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/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
** of its contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "spectrum.h"
#include "utils.h"
#include <QByteArray>
#include <QtMultimedia/QAudioFormat>
#include <QtCore/qmath.h>
#include <QtCore/qendian.h>
void generateTone(const SweptTone &tone, const QAudioFormat &format, QByteArray &buffer)
{
Q_ASSERT(isPCMS16LE(format));
const int channelBytes = format.sampleSize() / 8;
const int sampleBytes = format.channels() * channelBytes;
int length = buffer.size();
const int numSamples = buffer.size() / sampleBytes;
Q_ASSERT(length % sampleBytes == 0);
Q_UNUSED(sampleBytes) // suppress warning in release builds
unsigned char *ptr = reinterpret_cast<unsigned char *>(buffer.data());
qreal phase = 0.0;
const qreal d = 2 * M_PI / format.frequency();
// We can't generate a zero-frequency sine wave
const qreal startFreq = tone.startFreq ? tone.startFreq : 1.0;
// Amount by which phase increases on each sample
qreal phaseStep = d * startFreq;
// Amount by which phaseStep increases on each sample
// If this is non-zero, the output is a frequency-swept tone
const qreal phaseStepStep = d * (tone.endFreq - startFreq) / numSamples;
while (length) {
const qreal x = tone.amplitude * qSin(phase);
const qint16 value = realToPcm(x);
for (int i=0; i<format.channels(); ++i) {
qToLittleEndian<qint16>(value, ptr);
ptr += channelBytes;
length -= channelBytes;
}
phase += phaseStep;
while (phase > 2 * M_PI)
phase -= 2 * M_PI;
phaseStep += phaseStepStep;
}
}
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