File indexing completed on 2024-05-12 04:54:57

 /*
     SPDX-FileCopyrightText: 2006-2008 Marco Gulino <marco@kmobiletools.org>
     SPDX-FileCopyrightText: Jean-Baptiste Mardelle <jb@kdenlive.org>
 
     SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
 */
 
 #include "mltpreview.h"
 #include "../src/lib/localeHandling.h"
 
 #include <QDebug>
 #include <QImage>
 #include <QVarLengthArray>
 #include <QtGlobal>
 
 extern "C" {
 Q_DECL_EXPORT ThumbCreator *new_creator()
 {
     return new MltPreview;
 }
 }
 
 MltPreview::MltPreview()
 {
     // After initialising the MLT factory, set the locale back from user default to C
     // to ensure numbers are always serialised with . as decimal point.
     Mlt::Factory::init();
     LocaleHandling::resetLocale();
 }
 
 MltPreview::~MltPreview()
 {
     Mlt::Factory::close();
 }
 
 bool MltPreview::create(const QString &path, int width, int height, QImage &img)
 {
     std::unique_ptr<Mlt::Profile> profile(new Mlt::Profile());
     std::shared_ptr<Mlt::Producer> producer(new Mlt::Producer(*profile.get(), path.toUtf8().data()));
 
     if (producer->is_blank()) {
         return false;
     }
     int frame = 75;
     uint variance = 10;
     int ct = 1;
     double ar = profile->dar();
     if (ar < 1e-6) {
         ar = 1.0;
     }
     int wanted_width = width;
     int wanted_height = int(width / profile->dar());
     if (wanted_height > height) {
         wanted_height = height;
         wanted_width = int(height * ar);
     }
     // We don't need audio
     producer->set("audio_index", -1);
 
     // Add normalizers
     Mlt::Filter scaler(*profile.get(), "swscale");
     Mlt::Filter padder(*profile.get(), "resize");
     Mlt::Filter converter(*profile.get(), "avcolor_space");
 
     if (scaler.is_valid()) {
         producer->attach(scaler);
     }
     if (padder.is_valid()) {
         producer->attach(padder);
     }
     if (converter.is_valid()) {
         producer->attach(converter);
     }
 
     // img = getFrame(producer, frame, width, height);
     while (variance <= 40 && ct < 4) {
         img = getFrame(producer, frame, wanted_width, wanted_height);
         variance = uint(imageVariance(img));
         frame += 100 * ct;
         ct++;
     }
     return (!img.isNull());
 }
 
 QImage MltPreview::getFrame(std::shared_ptr<Mlt::Producer> producer, int framepos, int width, int height)
 {
     QImage mltImage(width, height, QImage::Format_ARGB32);
     if (producer == nullptr) {
         return mltImage;
     }
 
     producer->seek(framepos);
     Mlt::Frame *frame = producer->get_frame();
     if (frame == nullptr || !frame->is_valid()) {
         return mltImage;
     }
 
     mlt_image_format format = mlt_image_rgba;
     const uchar *imagedata = frame->get_image(format, width, height);
     if (imagedata != nullptr) {
         memcpy(mltImage.bits(), imagedata, size_t(width * height * 4));
         mltImage = mltImage.rgbSwapped();
     }
 
     delete frame;
     return mltImage;
 }
 
 int MltPreview::imageVariance(const QImage &image)
 {
     if (image.isNull()) {
         return 0;
     }
     int delta = 0;
     int avg = 0;
     int bytes = int(image.sizeInBytes());
     int STEPS = bytes / 2;
     if (STEPS < 1) {
         return 0;
     }
     QVarLengthArray<uchar> pivot(STEPS);
     qDebug() << "Using " << STEPS << " steps\n";
     const uchar *bits = image.bits();
     // First pass: get pivots and taking average
     for (int i = 0; i < STEPS; i++) {
         pivot[i] = bits[2 * i];
         avg += pivot.at(i);
     }
     avg = avg / STEPS;
     // Second Step: calculate delta (average?)
     for (int i = 0; i < STEPS; ++i) {
         int curdelta = abs(avg - pivot.at(i));
         delta += curdelta;
     }
     return delta / STEPS;
 }
 
 ThumbCreator::Flags MltPreview::flags() const
 {
     return None;
 }