mirror of
https://github.com/cookiengineer/audacity
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116 lines
3.4 KiB
C++
116 lines
3.4 KiB
C++
/***************************************************/
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/*! \class Delay
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\brief STK non-interpolating delay line class.
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This protected Filter subclass implements
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a non-interpolating digital delay-line.
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A fixed maximum length of 4095 and a delay
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of zero is set using the default constructor.
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Alternatively, the delay and maximum length
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can be set during instantiation with an
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overloaded constructor.
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A non-interpolating delay line is typically
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used in fixed delay-length applications, such
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as for reverberation.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
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*/
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/***************************************************/
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#ifndef STK_DELAY_H
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#define STK_DELAY_H
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#include "Filter.h"
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namespace Nyq
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{
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class Delay : protected Filter
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{
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public:
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//! Default constructor creates a delay-line with maximum length of 4095 samples and zero delay.
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Delay();
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//! Overloaded constructor which specifies the current and maximum delay-line lengths.
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/*!
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An StkError will be thrown if the delay parameter is less than
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zero, the maximum delay parameter is less than one, or the delay
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parameter is greater than the maxDelay value.
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*/
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Delay(unsigned long delay, unsigned long maxDelay);
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//! Class destructor.
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virtual ~Delay();
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//! Clears the internal state of the delay line.
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void clear();
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//! Set the maximum delay-line length.
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/*!
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This method should generally only be used during initial setup
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of the delay line. If it is used between calls to the tick()
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function, without a call to clear(), a signal discontinuity will
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likely occur. If the current maximum length is greater than the
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new length, no change will be made.
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*/
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void setMaximumDelay(unsigned long delay);
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//! Set the delay-line length.
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/*!
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The valid range for \e theDelay is from 0 to the maximum delay-line length.
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*/
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void setDelay(unsigned long delay);
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//! Return the current delay-line length.
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unsigned long getDelay(void) const;
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//! Calculate and return the signal energy in the delay-line.
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StkFloat energy(void) const;
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//! Return the value at \e tapDelay samples from the delay-line input.
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/*!
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The tap point is determined modulo the delay-line length and is
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relative to the last input value (i.e., a tapDelay of zero returns
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the last input value).
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*/
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StkFloat contentsAt(unsigned long tapDelay);
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//! Return the last computed output value.
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StkFloat lastOut(void) const;
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//! Return the value which will be output by the next call to tick().
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/*!
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This method is valid only for delay settings greater than zero!
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*/
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virtual StkFloat nextOut(void);
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//! Input one sample to the filter and return one output.
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virtual StkFloat tick(StkFloat sample);
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//! Take a channel of the StkFrames object as inputs to the filter and replace with corresponding outputs.
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/*!
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The \c channel argument should be zero or greater (the first
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channel is specified by 0). An StkError will be thrown if the \c
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channel argument is equal to or greater than the number of
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channels in the StkFrames object.
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*/
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virtual StkFrames& tick( StkFrames& frames, unsigned int channel = 0 );
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protected:
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// This function must be implemented in all subclasses. It is used
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// to get around a C++ problem with overloaded virtual functions.
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virtual StkFloat computeSample( StkFloat input );
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unsigned long inPoint_;
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unsigned long outPoint_;
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StkFloat delay_;
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};
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} // namespace Nyq
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#endif
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