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1 /**************************************************************************** |
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2 ** |
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3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
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4 ** All rights reserved. |
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5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
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6 ** |
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7 ** This file is part of the examples of the Qt Toolkit. |
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8 ** |
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9 ** $QT_BEGIN_LICENSE:LGPL$ |
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10 ** No Commercial Usage |
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11 ** This file contains pre-release code and may not be distributed. |
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12 ** You may use this file in accordance with the terms and conditions |
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13 ** contained in the Technology Preview License Agreement accompanying |
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14 ** this package. |
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15 ** |
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16 ** GNU Lesser General Public License Usage |
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17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
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18 ** General Public License version 2.1 as published by the Free Software |
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19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
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20 ** packaging of this file. Please review the following information to |
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21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
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22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
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23 ** |
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24 ** In addition, as a special exception, Nokia gives you certain additional |
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25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
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26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
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27 ** |
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28 ** If you have questions regarding the use of this file, please contact |
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29 ** Nokia at qt-info@nokia.com. |
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30 ** |
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31 ** |
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32 ** |
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33 ** |
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34 ** |
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35 ** |
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36 ** |
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37 ** |
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38 ** $QT_END_LICENSE$ |
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39 ** |
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40 ****************************************************************************/ |
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41 |
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42 #include "spectrum.h" |
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43 #include "utils.h" |
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44 #include <QByteArray> |
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45 #include <QtMultimedia/QAudioFormat> |
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46 #include <QtCore/qmath.h> |
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47 #include <QtCore/qendian.h> |
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48 |
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49 void generateTone(const SweptTone &tone, const QAudioFormat &format, QByteArray &buffer) |
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50 { |
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51 Q_ASSERT(isPCMS16LE(format)); |
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52 |
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53 const int channelBytes = format.sampleSize() / 8; |
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54 const int sampleBytes = format.channels() * channelBytes; |
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55 int length = buffer.size(); |
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56 const int numSamples = buffer.size() / sampleBytes; |
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57 |
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58 Q_ASSERT(length % sampleBytes == 0); |
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59 Q_UNUSED(sampleBytes) // suppress warning in release builds |
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60 |
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61 unsigned char *ptr = reinterpret_cast<unsigned char *>(buffer.data()); |
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62 |
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63 qreal phase = 0.0; |
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64 |
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65 const qreal d = 2 * M_PI / format.frequency(); |
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66 |
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67 // We can't generate a zero-frequency sine wave |
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68 const qreal startFreq = tone.startFreq ? tone.startFreq : 1.0; |
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69 |
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70 // Amount by which phase increases on each sample |
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71 qreal phaseStep = d * startFreq; |
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72 |
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73 // Amount by which phaseStep increases on each sample |
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74 // If this is non-zero, the output is a frequency-swept tone |
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75 const qreal phaseStepStep = d * (tone.endFreq - startFreq) / numSamples; |
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76 |
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77 while (length) { |
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78 const qreal x = tone.amplitude * qSin(phase); |
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79 const qint16 value = realToPcm(x); |
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80 for (int i=0; i<format.channels(); ++i) { |
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81 qToLittleEndian<qint16>(value, ptr); |
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82 ptr += channelBytes; |
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83 length -= channelBytes; |
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84 } |
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85 |
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86 phase += phaseStep; |
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87 while (phase > 2 * M_PI) |
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88 phase -= 2 * M_PI; |
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89 phaseStep += phaseStepStep; |
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90 } |
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91 } |
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92 |