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50
51#include "spectrumanalyser.h"
52#include "utils.h"
53#include "fftreal_wrapper.h"
54
55#include <qmath.h>
56#include <qmetatype.h>
57#include <QAudioFormat>
58#include <QThread>
59
60SpectrumAnalyserThread::SpectrumAnalyserThread(QObject *parent)
61 : QObject(parent)
62#ifndef DISABLE_FFT
63 , m_fft(new FFTRealWrapper)
64#endif
65 , m_numSamples(SpectrumLengthSamples)
66 , m_windowFunction(DefaultWindowFunction)
67 , m_window(SpectrumLengthSamples, 0.0)
68 , m_input(SpectrumLengthSamples, 0.0)
69 , m_output(SpectrumLengthSamples, 0.0)
70 , m_spectrum(SpectrumLengthSamples)
71#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD
72 , m_thread(new QThread(this))
73#endif
74{
75#ifdef SPECTRUM_ANALYSER_SEPARATE_THREAD
76 // moveToThread() cannot be called on a QObject with a parent
77 setParent(0);
78 moveToThread(thread: m_thread);
79 m_thread->start();
80#endif
81 calculateWindow();
82}
83
84SpectrumAnalyserThread::~SpectrumAnalyserThread()
85{
86#ifndef DISABLE_FFT
87 delete m_fft;
88#endif
89}
90
91void SpectrumAnalyserThread::setWindowFunction(WindowFunction type)
92{
93 m_windowFunction = type;
94 calculateWindow();
95}
96
97void SpectrumAnalyserThread::calculateWindow()
98{
99 for (int i=0; i<m_numSamples; ++i) {
100 DataType x = 0.0;
101
102 switch (m_windowFunction) {
103 case NoWindow:
104 x = 1.0;
105 break;
106 case HannWindow:
107 x = 0.5 * (1 - qCos(v: (2 * M_PI * i) / (m_numSamples - 1)));
108 break;
109 default:
110 Q_ASSERT(false);
111 }
112
113 m_window[i] = x;
114 }
115}
116
117void SpectrumAnalyserThread::calculateSpectrum(const QByteArray &buffer,
118 int inputFrequency,
119 int bytesPerSample)
120{
121#ifndef DISABLE_FFT
122 Q_ASSERT(buffer.size() == m_numSamples * bytesPerSample);
123
124 // Initialize data array
125 const char *ptr = buffer.constData();
126 for (int i=0; i<m_numSamples; ++i) {
127 const qint16 pcmSample = *reinterpret_cast<const qint16*>(ptr);
128 // Scale down to range [-1.0, 1.0]
129 const DataType realSample = pcmToReal(pcm: pcmSample);
130 const DataType windowedSample = realSample * m_window[i];
131 m_input[i] = windowedSample;
132 ptr += bytesPerSample;
133 }
134
135 // Calculate the FFT
136 m_fft->calculateFFT(in: m_output.data(), out: m_input.data());
137
138 // Analyze output to obtain amplitude and phase for each frequency
139 for (int i=2; i<=m_numSamples/2; ++i) {
140 // Calculate frequency of this complex sample
141 m_spectrum[i].frequency = qreal(i * inputFrequency) / (m_numSamples);
142
143 const qreal real = m_output[i];
144 qreal imag = 0.0;
145 if (i>0 && i<m_numSamples/2)
146 imag = m_output[m_numSamples/2 + i];
147
148 const qreal magnitude = qSqrt(v: real*real + imag*imag);
149 qreal amplitude = SpectrumAnalyserMultiplier * qLn(v: magnitude);
150
151 // Bound amplitude to [0.0, 1.0]
152 m_spectrum[i].clipped = (amplitude > 1.0);
153 amplitude = qMax(a: qreal(0.0), b: amplitude);
154 amplitude = qMin(a: qreal(1.0), b: amplitude);
155 m_spectrum[i].amplitude = amplitude;
156 }
157#endif
158
159 emit calculationComplete(spectrum: m_spectrum);
160}
161
162
163//=============================================================================
164// SpectrumAnalyser
165//=============================================================================
166
167SpectrumAnalyser::SpectrumAnalyser(QObject *parent)
168 : QObject(parent)
169 , m_thread(new SpectrumAnalyserThread(this))
170 , m_state(Idle)
171#ifdef DUMP_SPECTRUMANALYSER
172 , m_count(0)
173#endif
174{
175 connect(sender: m_thread, signal: &SpectrumAnalyserThread::calculationComplete,
176 receiver: this, slot: &SpectrumAnalyser::calculationComplete);
