include QFile include QPair include QImage include QColor include QDeb

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#include <QFile>
#include <QPair>
#include <QImage>
#include <QColor>
#include <QDebug>
#include <QTemporaryFile>
#include <QApplication>
#include "videopreviewcreator.h"
VideoPreviewCreator::VideoPreviewCreator()
{
}
QByteArray VideoPreviewCreator::getImageData(fas_raw_image_type *image)
{
QByteArray res;
res.append(QString("P6\n%1 %2\n255\n").arg(image->width).arg(image->height));
// Write pixel data
for(int h=0; h<image->height; h++)
for(int w=0; w<image->width*3; w++)
res.append(*(image->data + h * image->bytes_per_line+w));
return res;
}
static void ppm_save(fas_raw_image_type *image, char *filename)
{
FILE *f;
int i;
if (image->color_space != FAS_RGB24) {
return;
}
f=fopen(filename,"wb");
fprintf(f,"P6\n%d %d\n%d\n", image->width, image->height, 255);
for(i=0; i<image->height; i++) {
fwrite(image->data + i * image->bytes_per_line, 1, image->width * 3, f);
}
fclose(f);
}
QVector<int> VideoPreviewCreator::getHistogram(QImage img)
{
QVector<int> hist;
hist.fill(0, 768);
for(int i=0; i<img.width(); i++)
for(int j=0; j<img.height(); j++)
{
QColor color;
color.setRgb(img.pixel(i, j));
hist[color.red()] += 1;
hist[color.green()+256] += 1;
hist[color.blue()+512] += 1;
}
return hist;
}
QVector<qint64> VideoPreviewCreator::getMedian(QVector<QPair<QVector<int>, int> > hists)
{
QVector<qint64> median;
median.fill(0, 768);
for (int i=0; i<hists.size(); i++)
for (int j=0; j<768; j++)
median[j] += hists[i].first[j];
for(int i=0; i<768; i++)
median[i] /= hists.size();
return median;
}
QPair<QVector<int>, int> VideoPreviewCreator::getClosest(QVector<QPair<QVector<int>, int> > hists, QVector<qint64> median)
{
QVector<qint64> diffs;
diffs.fill(0, hists.size());
for (int i=0; i< hists.size(); i++)
{
QVector<int> hist = hists[i].first;
qint64 sum = 0;
for(int j=0; j<768; j++)
sum += (median[j]-hist[j])*(median[j]-hist[j]);
diffs[i] = sum;
}
qint64 min = Q_INT64_C(932838457459459);
int min_n = diffs.size();
for(int i=0; i<diffs.size(); i++)
if (diffs[i]<min)
{
min = diffs[i];
min_n = i;
}
return hists.at(min_n);
}
QImage VideoPreviewCreator::getPreview(QString filename)
{
fas_error_type video_error;
fas_context_ref_type context;
fas_raw_image_type image_buffer;
fas_initialize (FAS_FALSE, FAS_RGB24);
video_error = fas_open_video (&context, (char*)filename.toStdString().c_str());
if (video_error != FAS_SUCCESS)
{
qDebug() << "failed to open video file";
return QImage();
}
QByteArray res;
int counter = 0;
QVector<QPair<QVector<int>, int> > hists;
bool error = false;
while (counter < 75)
{
if (FAS_SUCCESS != fas_get_frame (context, &image_buffer))
{
error = true;
break;
}
QImage img;
if (!img.loadFromData(getImageData(&image_buffer)))
{
error = true;
break;
}
hists.append(qMakePair(getHistogram(img), counter));
fas_free_frame (image_buffer);
if (FAS_SUCCESS != fas_step_forward (context))
{
error = true;
break;
}
counter++;
}
if (error) return QImage();
QPair<QVector<int>, int> frame = getClosest(hists, getMedian(hists));
fas_seek_to_frame(context, frame.second);
fas_get_frame (context, &image_buffer);
QImage img;
img.loadFromData(getImageData(&image_buffer));
fas_free_frame (image_buffer);
return img;
}