &frames, unsigned int channel=0)
| Take a channel of the StkFrames object as inputs to the effect and replace with corresponding outputs.
StkFrames & | tick (StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)
| Take a channel of the `iFrames` object as inputs to the effect and write outputs to the `oFrames` object.

## Detailed Description

STK echo effect class.

This class implements an echo effect.

by Perry R. Cook and Gary P. Scavone, 1995-2012.

## Constructor & Destructor Documentation

stk::Echo::Echo | ( | unsigned long | maximumDelay = `(unsigned long) Stk::sampleRate()` | ) |

Class constructor, taking the longest desired delay length (one second default value).

The default delay value is set to 1/2 the maximum delay length.

## Member Function Documentation

StkFrames & stk::Echo::tick | ( | StkFrames & | frames,
|  | unsigned int | channel = `0` |
| ) |  |  | `[inline]`

Take a channel of the StkFrames object as inputs to the effect and replace with corresponding outputs.

The StkFrames argument reference is returned. The `channel` argument must be less than the number of channels in the StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

    00079 {
    00080 #if defined(_STK_DEBUG_)
    00081   if ( channel >= frames.channels() ) {
    00082     oStream_ << "Echo::tick(): channel and StkFrames arguments are incompatible!";
    00083     handleError( StkError::FUNCTION_ARGUMENT );
    00084   }
    00085 #endif
    00086
    00087   StkFloat *samples = &frames[channel];
    00088   unsigned int hop = frames.channels();
    00089   for ( unsigned int i=0; i<frames.frames(); i++, samples += hop ) {
    00090     *samples = effectMix_ * ( delayLine_.tick( *samples ) - *samples ) + *samples;
    00091   }
    00092
    00093   lastFrame_[0] = *(samples-hop);
    00094   return frames;
    00095 }

StkFrames & stk::Echo::tick | ( | StkFrames & | iFrames,
|  | StkFrames & | oFrames,
|  | unsigned int | iChannel = `0`,
|  | unsigned int | oChannel = `0` |
| ) |  |  | `[inline]`

Take a channel of the `iFrames` object as inputs to the effect and write outputs to the `oFrames` object.

The `iFrames` object reference is returned. Each channel argument must be less than the number of channels in the corresponding StkFrames argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an StkError exception.

    00098 {
    00099 #if defined(_STK_DEBUG_)
    00100   if ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
    00101     oStream_ << "Echo::tick(): channel and StkFrames arguments are incompatible!";
    00102     handleError( StkError::FUNCTION_ARGUMENT );
    00103   }
    00104 #endif
    00105
    00106   StkFloat *iSamples = &iFrames[iChannel];
    00107   StkFloat *oSamples = &oFrames[oChannel];
    00108   unsigned int iHop = iFrames.channels(), oHop = oFrames.channels();
    00109   for ( unsigned int i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) {
    00110     *oSamples = effectMix_ * ( delayLine_.tick( *iSamples ) - *iSamples ) + *iSamples;
    00111   }
    00112
    00113   lastFrame_[0] = *(oSamples-oHop);
    00114   return iFrames;
    00115 }

The documentation for this class was generated from the following file:

- Echo.h

The Synthesis ToolKit in C++ (STK)
©1995-2012 Perry R. Cook and Gary P. Scavone. All Rights Reserved.