LibVLC SampleCode Qt

2012-01-09T13:32:58Z

Bedduzzo: Little code error

This sample code will render a video into a Qt QWidget.

This was tested with vlc-0.9.9 and Qt 4.5.1 on WinXP and Linux

== How to use? ==

You need [[LibVLC|''libvlc headers'']] and ''Qt headers''.Take those 3 files, put them in a folder.
Run
qmake -project

Edit the .pro file and add
LIBS += -L*path to vlc lib* #if you are at windows os
LIBS += -lvlc

Run
qmake
and then
make or mingw32-make under a Windows OS

On win os you have to use the zip file. the lib and the header files are located in the sdk-folder.

== VLC 1.1.5 and Ubutnu Lucid ==
[Ondrej Spilka 20101201] slightly modified for the modest versions...
- tested ok
- X11 embed container have to be used, therefore QX11EmbedContainer rather than QFrame have to be used.

== Files ==

main.cpp:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/

#include "vlc_on_qt.h"
#include <QtGui/QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Player p;
p.resize(640,480);
p.playFile("rtp://@:2626"); // Replace with what you want to play
p.show();
return a.exec();
}
</pre>

vlc_on_qt.h:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/
#ifndef VLC_ON_QT_H
#define VLC_ON_QT_H

#include <vlc/vlc.h>

#include <QWidget>

class QVBoxLayout;
class QPushButton;
class QTimer;
class QFrame;
class QSlider;

#define POSITION_RESOLUTION 10000

class Player : public QWidget
{
Q_OBJECT
QSlider *_positionSlider;
QSlider *_volumeSlider;
// [20101201 Ondra Spilka]
// on Linux/Ubuntu Lucid and VLC >= 1.0 (at least 1.1.5 was tested) XWindow handle have to be passed
// therefore QX11EmbedContainer have to be used instead of QFrame
#ifdef Q_WS_X11
QX11EmbedContainer *_videoWidget;
#else
QFrame *_videoWidget;
#endif
QTimer *poller;
bool _isPlaying;
libvlc_exception_t _vlcexcep;
libvlc_instance_t *_vlcinstance;
libvlc_media_player_t *_mp;
libvlc_media_t *_m;

public:
Player();
~Player();
void raise(libvlc_exception_t * ex);

public slots:
void playFile(QString file);
void updateInterface();
void changeVolume(int newVolume);
void changePosition(int newPosition);

};
#endif
</pre>

vlc_on_qt.cpp:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/
#include "vlc_on_qt.h"

#include <QVBoxLayout>
#include <QPushButton>
#include <QSlider>
#include <QTimer>
#include <QFrame>

Player::Player()
: QWidget()
{
//preparation of the vlc command
const char * const vlc_args[] = {
"-I", "dummy", /* Don't use any interface */
"--ignore-config", /* Don't use VLC's config */
"--extraintf=logger", //log anything
"--verbose=2", //be much more verbose then normal for debugging purpose
"--plugin-path=C:\\vlc-0.9.9-win32\\plugins\\" };

#ifdef Q_WS_X11
_videoWidget=new QX11EmbedContainer(this);
#else
_videoWidget=new QFrame(this);
#endif

_volumeSlider=new QSlider(Qt::Horizontal,this);
_volumeSlider->setMaximum(100); //the volume is between 0 and 100
_volumeSlider->setToolTip("Audio slider");

// Note: if you use streaming, there is no ability to use the position slider
_positionSlider=new QSlider(Qt::Horizontal,this);
_positionSlider->setMaximum(POSITION_RESOLUTION);

QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(_videoWidget);
layout->addWidget(_positionSlider);
layout->addWidget(_volumeSlider);
setLayout(layout);

_isPlaying=false;
poller=new QTimer(this);

//Initialize an instance of vlc
//a structure for the exception is neede for this initalization
libvlc_exception_init(&_vlcexcep);

//create a new libvlc instance
_vlcinstance=libvlc_new(sizeof(vlc_args) / sizeof(vlc_args[0]), vlc_args,&_vlcexcep); //tricky calculation of the char space used
raise (&_vlcexcep);

// Create a media player playing environement
_mp = libvlc_media_player_new (_vlcinstance, &_vlcexcep);
raise (&_vlcexcep);

//connect the two sliders to the corresponding slots (uses Qt's signal / slots technology)
connect(poller, SIGNAL(timeout()), this, SLOT(updateInterface()));
connect(_positionSlider, SIGNAL(sliderMoved(int)), this, SLOT(changePosition(int)));
connect(_volumeSlider, SIGNAL(sliderMoved(int)), this, SLOT(changeVolume(int)));

poller->start(100); //start timer to trigger every 100 ms the updateInterface slot
}

