histogramwidget.cpp Example File

multimediawidgets/player/histogramwidget.cpp
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#include "histogramwidget.h" #include <QPainter> #include <QHBoxLayout> template <class T> static QVector<qreal> getBufferLevels(const T *buffer, int frames, int channels); class QAudioLevel : public QWidget { Q_OBJECT public: explicit QAudioLevel(QWidget *parent = 0); // Using [0; 1.0] range void setLevel(qreal level); protected: void paintEvent(QPaintEvent *event); private: qreal m_level; }; QAudioLevel::QAudioLevel(QWidget *parent) : QWidget(parent) , m_level(0.0) { setMinimumHeight(15); setMaximumHeight(50); } void QAudioLevel::setLevel(qreal level) { if (m_level != level) { m_level = level; update(); } } void QAudioLevel::paintEvent(QPaintEvent *event) { Q_UNUSED(event); QPainter painter(this); // draw level qreal widthLevel = m_level * width(); painter.fillRect(0, 0, widthLevel, height(), Qt::red); // clear the rest of the control painter.fillRect(widthLevel, 0, width(), height(), Qt::black); } HistogramWidget::HistogramWidget(QWidget *parent) : QWidget(parent) , m_levels(128) , m_isBusy(false) { m_processor.moveToThread(&m_processorThread); qRegisterMetaType<QVector<qreal> >("QVector<qreal>"); connect(&m_processor, SIGNAL(histogramReady(QVector<qreal>)), SLOT(setHistogram(QVector<qreal>))); m_processorThread.start(QThread::LowestPriority); setLayout(new QHBoxLayout); } HistogramWidget::~HistogramWidget() { m_processorThread.quit(); m_processorThread.wait(10000); } void HistogramWidget::processFrame(QVideoFrame frame) { if (m_isBusy && frame.isValid()) return; //drop frame m_isBusy = true; QMetaObject::invokeMethod(&m_processor, "processFrame", Qt::QueuedConnection, Q_ARG(QVideoFrame, frame), Q_ARG(int, m_levels)); } // This function returns the maximum possible sample value for a given audio format qreal getPeakValue(const QAudioFormat& format) { // Note: Only the most common sample formats are supported if (!format.isValid()) return qreal(0); if (format.codec() != "audio/pcm") return qreal(0); switch (format.sampleType()) { case QAudioFormat::Unknown: break; case QAudioFormat::Float: if (format.sampleSize() != 32) // other sample formats are not supported return qreal(0); return qreal(1.00003); case QAudioFormat::SignedInt: if (format.sampleSize() == 32) return qreal(INT_MAX); if (format.sampleSize() == 16) return qreal(SHRT_MAX); if (format.sampleSize() == 8) return qreal(CHAR_MAX); break; case QAudioFormat::UnSignedInt: if (format.sampleSize() == 32) return qreal(UINT_MAX); if (format.sampleSize() == 16) return qreal(USHRT_MAX); if (format.sampleSize() == 8) return qreal(UCHAR_MAX); break; } return qreal(0); } // returns the audio level for each channel QVector<qreal> getBufferLevels(const QAudioBuffer& buffer) { QVector<qreal> values; if (!buffer.isValid()) return values; if (!buffer.format().isValid() || buffer.format().byteOrder() != QAudioFormat::LittleEndian) return values; if (buffer.format().codec() != "audio/pcm") return values; int channelCount = buffer.format().channelCount(); values.fill(0, channelCount); qreal peak_value = getPeakValue(buffer.format()); if (qFuzzyCompare(peak_value, qreal(0))) return values; switch (buffer.format().sampleType()) { case QAudioFormat::Unknown: case QAudioFormat::UnSignedInt: if (buffer.format().sampleSize() == 32) values = getBufferLevels(buffer.constData<quint32>(), buffer.frameCount(), channelCount); if (buffer.format().sampleSize() == 16) values = getBufferLevels(buffer.constData<quint16>(), buffer.frameCount(), channelCount); if (buffer.format().sampleSize() == 8) values = getBufferLevels(buffer.constData<quint8>(), buffer.frameCount(), channelCount); for (int i = 0; i < values.size(); ++i) values[i] = qAbs(values.at(i) - peak_value / 2) / (peak_value / 