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Diffstat (limited to 'src/loris/NoiseGenerator.C')
| -rw-r--r-- | src/loris/NoiseGenerator.C | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/loris/NoiseGenerator.C b/src/loris/NoiseGenerator.C new file mode 100644 index 0000000..c1c7c0e --- /dev/null +++ b/src/loris/NoiseGenerator.C @@ -0,0 +1,186 @@ +/* + * This is the Loris C++ Class Library, implementing analysis, + * manipulation, and synthesis of digitized sounds using the Reassigned + * Bandwidth-Enhanced Additive Sound Model. + * + * Loris is Copyright (c) 1999-2010 by Kelly Fitz and Lippold Haken + * + * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * + * NoiseGenerator.C + * + * Implementation of a class representing a gaussian noise generator, filtered and + * used as a modulator in bandwidth-enhanced synthesis. + * + * Kelly Fitz, 5 June 2003 + * revised 11 October 2009 + * loris@cerlsoundgroup.org + * + * http://www.cerlsoundgroup.org/Loris/ + * + */ + +#if HAVE_CONFIG_H + #include "config.h" +#endif + +#include "NoiseGenerator.h" +#include <cmath> +#include <numeric> + + +// begin namespace +namespace Loris { + +// --- construction --- + +// --------------------------------------------------------------------------- +// (default) constructor +// --------------------------------------------------------------------------- +//! Create a new noise generator with the (optionally) specified +//! seed (default is 1.0). +//! +//! \param initSeed is the initial seed for the random number generator +// +NoiseGenerator::NoiseGenerator( double initSeed ) : + m_useed( initSeed ), + m_gset( 0 ), + m_iset( false ) +{ +} + +// --------------------------------------------------------------------------- +// seed +// --------------------------------------------------------------------------- +//! Re-seed the random number generator. +//! +//! \param newSeed is the new seed for the random number generator +// +void +NoiseGenerator::seed( double newSeed ) +{ + m_useed = newSeed; +} + +// --- random number generation --- + +// --------------------------------------------------------------------------- +// uniform random number generator +// --------------------------------------------------------------------------- +// Taken from "Random Number Generators: Good Ones Are Hard To Find," +// Stephen Park and Keith Miller, Communications of the ACM, October 1988, +// vol. 31, Number 10. +// +// This version will work as long as floating point values are represented +// with at least a 46 bit mantissa. The IEEE standard 64 bit floating point +// format has a 53 bit mantissa. +// +// The correctness of the implementation can be checked by confirming that +// after 10000 iterations, the seed, initialized to 1, is 1043618065. +// I have confirmed this. +// +// I have also confirmed that it still works (is correct after 10000 +// iterations) when I replace the divides with multiplies by oneOverM. +// +// Returns a uniformly distributed random double on the range [0., 1.). +// +// -kel 7 Nov 1997. +// +// trunc() is a problem. It's not in cmath, officially, though +// Metrowerks has it in there. SGI has it in math.h which is +// (erroneously!) included in g++ cmath, but trunc is not imported +// into std. For these two compilers, could just import std. But +// trnc doesn't seem to exist anywhere in Linux g++, so use std::modf(). +// DON'T use integer conversion, because long int ins't as long +// as double's mantissa! +// +static inline double trunc( double x ) { double y; std::modf(x, &y); return y; } + +inline double +NoiseGenerator::uniform( void ) +{ + static const double a = 16807.L; + static const double m = 2147483647.L; // == LONG_MAX + static const double oneOverM = 1.L / m; + + double temp = a * m_useed; + m_useed = temp - m * trunc( temp * oneOverM ); + return m_useed * oneOverM; +} + +// --------------------------------------------------------------------------- +// gaussian_normal +// --------------------------------------------------------------------------- +// Approximate the normal distribution using the Box-Muller transformation. +// This is a better approximation and faster algorithm than the 12 u.v. sum. +// +// This is slightly different than the thing I got off the web, I (have to) +// assume (for now) that I knew what I was doing when I altered it. +// +inline double +NoiseGenerator::gaussian_normal( void ) +{ + //static int m_iset = 0; // boolean really, now member variables + //static double m_gset; + + double r = 1., fac, v1, v2; + + if ( ! m_iset ) + { + v1 = 2. * uniform() - 1.; + v2 = 2. * uniform() - 1.; + r = v1*v1 + v2*v2; + while( r >= 1. ) + { + // v1 = 2. * uniform() - 1.; + v1 = v2; + v2 = 2. * uniform() - 1.; + r = v1*v1 + v2*v2; + } + + fac = std::sqrt( -2. * std::log(r) / r ); + m_gset = v1 * fac; + m_iset = true; + return v2 * fac; + } + else + { + m_iset = false; + return m_gset; + } +} + +// --- sample generation --- + +// --------------------------------------------------------------------------- +// sample +// --------------------------------------------------------------------------- +//! Generate and return a new sample of Gaussian noise having zero +//! mean and unity standard deviation. Approximate the normal distribution +//! using the Box-Muller transformation applied to a uniform random number +//! generator taken from "Random Number Generators: Good Ones Are Hard To Find," +//! Stephen Park and Keith Miller, Communications of the ACM, October 1988, +//! vol. 31, Number 10. +// +double +NoiseGenerator::sample( void ) +{ + double sample = gaussian_normal(); + return sample; +} + + +} // end of namespace Loris |