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Diffstat (limited to 'demos/spectrum/app/tonegenerator.cpp')
-rw-r--r-- | demos/spectrum/app/tonegenerator.cpp | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/demos/spectrum/app/tonegenerator.cpp b/demos/spectrum/app/tonegenerator.cpp new file mode 100644 index 0000000..6458a7d --- /dev/null +++ b/demos/spectrum/app/tonegenerator.cpp @@ -0,0 +1,92 @@ +/**************************************************************************** +** +** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the examples of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#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; + } +} + |