2); break; case QAudioFormat::Float: if (buffer.format().sampleSize() == 32) { values = getBufferLevels(buffer.constData<float>(), buffer.frameCount(), channelCount); for (int i = 0; i < values.size(); ++i) values[i] /= peak_value; } break; case QAudioFormat::SignedInt: if (buffer.format().sampleSize() == 32) values = getBufferLevels(buffer.constData<qint32>(), buffer.frameCount(), channelCount); if (buffer.format().sampleSize() == 16) values = getBufferLevels(buffer.constData<qint16>(), buffer.frameCount(), channelCount); if (buffer.format().sampleSize() == 8) values = getBufferLevels(buffer.constData<qint8>(), buffer.frameCount(), channelCount); for (int i = 0; i < values.size(); ++i) values[i] /= peak_value; break; } return values; } template <class T> QVector<qreal> getBufferLevels(const T *buffer, int frames, int channels) { QVector<qreal> max_values; max_values.fill(0, channels); for (int i = 0; i < frames; ++i) { for (int j = 0; j < channels; ++j) { qreal value = qAbs(qreal(buffer[i * channels + j])); if (value > max_values.at(j)) max_values.replace(j, value); } } return max_values; } void HistogramWidget::processBuffer(QAudioBuffer buffer) { if (audioLevels.count() != buffer.format().channelCount()) { qDeleteAll(audioLevels); audioLevels.clear(); for (int i = 0; i < buffer.format().channelCount(); ++i) { QAudioLevel *level = new QAudioLevel(this); audioLevels.append(level); layout()->addWidget(level); } } QVector<qreal> levels = getBufferLevels(buffer); for (int i = 0; i < levels.count(); ++i) audioLevels.at(i)->setLevel(levels.at(i)); } void HistogramWidget::setHistogram(QVector<qreal> histogram) { m_isBusy = false; m_histogram = histogram; update(); } void HistogramWidget::paintEvent(QPaintEvent *event) { Q_UNUSED(event); if (!audioLevels.isEmpty()) return; QPainter painter(this); if (m_histogram.isEmpty()) { painter.fillRect(0, 0, width(), height(), QColor::fromRgb(0, 0, 0)); return; } qreal barWidth = width() / (qreal)m_histogram.size(); for (int i = 0; i < m_histogram.size(); i++) { qreal h = m_histogram[i] * height(); // draw level painter.fillRect(barWidth * i, height() - h, barWidth * (i + 1), height(), Qt::red); // clear the rest of the control painter.fillRect(barWidth * i, 0, barWidth * (i + 1), height() - h, Qt::black); } } void FrameProcessor::processFrame(QVideoFrame frame, int levels) { QVector<qreal> histogram(levels); do { if (!levels) break; if (!frame.map(QAbstractVideoBuffer::ReadOnly)) break; if (frame.pixelFormat() == QVideoFrame::Format_YUV420P || frame.pixelFormat() == QVideoFrame::Format_NV12) { // Process YUV data uchar *b = frame.bits(); for (int y = 0; y < frame.height(); y++) { uchar *lastPixel = b + frame.width(); for (uchar *curPixel = b; curPixel < lastPixel; curPixel++) histogram[(*curPixel * levels) >> 8] += 1.0; b += frame.bytesPerLine(); } } else { QImage::Format imageFormat = QVideoFrame::imageFormatFromPixelFormat(frame.pixelFormat()); if (imageFormat != QImage::Format_Invalid) { // Process RGB data QImage image(frame.bits(), frame.width(), frame.height(), imageFormat); image = image.convertToFormat(QImage::Format_RGB32); const QRgb* b = (const QRgb*)image.bits(); for (int y = 0; y < image.height(); y++) { const QRgb *lastPixel = b + frame.width(); for (const QRgb *curPixel = b; curPixel < lastPixel; curPixel++) histogram[(qGray(*curPixel) * levels) >> 8] += 1.0; b = (const QRgb*)((uchar*)b + image.bytesPerLine()); } } } // find maximum value qreal maxValue = 0.0; for (int i = 0; i < histogram.size(); i++) { if (histogram[i] > maxValue) maxValue = histogram[i]; } if (maxValue > 0.0) { for (int i = 0; i < histogram.size(); i++) histogram[i] /= maxValue; } frame.unmap(); } while (false); emit histogramReady(histogram); } #include "histogramwidget.moc"

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