//desctructor
Player::~Player()
{
/* Stop playing */
libvlc_media_player_stop (_mp, &_vlcexcep);

/* Free the media_player */
libvlc_media_player_release (_mp);

libvlc_release (_vlcinstance);
raise (&_vlcexcep);
}

void Player::playFile(QString file)
{
//the file has to be in one of the following formats /perhaps a little bit outdated)
/*
[file://]filename Plain media file
http://ip:port/file HTTP URL
ftp://ip:port/file FTP URL
mms://ip:port/file MMS URL
screen:// Screen capture
[dvd://][device][@raw_device] DVD device
[vcd://][device] VCD device
[cdda://][device] Audio CD device
udp:[[<source address>]@[<bind address>][:<bind port>]]
*/

/* Create a new LibVLC media descriptor */
_m = libvlc_media_new (_vlcinstance, file.toAscii(), &_vlcexcep);
raise(&_vlcexcep);

libvlc_media_player_set_media (_mp, _m, &_vlcexcep);
raise(&_vlcexcep);

// /!\ Please note /!\
//
// passing the widget to the lib shows vlc at which position it should show up
// vlc automatically resizes the video to the ´given size of the widget
// and it even resizes it, if the size changes at the playing

/* Get our media instance to use our window */
#if defined(Q_OS_WIN)
libvlc_media_player_set_drawable(_mp, reinterpret_cast<unsigned int>(_videoWidget->winId()), &_vlcexcep );
//libvlc_media_player_set_hwnd(_mp, _videoWidget->winId(), &_vlcexcep ); // for vlc 1.0
#elif defined(Q_OS_MAC)
libvlc_media_player_set_drawable(_mp, _videoWidget->winId(), &_vlcexcep );
//libvlc_media_player_set_agl (_mp, _videoWidget->winId(), &_vlcexcep); // for vlc 1.0
#else //Linux
//[20101201 Ondrej Spilka] obsolete call on libVLC >=1.1.5
//libvlc_media_player_set_drawable(_mp, _videoWidget->winId(), &_vlcexcep );
//libvlc_media_player_set_xwindow(_mp, _videoWidget->winId(), &_vlcexcep ); // for vlc 1.0

/* again note X11 handle on Linux is needed
winID() returns X11 handle when QX11EmbedContainer us used */

int windid = _videoWidget->winId();
libvlc_media_player_set_xwindow (mp, windid );

#endif
raise(&_vlcexcep);

/* Play */
libvlc_media_player_play (_mp, &_vlcexcep );
raise(&_vlcexcep);

_isPlaying=true;
}

void Player::changeVolume(int newVolume)
{
libvlc_exception_clear(&_vlcexcep);
libvlc_audio_set_volume (_vlcinstance,newVolume , &_vlcexcep);
raise(&_vlcexcep);
}

void Player::changePosition(int newPosition)
{
libvlc_exception_clear(&_vlcexcep);
// It's possible that the vlc doesn't play anything
// so check before
libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp, &_vlcexcep);
libvlc_exception_clear(&_vlcexcep);
if (curMedia == NULL)
return;

float pos=(float)(newPosition)/(float)POSITION_RESOLUTION;
libvlc_media_player_set_position (_mp, pos, &_vlcexcep);
raise(&_vlcexcep);
}

void Player::updateInterface()
{
if(!_isPlaying)
return;

// It's possible that the vlc doesn't play anything
// so check before
libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp, &_vlcexcep);
libvlc_exception_clear(&_vlcexcep);
if (curMedia == NULL)
return;

float pos=libvlc_media_player_get_position (_mp, &_vlcexcep);
int siderPos=(int)(pos*(float)(POSITION_RESOLUTION));
_positionSlider->setValue(siderPos);
int volume=libvlc_audio_get_volume (_vlcinstance,&_vlcexcep);
_volumeSlider->setValue(volume);
}
void Player::raise(libvlc_exception_t * ex)
{
if (libvlc_exception_raised (ex))
{
fprintf (stderr, "error: %s\n", libvlc_exception_get_message(ex));
exit (-1);
}
}
</pre>

== VLC 1.2 and OpenSuse 11.3 ==
[Jofre Guevara 20101215] Modifications of original template based on new VLC version.
[Ondrej Spilka 20101201] slightly modified for the modest versions...
- tested ok