177}
178
179SpectrumAnalyser::~SpectrumAnalyser()
180{
181
182}
183
184#ifdef DUMP_SPECTRUMANALYSER
185void SpectrumAnalyser::setOutputPath(const QString &outputDir)
186{
187 m_outputDir.setPath(outputDir);
188 m_textFile.setFileName(m_outputDir.filePath("spectrum.txt"));
189 m_textFile.open(QIODevice::WriteOnly | QIODevice::Text);
190 m_textStream.setDevice(&m_textFile);
191}
192#endif
193
194//-----------------------------------------------------------------------------
195// Public functions
196//-----------------------------------------------------------------------------
197
198void SpectrumAnalyser::setWindowFunction(WindowFunction type)
199{
200 const bool b = QMetaObject::invokeMethod(obj: m_thread, member: "setWindowFunction",
201 type: Qt::AutoConnection,
202 Q_ARG(WindowFunction, type));
203 Q_ASSERT(b);
204 Q_UNUSED(b) // suppress warnings in release builds
205}
206
207void SpectrumAnalyser::calculate(const QByteArray &buffer,
208 const QAudioFormat &format)
209{
210 // QThread::currentThread is marked 'for internal use only', but
211 // we're only using it for debug output here, so it's probably OK :)
212 SPECTRUMANALYSER_DEBUG << "SpectrumAnalyser::calculate"
213 << QThread::currentThread()
214 << "state" << m_state;
215
216 if (isReady()) {
217 Q_ASSERT(isPCMS16LE(format));
218
219 const int bytesPerSample = format.sampleSize() * format.channelCount() / 8;
220
221#ifdef DUMP_SPECTRUMANALYSER
222 m_count++;
223 const QString pcmFileName = m_outputDir.filePath(QString("spectrum_%1.pcm").arg(m_count, 4, 10, QChar('0')));
224 QFile pcmFile(pcmFileName);
225 pcmFile.open(QIODevice::WriteOnly);
226 const int bufferLength = m_numSamples * bytesPerSample;
227 pcmFile.write(buffer, bufferLength);
228
229 m_textStream << "TimeDomain " << m_count << "\n";
230 const qint16* input = reinterpret_cast<const qint16*>(buffer);
231 for (int i=0; i<m_numSamples; ++i) {
232 m_textStream << i << "\t" << *input << "\n";
233 input += format.channels();
234 }
235#endif
236
237 m_state = Busy;
238
239 // Invoke SpectrumAnalyserThread::calculateSpectrum using QMetaObject. If
240 // m_thread is in a different thread from the current thread, the
241 // calculation will be done in the child thread.
242 // Once the calculation is finished, a calculationChanged signal will be
243 // emitted by m_thread.
244 const bool b = QMetaObject::invokeMethod(obj: m_thread, member: "calculateSpectrum",
245 type: Qt::AutoConnection,
246 Q_ARG(QByteArray, buffer),
247 Q_ARG(int, format.sampleRate()),
248 Q_ARG(int, bytesPerSample));
249 Q_ASSERT(b);
250 Q_UNUSED(b) // suppress warnings in release builds
251
252#ifdef DUMP_SPECTRUMANALYSER
253 m_textStream << "FrequencySpectrum " << m_count << "\n";
254 FrequencySpectrum::const_iterator x = m_spectrum.begin();
255 for (int i=0; i<m_numSamples; ++i, ++x)
256 m_textStream << i << "\t"
257 << x->frequency << "\t"
258 << x->amplitude<< "\t"
259 << x->phase << "\n";
260#endif
261 }
262}
263
264bool SpectrumAnalyser::isReady() const
265{
266 return (Idle == m_state);
267}
268
269void SpectrumAnalyser::cancelCalculation()
270{
271 if (Busy == m_state)
272 m_state = Cancelled;
273}
274
275
276//-----------------------------------------------------------------------------
277// Private slots
278//-----------------------------------------------------------------------------
279
280void SpectrumAnalyser::calculationComplete(const FrequencySpectrum &spectrum)
281{
282 Q_ASSERT(Idle != m_state);
283 if (Busy == m_state)
284 emit spectrumChanged(spectrum);
285 m_state = Idle;
286}
287

source code of qtmultimedia/examples/multimedia/spectrum/app/spectrumanalyser.cpp