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Diffstat (limited to 'examples/multimedia/spectrum/app/tonegenerator.cpp')
-rw-r--r-- | examples/multimedia/spectrum/app/tonegenerator.cpp | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/examples/multimedia/spectrum/app/tonegenerator.cpp b/examples/multimedia/spectrum/app/tonegenerator.cpp new file mode 100644 index 000000000..51a1de357 --- /dev/null +++ b/examples/multimedia/spectrum/app/tonegenerator.cpp @@ -0,0 +1,90 @@ +/**************************************************************************** +** +** Copyright (C) 2012 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 <QAudioFormat> +#include <qmath.h> +#include <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.channelCount() * 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.sampleRate(); + + // 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.channelCount(); ++i) { + qToLittleEndian<qint16>(value, ptr); + ptr += channelBytes; + length -= channelBytes; + } + + phase += phaseStep; + while (phase > 2 * M_PI) + phase -= 2 * M_PI; + phaseStep += phaseStepStep; + } +} |