/usr/include/svxlink/AsyncAudioNoiseAdder.h is in libasyncaudio-dev 17.12.1-2.
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@file AsyncAudioNoiseAdder.h
@brief A class to add white gaussian noise to an audio stream
@author Tobias Blomberg / SM0SVX
@date 2015-03-08
\verbatim
Async - A library for programming event driven applications
Copyright (C) 2003-2015 Tobias Blomberg / SM0SVX
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
\endverbatim
*/
#ifndef ASYNC_AUDIO_NOISE_ADDER
#define ASYNC_AUDIO_NOISE_ADDER
/****************************************************************************
*
* System Includes
*
****************************************************************************/
#include <string>
/****************************************************************************
*
* Project Includes
*
****************************************************************************/
/****************************************************************************
*
* Local Includes
*
****************************************************************************/
#include <AsyncAudioProcessor.h>
/****************************************************************************
*
* Forward declarations
*
****************************************************************************/
/****************************************************************************
*
* Namespace
*
****************************************************************************/
namespace Async
{
/****************************************************************************
*
* Forward declarations of classes inside of the declared namespace
*
****************************************************************************/
/****************************************************************************
*
* Defines & typedefs
*
****************************************************************************/
/****************************************************************************
*
* Exported Global Variables
*
****************************************************************************/
/****************************************************************************
*
* Class definitions
*
****************************************************************************/
/**
@brief A class to add gaussian white noise to an audio stream
@author Tobias Blomberg / SM0SVX
@date 2015-03-08
This class implement a noise generator that add white gaussian noise to an
audio stream. The noise is generated using the Box-Muller transform which for
example is described on Wikipedia:
http://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
The class is not implemented as a pure audio source but rather as an audio pipe
component that should be inserted in the audio path.
*/
class AudioNoiseAdder : public AudioProcessor
{
public:
/**
* @brief Constuctor
* @param level_db The noise level in dB
*
* The level_db parameter deserve some clarification. A level of 0dB give
* the same power as in a full scale sine wave. This make it possible to
* add noise to a generated signal under controlled conditions.
* For example, if a sine wave is generated in SvxLink with a level of 0dB
* and noise is added with a level of -10dB, we get a signal to noise ratio
* (SNR) of 10dB.
*/
AudioNoiseAdder(float level_db);
/**
* @brief Destructor
*/
~AudioNoiseAdder(void);
protected:
/**
* @brief Process incoming samples and put them into the output buffer
* @param dest Destination buffer
* @param src Source buffer
* @param count Number of samples in the source buffer
*
* This function is called from the base class to do the actual
* processing of the incoming samples. All samples must
* be processed, otherwise they are lost and the output buffer will
* contain garbage.
*/
void processSamples(float *dest, const float *src, int count);
private:
float sigma; // Standard deviation of the generated noise
float z1;
bool generate;
unsigned int seed;
AudioNoiseAdder(const AudioNoiseAdder&);
AudioNoiseAdder& operator=(const AudioNoiseAdder&);
float generateGaussianNoise(void);
}; /* class AudioNoiseAdder */
} /* namespace */
#endif /* ASYNC_AUDIO_NOISE_ADDER */
/*
* This file has not been truncated
*/
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