diff options
Diffstat (limited to 'arts/modules/synth/synth_pitch_shift_impl.cpp')
| -rw-r--r-- | arts/modules/synth/synth_pitch_shift_impl.cpp | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/arts/modules/synth/synth_pitch_shift_impl.cpp b/arts/modules/synth/synth_pitch_shift_impl.cpp new file mode 100644 index 00000000..37217c8a --- /dev/null +++ b/arts/modules/synth/synth_pitch_shift_impl.cpp @@ -0,0 +1,196 @@ +/* + + Copyright (C) 2000 Jeff Tranter + tranter@pobox.com + + (C) 1999 Stefan Westerfeld + stefan@space.twc.de + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + + */ + +#include <math.h> +#include "artsmodulessynth.h" +#include "stdsynthmodule.h" + +using namespace Arts; + +class Synth_PITCH_SHIFT_impl : virtual public Synth_PITCH_SHIFT_skel, + virtual public StdSynthModule +{ +protected: + float _speed, _frequency; + + enum { MAXDELAY = 44100 }; + float *dbuffer; + float lfopos, b1pos, b2pos, b1inc, b2inc; + bool b1reset, b2reset, initialized; + int dbpos; + +public: + Synth_PITCH_SHIFT_impl() : _speed(1.0), _frequency(5.0) + { + } + + float speed() { return _speed; } + void speed(float newSpeed) { _speed = newSpeed; } + + float frequency() { return _frequency; } + void frequency(float newFrequency) { _frequency = newFrequency; } + + + void streamInit() + { + dbuffer = new float[MAXDELAY]; + for (dbpos=0; dbpos<MAXDELAY; dbpos++) + dbuffer[dbpos] = 0; + + dbpos = 0; + initialized = false; + lfopos = 0; + } + void streamEnd() + { + delete[] dbuffer; + } + + void calculateBlock(unsigned long samples) + { + float *outend = outvalue + samples; + float fsr = (float)samplingRate; + float pi2 = 2*M_PI; + float lfo, b1value, b2value; + float lfoposinc = _frequency / fsr; + + if (!initialized) + { + if (_speed <= 1.0) { + b1pos = b2pos = 0.0; + b1inc = b2inc = 1.0 - _speed; + } else { + /* not yet sure what would be a nice initialization here? */ + b1pos = b2pos = 0.0; + b1inc = b2inc = 0.0; + } + initialized = true; + } + + while (outvalue < outend) + { + /* + * fill delay buffer with the input signal + */ + dbuffer[dbpos] = *invalue++; + + lfopos += lfoposinc; + lfopos -= floor(lfopos); + + if (lfopos < 0.25) { + b1reset = b2reset = false; + } + + /* + * _speed < 1.0 (downpitching) + * + * start with current sample and increase delay slowly + * + * _speed > 1.0 (uppitching) + * + * start with a sample from long ago and slowly decrease delay + */ + if (!b1reset && lfopos > 0.25) { + if (_speed <= 1.0) { + b1pos = 0; + b1inc = 1 - _speed; + } else { + b1inc = 1 - _speed; + b1pos = 10 + ((-b1inc) * (1 / lfoposinc)); + /* 10+ are not strictly necessary */ + } + b1reset = true; + } + + if (!b2reset && lfopos > 0.75) { + if (_speed <= 1.0) { + b2pos = 0; + b2inc = 1 - _speed; + } else{ + b2inc = 1 - _speed; + b2pos = 10 + ((-b2inc) * (1/lfoposinc)); + /* 10+ are not strictly necessary */ + } + b2reset = true; + } + + b1pos += b1inc; + b2pos += b2inc; + + int position, position1; + double error,int_pos; + + /* + * Interpolate value from buffer position 1 + */ + error = modf(b1pos, &int_pos); + + position = dbpos - (int)int_pos; + if (position < 0) + position += MAXDELAY; + position1 = position - 1; + if (position1 < 0) + position1 += MAXDELAY; + + b1value = dbuffer[position] * (1 - error) + dbuffer[position1] * error; + + /* + * Interpolate value from buffer position 2 + */ + error = modf(b2pos,&int_pos); + + position = dbpos - (int)int_pos; + if (position < 0) + position += MAXDELAY; + position1 = position-1; + if ( position1 < 0) + position1 += MAXDELAY; + + b2value = dbuffer[position]*(1-error) + dbuffer[position1]*error; + + /* + * Calculate output signal from these two buffers + */ + + lfo = (sin(pi2 * lfopos) + 1) / 2; + + /* position sin lfo variable + *------------------------------------------------------------------ + * lfo value: 0.25 1 1 => buffer 2 is used + * 0.75 -1 0 => buffer 1 is used + */ + + *outvalue++ = b1value * (1.0 - lfo) + b2value * lfo; + + /* + * increment delay buffer position + */ + dbpos++; + if (dbpos == MAXDELAY) + dbpos = 0; + } + } +}; + +REGISTER_IMPLEMENTATION(Synth_PITCH_SHIFT_impl); |