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139 lines
4.3 KiB
139 lines
4.3 KiB
/*
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Copyright (C) 2000 Jeff Tranter
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tranter@pobox.com
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Stefan Westerfeld
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stefan@space.twc.de
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Jens Hahn
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Jens.Hahn@t-online.de
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2001 Matthias Kretz
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kretz@kde.org
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with this library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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*/
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#include "artsmodulessynth.h"
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#include "stdsynthmodule.h"
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#include <math.h>
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using namespace Arts;
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// This delays the input signal for an amount of time. The time
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// specification must be between 0 and 1 for a delay between 0 seconds
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// and 1 second.
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//
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// This kind of delay may not be used in feedback structures. This is
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// because it's a variable delay. You can modify it's length while it
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// is running, and even set it down to zero. But since in a feedback
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// structure the own output is needed to calculate the next samples, a
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// delay whose value could drop to zero during synthesis could lead to
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// a stall situation.
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//
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// Use CDELAYs in that setup, perhaps combine a small constant delay
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// (of 0.001 seconds) with a flexible delay.
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//
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// You can also combine a CDELAY and a DELAY to achieve a variable
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// length delay with a minimum value in a feedback loop. Just make
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// sure that you have a CDELAY involved.
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class Synth_DELAY_impl : virtual public Synth_DELAY_skel,
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virtual public StdSynthModule
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{
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protected:
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unsigned long _buffersize;
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unsigned long _bitmask;
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float * _buffer;
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float _maxdelay;
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unsigned int _writepos;
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public:
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Synth_DELAY_impl() : _buffersize( 0 ), _bitmask( 0 ), _buffer( 0 ), _maxdelay( 0 ), _writepos( 0 )
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{
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maxdelay( 1 ); // take a one second buffer if nothing else is specified
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}
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~Synth_DELAY_impl()
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{
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delete[] _buffer;
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}
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void streamInit()
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{
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// initialize buffer to all zeroes
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for ( unsigned long i = 0; i < _buffersize; i++ )
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_buffer[i] = 0.0;
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}
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void calculateBlock(unsigned long samples)
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{
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for( unsigned long i = 0; i <samples; i++ )
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{
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double int_pos;
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double error = modf( time[i] * samplingRateFloat, &int_pos );
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unsigned long readpos1 = ( _writepos - (unsigned long)(int_pos) ) & _bitmask;
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unsigned long readpos2 = ( readpos1 - 1 ) & _bitmask; // Shouldn't this be +1? (mkretz)
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// No, it's right this way:
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// ( 1 - error ) needs to be multiplied with the second
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// sample; error with the first
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_buffer[_writepos] = invalue[i];
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outvalue[i] = _buffer[readpos1] * ( 1 - error ) + _buffer[readpos2] * error;
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_writepos++;
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_writepos &= _bitmask;
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}
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}
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float maxdelay() { return _maxdelay; }
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void maxdelay(float newmaxdelay)
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{
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if( newmaxdelay <= 0 )
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return;
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_maxdelay = newmaxdelay;
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double n = ceil( log( double(_maxdelay * samplingRateFloat) ) / log( 2. ) );
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unsigned long newbuffersize = (unsigned long)( pow( 2, n ) );
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unsigned long newbitmask = newbuffersize - 1;
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if( newbuffersize != _buffersize )
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{
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float *newbuffer = new float[newbuffersize];
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if( newbuffersize > _buffersize ) {
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for( unsigned long i = 0; i < _buffersize; i++ ) {
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newbuffer[i] = _buffer[_writepos];
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_writepos++;
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_writepos &= newbitmask;
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}
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for( unsigned long i = _buffersize; i < newbuffersize; i++ )
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newbuffer[i] = 0;
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} else {
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_writepos -= newbuffersize;
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_writepos &= newbitmask;
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for( unsigned long i = 0; i < newbuffersize; i++ ) {
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newbuffer[i] = _buffer[_writepos];
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_writepos++;
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_writepos &= newbitmask;
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}
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}
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_buffer = newbuffer;
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_buffersize = newbuffersize;
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_bitmask = newbitmask;
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}
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maxdelay_changed( _maxdelay );
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}
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};
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REGISTER_IMPLEMENTATION(Synth_DELAY_impl);
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