Qt5 Video Player QtMultimedia QGraphicsVideoItem - c++

Question

Hey stackies currently trying to create some basic code that just plays a video file from local source (as trying to get that working then try and implement rtsp). below is my current code. If anyone can give me an idea where im going wrong that would be great.
Currently the code is failing with the error
C:\Qt\Qt5.1.0\5.1.0\msvc2010_opengl\examples\multimediawidgets\videographicsitem\main.cpp:58: error: C2664: 'QGraphicsScene::addItem' : cannot convert parameter 1 from 'QGraphicsVideoItem *' to 'QGraphicsItem *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
I presume I have to typecast the variable being inserted to additem. However have no idea how to do this with two Qclasses. If someone has an example of a basic player that just contains a video frame and plays the second you start the program ( not even a play button preferably). If anyone has anything like that please let me know as would make my life alot easier.
Main.cpp
#include "videoplayer.h"
#include <QApplication>
#include <QGraphicsView>
int main(int argc, char **argv)
{
QApplication app(argc, argv);
//VideoPlayer player;
//QGraphicsView graphicsView;
QMediaPlayer *player ;
QGraphicsVideoItem *item;
QGraphicsView *graphicsView;
QGraphicsScene *scene;
player->setVideoOutput(item);
// scene->addItem(item);
graphicsView->scene()->addItem(item);
graphicsView->show();
player->setMedia(QUrl("rtsp://192.168.100.58:8554/stream"));
player->play();
graphicsView->show();
return app.exec();
}
Videoplayer.cpp
#include "videoplayer.h"
#include <QtWidgets>
#include <QVideoSurfaceFormat>
#include <QGraphicsVideoItem>
VideoPlayer::VideoPlayer(QWidget *parent)
: QWidget(parent)
, mediaPlayer(0, QMediaPlayer::VideoSurface)
, videoItem(0)
, playButton(0)
, positionSlider(0)
{
videoItem = new QGraphicsVideoItem;
videoItem->setSize(QSizeF(640, 480));
QGraphicsScene *scene = new QGraphicsScene(this);
QGraphicsView *graphicsView = new QGraphicsView(scene);
scene->addItem(videoItem);
QSlider *rotateSlider = new QSlider(Qt::Horizontal);
rotateSlider->setRange(-180, 180);
rotateSlider->setValue(0);
connect(rotateSlider, SIGNAL(valueChanged(int)),
this, SLOT(rotateVideo(int)));
QAbstractButton *openButton = new QPushButton(tr("Open..."));
connect(openButton, SIGNAL(clicked()), this, SLOT(openFile()));
playButton = new QPushButton;
playButton->setEnabled(false);
playButton->setIcon(style()->standardIcon(QStyle::SP_MediaPlay));
connect(playButton, SIGNAL(clicked()),
this, SLOT(play()));
positionSlider = new QSlider(Qt::Horizontal);
positionSlider->setRange(0, 0);
connect(positionSlider, SIGNAL(sliderMoved(int)),
this, SLOT(setPosition(int)));
QBoxLayout *controlLayout = new QHBoxLayout;
controlLayout->setMargin(0);
controlLayout->addWidget(openButton);
controlLayout->addWidget(playButton);
controlLayout->addWidget(positionSlider);
QBoxLayout *layout = new QVBoxLayout;
layout->addWidget(graphicsView);
layout->addWidget(rotateSlider);
layout->addLayout(controlLayout);
setLayout(layout);
mediaPlayer.setVideoOutput(videoItem);
connect(&mediaPlayer, SIGNAL(stateChanged(QMediaPlayer::State)),
this, SLOT(mediaStateChanged(QMediaPlayer::State)));
connect(&mediaPlayer, SIGNAL(positionChanged(qint64)), this, SLOT(positionChanged(qint64)));
connect(&mediaPlayer, SIGNAL(durationChanged(qint64)), this, SLOT(durationChanged(qint64)));
}
VideoPlayer::~VideoPlayer()
{
}
void VideoPlayer::openFile()
{
QString fileName = QFileDialog::getOpenFileName(this, tr("Open Movie"),QDir::homePath());
//QString fileName = "rtsp://192.168.100.58:8554/stream";
if (!fileName.isEmpty()) {
mediaPlayer.setMedia(QUrl::fromLocalFile(fileName));
playButton->setEnabled(true);
}
}
void VideoPlayer::play()
{
switch(mediaPlayer.state()) {
case QMediaPlayer::PlayingState:
mediaPlayer.pause();
break;
default:
mediaPlayer.play();
break;
}
}
Videoplayer.h
#ifndef VIDEOPLAYER_H
#define VIDEOPLAYER_H
#include <QMediaPlayer>
#include <QMovie>
#include <QWidget>
class QAbstractButton;
class QSlider;
class QGraphicsVideoItem;
class VideoPlayer : public QWidget
{
Q_OBJECT
public:
VideoPlayer(QWidget *parent = 0);
~VideoPlayer();
QSize sizeHint() const { return QSize(800, 600); }
public slots:
void openFile();
void play();
private slots:
void mediaStateChanged(QMediaPlayer::State state);
void positionChanged(qint64 position);
void durationChanged(qint64 duration);
void setPosition(int position);
void rotateVideo(int angle);
private:
QMediaPlayer mediaPlayer;
QGraphicsVideoItem *videoItem;
QAbstractButton *playButton;
QSlider *positionSlider;
};
#endif
.pro
TEMPLATE = app
TARGET = videographicsitem
QT += multimedia multimediawidgets
HEADERS += videoplayer.h
SOURCES += main.cpp \
videoplayer.cpp
target.path = $$[QT_INSTALL_EXAMPLES]/multimediawidgets/videographicsitem
INSTALLS += target
QT+=widgets
ALSO just tried this
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QMediaPlayer media;
const QString file = "C:/Users/nick.herniman/Downloads/big_buck_bunny_1080p_h264.mov";
QUrl url(QFileInfo(file).absoluteFilePath());
media.setMedia(url);
media.play();
return a.exec();
}
which works but only plays the audio of the file anyone know what im doing wrong here (does it need to be in a gui window or is it ok for me to just do it in a console application)?

