/usr/include/svxlink/AsyncAudioGenerator.h is in libasyncaudio-dev 17.12.1-2.
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@file AsyncAudioGenerator.h
@brief An audio generator
@author Tobias Blomberg / SM0SVX
@date 2015-09-28
\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_GENERATOR_INCLUDED
#define ASYNC_AUDIO_GENERATOR_INCLUDED
/****************************************************************************
*
* System Includes
*
****************************************************************************/
#include <cmath>
/****************************************************************************
*
* Project Includes
*
****************************************************************************/
#include <AsyncAudioSource.h>
/****************************************************************************
*
* Local Includes
*
****************************************************************************/
/****************************************************************************
*
* Forward declarations
*
****************************************************************************/
/****************************************************************************
*
* Namespace
*
****************************************************************************/
namespace Async
{
/****************************************************************************
*
* Forward declarations of classes inside of the declared namespace
*
****************************************************************************/
/****************************************************************************
*
* Defines & typedefs
*
****************************************************************************/
/****************************************************************************
*
* Exported Global Variables
*
****************************************************************************/
/****************************************************************************
*
* Class definitions
*
****************************************************************************/
/**
@brief A class for generating periodic audio signals
@author Tobias Blomberg / SM0SVX
@date 2015-09-28
This class is used to generate periodic audio signals. Note that audio samples
will be produced in an endless loop until the connected sink stop the flow.
This means that a sink have to be connected before enabling the generator or
the application will get stuck. There also must be some form of flow control
downstream in the audio pipe. One way to get flow control, if there are none
naturally, is to use an Async::AudioPacer.
*/
class AudioGenerator : public Async::AudioSource
{
public:
/**
* @brief The type of waveform to generate
*/
typedef enum {
SIN, ///< Sine wave
SQUARE ///< Square wave
} Waveform;
/**
* @brief Contructor
* @param wf The waveform to use (@see Waveform)
*/
explicit AudioGenerator(Waveform wf=SIN)
: pos(0), fq(0.0), level(0.0), sample_rate(INTERNAL_SAMPLE_RATE),
waveform(wf), power(0.0)
{
}
/**
* @brief Destructor
*/
~AudioGenerator(void)
{
enable(false);
}
/**
* @brief Set which waveform to use
* @param wf The waveform to use (@see Waveform)
*/
void setWaveform(Waveform wf)
{
waveform = wf;
calcLevel();
}
/**
* @brief Set the audio frequency
* @param tone_fq The frequency in Hz
*/
void setFq(double tone_fq)
{
fq = tone_fq;
}
/**
* @brief Set the power of the generated signal
* @param pwr_db The power of the signal in dB
*
* Use this function to set the power of the generated signal. 0dB power is
* defined as a full-scale sine wave.
*/
void setPower(float pwr_db)
{
power = pow(10.0, pwr_db / 10.0f) / 2;
calcLevel();
}
/**
* @brief Enable or disable the generator
* @param enable Set to \em true to enable the generator or \em false
* to disable it
*/
void enable(bool enable)
{
if (enable && (fq != 0))
{
pos = 0;
writeSamples();
}
}
/**
* @brief Resume audio output to the sink
*
* This function is normally only called from a connected sink object.
*/
void resumeOutput(void)
{
writeSamples();
}
/**
* @brief The registered sink has flushed all samples
*
* This function is normally only called from a connected sink object.
*/
void allSamplesFlushed(void)
{
}
private:
static const int BLOCK_SIZE = 128;
unsigned pos;
double fq;
double level;
int sample_rate;
Waveform waveform;
float power;
AudioGenerator(const AudioGenerator&);
AudioGenerator& operator=(const AudioGenerator&);
/**
* @brief Calculate the peak level corresponding to the set power for
* the set waveform
*/
void calcLevel(void)
{
switch (waveform)
{
case SIN:
level = sqrt(2 * power);
break;
case SQUARE:
level = sqrt(power);
break;
default:
level = 1.0;
break;
}
}
/**
* @brief Write samples to the connected sink
*/
void writeSamples(void)
{
int written;
do {
float buf[BLOCK_SIZE];
for (int i=0; i<BLOCK_SIZE; ++i)
{
switch (waveform)
{
case SIN:
buf[i] = level * sin(2 * M_PI * fq * (pos+i) / sample_rate);
break;
case SQUARE:
buf[i] = level * (sin(2 * M_PI * fq * (pos+i) / sample_rate)
> 0.0 ? 1 : -1);
break;
default:
buf[i] = 0;
break;
}
}
written = sinkWriteSamples(buf, BLOCK_SIZE);
pos += written;
} while (written != 0);
}
}; /* class AudioGenerator */
} /* namespace */
#endif /* ASYNC_AUDIO_GENERATOR_INCLUDED */
/*
* This file has not been truncated
*/
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