== Files ==

main.cpp:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/

#include "vlc_on_qt.h"
#include <QtGui/QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Player p;
p.resize(640,480);
p.playFile("rtp://@:2626"); // Replace with what you want to play
p.show();
return a.exec();
}
</pre>

vlc_on_qt.h:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/
#ifndef VLC_ON_QT_H
#define VLC_ON_QT_H

#include <vlc/vlc.h>

#include <QWidget>

class QVBoxLayout;
class QPushButton;
class QTimer;
class QFrame;
class QSlider;

#define POSITION_RESOLUTION 10000

class Player : public QWidget
{
Q_OBJECT
QSlider *_positionSlider;
QSlider *_volumeSlider;
// [20101215 JG]
// Tested on Linux OpenSuse and VLC 1.2.0. This version of VLC is not completely compatible with previous versions of VLC.
// [20101201 Ondra Spilka]
// on Linux/Ubuntu Lucid and VLC >= 1.0 (at least 1.1.5 was tested) XWindow handle have to be passed
// therefore QX11EmbedContainer have to be used instead of QFrame
#ifdef Q_WS_X11
QX11EmbedContainer *_videoWidget;
#else
QFrame *_videoWidget;
#endif
// [20101215 JG] If KDE is used like unique desktop environment, only use QFrame *_videoWidget;
QTimer *poller;
bool _isPlaying;
//libvlc_exception_t _vlcexcep; // [20101215 JG] Used for versions prior to VLC 1.2.0.
libvlc_instance_t *_vlcinstance;
libvlc_media_player_t *_mp;
libvlc_media_t *_m;

public:
Player();
~Player();
//void raise(libvlc_exception_t * ex); // [20101215 JG] Used for versions prior to VLC 1.2.0.

public slots:
void playFile(QString file);
void updateInterface();
void changeVolume(int newVolume);
void changePosition(int newPosition);

};
#endif
</pre>

vlc_on_qt.cpp:
<pre>
/* libVLC and Qt sample code
* Copyright © 2009 Alexander Maringer <maringer@maringer-it.de>
*/
#include "vlc_on_qt.h"

#include <QVBoxLayout>
#include <QPushButton>
#include <QSlider>
#include <QTimer>
#include <QFrame>

Player::Player()
: QWidget()
{
//preparation of the vlc command
const char * const vlc_args[] = {
"-I", "dummy", /* Don't use any interface */
"--ignore-config", /* Don't use VLC's config */
"--extraintf=logger", //log anything
"--verbose=2", //be much more verbose then normal for debugging purpose
"--plugin-path=C:\\vlc-0.9.9-win32\\plugins\\" };

#ifdef Q_WS_X11
_videoWidget=new QX11EmbedContainer(this);
#else
_videoWidget=new QFrame(this);
#endif
// [20101215 JG] If KDE is used like unique desktop environment, only use _videoWidget=new QFrame(this);

_volumeSlider=new QSlider(Qt::Horizontal,this);
_volumeSlider->setMaximum(100); //the volume is between 0 and 100
_volumeSlider->setToolTip("Audio slider");

// Note: if you use streaming, there is no ability to use the position slider
_positionSlider=new QSlider(Qt::Horizontal,this);
_positionSlider->setMaximum(POSITION_RESOLUTION);

QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(_videoWidget);
layout->addWidget(_positionSlider);
layout->addWidget(_volumeSlider);
setLayout(layout);

_isPlaying=false;
poller=new QTimer(this);

//Initialize an instance of vlc
//a structure for the exception is neede for this initalization
//libvlc_exception_init(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

//create a new libvlc instance
_vlcinstance=libvlc_new(sizeof(vlc_args) / sizeof(vlc_args[0]), vlc_args); //tricky calculation of the char space used
//_vlcinstance=libvlc_new(sizeof(vlc_args) / sizeof(vlc_args[0]), vlc_args,&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise (&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

// Create a media player playing environement
_mp = libvlc_media_player_new (_vlcinstance);
//_mp = libvlc_media_player_new (_vlcinstance, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise (&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

//connect the two sliders to the corresponding slots (uses Qt's signal / slots technology)
connect(poller, SIGNAL(timeout()), this, SLOT(updateInterface()));
connect(_positionSlider, SIGNAL(sliderMoved(int)), this, SLOT(changePosition(int)));
connect(_volumeSlider, SIGNAL(sliderMoved(int)), this, SLOT(changeVolume(int)));

poller->start(100); //start timer to trigger every 100 ms the updateInterface slot
}