Answer 1

There is nothing weird. :-)
It helps, when the compiler knows, that a QGraphicsVideoItem is a QGraphicsItem. And for the compiler to know this, #include <QGraphicsVideoItem> should be present.
I see, you have it in Videoplayer.cpp. But main.cpp sees only that there is a class QGraphicsVideoItem declared. You did a fine forward declaration. But what this class is... no way to know for the compiler in main.cpp. Add #include <QGraphicsVideoItem> to your main.cpp.

Answer 2

Try this simplest Example in Qt5:
QMediaPlayer *mediaPlayer = new QMediaPlayer(this, QMediaPlayer::VideoSurface);
QGraphicsVideoItem *videoItem = new QGraphicsVideoItem;
videoItem->setPos(100,100);
QGraphicsScene *scene = new QGraphicsScene(this);
ui->GV_VideoPlayer->setScene(scene);
scene->addItem(videoItem);
QString fileName = "/root/sampleVideos/videoplayback.mp4";
if(!fileName.isEmpty())
{
mediaPlayer->setMedia(QUrl::fromLocalFile(fileName));
}
mediaPlayer->play();
mediaPlayer->setVideoOutput(videoItem);

Answer 3

It is actually really weird that the QT documentation states a very similar example ( http://qt-project.org/doc/qt-5.0/qtmultimedia/qgraphicsvideoitem.html ), while the objects are actually not related. Apart from that, just looking through the QT documentation since I haven't worked with QT for a while - does creating a dummy QGraphicsItem, setting it as a parent to your QGraphicsVideoItem and then adding that dummy item to the scene help? I guess it would go something like this
QGraphicsItem* dummy = new QGraphicsItem;
item = new QGraphicsVideoItem(dummy);
graphicsView->scene()->addItem(dummy);