//desctructor
Player::~Player()
{
/* Stop playing */
libvlc_media_player_stop (_mp);
//libvlc_media_player_stop (_mp, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

/* Free the media_player */
libvlc_media_player_release (_mp);

libvlc_release (_vlcinstance);
//raise (&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
}

void Player::playFile(QString file)
{
//the file has to be in one of the following formats /perhaps a little bit outdated)
/*
[file://]filename Plain media file
http://ip:port/file HTTP URL
ftp://ip:port/file FTP URL
mms://ip:port/file MMS URL
screen:// Screen capture
[dvd://][device][@raw_device] DVD device
[vcd://][device] VCD device
[cdda://][device] Audio CD device
udp:[[<source address>]@[<bind address>][:<bind port>]]
*/

/* Create a new LibVLC media descriptor */
_m = libvlc_media_new_path(_vlcinstance, file.toAscii());
//_m = libvlc_media_new (_vlcinstance, file.toAscii(), &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

libvlc_media_player_set_media (_mp, _m);
//libvlc_media_player_set_media (_mp, _m, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

// /!\ Please note /!\
//
// passing the widget to the lib shows vlc at which position it should show up
// vlc automatically resizes the video to the ´given size of the widget
// and it even resizes it, if the size changes at the playing

/* Get our media instance to use our window */
#if defined(Q_OS_WIN)
libvlc_media_player_set_drawable(_mp, reinterpret_cast<unsigned int>(_videoWidget->winId()));
//libvlc_media_player_set_drawable(_mp, reinterpret_cast<unsigned int>(_videoWidget->winId()), &_vlcexcep ); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//libvlc_media_player_set_hwnd(_mp, _videoWidget->winId(), &_vlcexcep ); // for vlc 1.0
#elif defined(Q_OS_MAC)
libvlc_media_player_set_drawable(_mp, _videoWidget->winId());
//libvlc_media_player_set_drawable(_mp, _videoWidget->winId(), &_vlcexcep ); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//libvlc_media_player_set_agl (_mp, _videoWidget->winId(), &_vlcexcep); // for vlc 1.0
#else //Linux
//[20101201 Ondrej Spilka] obsolete call on libVLC >=1.1.5
//libvlc_media_player_set_drawable(_mp, _videoWidget->winId(), &_vlcexcep );
//libvlc_media_player_set_xwindow(_mp, _videoWidget->winId(), &_vlcexcep ); // for vlc 1.0

/* again note X11 handle on Linux is needed
winID() returns X11 handle when QX11EmbedContainer us used */

int windid = _videoWidget->winId();
libvlc_media_player_set_xwindow (_mp, windid );

#endif
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

/* Play */
libvlc_media_player_play (_mp);
//libvlc_media_player_play (_mp, &_vlcexcep ); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.

_isPlaying=true;
}

void Player::changeVolume(int newVolume)
{
//libvlc_exception_clear(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
libvlc_audio_set_volume (_mp,newVolume);
//libvlc_audio_set_volume (_vlcinstance,newVolume , &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
}

void Player::changePosition(int newPosition)
{
//libvlc_exception_clear(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
// It's possible that the vlc doesn't play anything
// so check before
libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp);
//libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//libvlc_exception_clear(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
if (curMedia == NULL)
return;

float pos=(float)(newPosition)/(float)POSITION_RESOLUTION;
libvlc_media_player_set_position (_mp, pos);
//libvlc_media_player_set_position (_mp, pos, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//raise(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
}

void Player::updateInterface()
{
if(!_isPlaying)
return;

// It's possible that the vlc doesn't play anything
// so check before
libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp);
//libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
//libvlc_exception_clear(&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
if (curMedia == NULL)
return;

float pos=libvlc_media_player_get_position (_mp);
//float pos=libvlc_media_player_get_position (_mp, &_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
int siderPos=(int)(pos*(float)(POSITION_RESOLUTION));
_positionSlider->setValue(siderPos);
int volume=libvlc_audio_get_volume (_mp);
//int volume=libvlc_audio_get_volume (_vlcinstance,&_vlcexcep); // [20101215 JG] Used for versions prior to VLC 1.2.0.
_volumeSlider->setValue(volume);
}
/*void Player::raise(libvlc_exception_t * ex)
{
if (libvlc_exception_raised (ex))
{
fprintf (stderr, "error: %s\n", libvlc_exception_get_message(ex));
exit (-1);
}
}*/ // [20101215 JG] Used for versions prior to VLC 1.2.0.
</pre>

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