基于QT视频软件的开发和学习

1、基于QT视频软件的开发和学习 马上工作需要做视频软件了，所以准备学习QT来开发，为什么选择QT呢，因为他优点多多（不说了自己网上g一下） 随着高清的不断普及，所有视频软件都向高清这个方向而前进，其中有一款开源跨平台的播放器vlc的特性和功能都是非常的好，所以想准备学习vlc的源码来看看，在看他源码的时候，发现他还有一个可供开发人员调用的libvlc 媒体库可用(GPL)，而vlc本身使用的GUI就是QT。 好了不多说了 先装好QT SDK，然后把环境变量设置一下（不会去G!） 然后把vlc库加入到mingw里面 先复制vlc-include.rar解压出来的头文件到Qt2009.04mingw

2、include里面 在把vlc-lib.rar解压出来的文件放到C:vlc-lib 我们在 Qt Creator 里面建立一个空的QT项目 新建一个Player类 ,会多出player.cpp,player.h 修改成如下player.cppCpp代码 /* * Flie Name player.cpp */ #include player.h #include <QVBoxLayout> #include <QPushButton> #include <QSlider> #include <QTimer> #include <QFrame

3、> Player:Player() : QWidget() /preparation of the vlc command const char * const vlc_args = -I, dummy, /* Dont use any interface */ -ignore-config, /* Dont use VLCs config */ -extraintf=logger, /log anything -verbose=2, /be much more verbose then normal for debugging purpose -plugin-path=C:vlc-0.

4、9.9-win32plugins ; _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 _positionSlide

5、r=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);

6、 /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_args0), vlc_args,&_vlcexcep); /tricky calculation of the char space used raise

7、 (&_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 Qts signal / slots technology) connect(poller, SIGNAL(timeout(), this, SLOT(updateInterface(

8、); 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 */ libv

9、lc_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 P

10、lain media file http:/ip:port/file HTTP URL ftp:/ip:port/file FTP URL mms:/ip:port/file MMS URL screen:/ Screen capture dvd:/deviceraw_device DVD device vcd:/device VCD device cdda:/device Audio CD device udp:<source address><bind address>:<bind port> */ /* Create a new LibVLC medi

11、a 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 autom

12、atically 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(), &_vlce

13、xcep ); /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 #

14、else /Linux libvlc_media_player_set_drawable(_mp, _videoWidget->winId(), &_vlcexcep ); /libvlc_media_player_set_xwindow(_mp, _videoWidget->winId(), &_vlcexcep ); / for vlc 1.0 #endif raise(&_vlcexcep); /* Play */ libvlc_media_player_play (_mp, &_vlcexcep ); raise(&_vlcexcep

15、); _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); / Its possible that the vl

16、c doesnt 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, &_v

17、lcexcep); raise(&_vlcexcep); void Player:updateInterface() if(!_isPlaying) return; / Its possible that the vlc doesnt play anything / so check before libvlc_media_t *curMedia = libvlc_media_player_get_media (_mp, &_vlcexcep); libvlc_exception_clear(&_vlcexcep); if (curMedia = NULL) retur

18、n; 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

19、 * ex) if (libvlc_exception_raised (ex) fprintf (stderr, error: %sn, libvlc_exception_get_message(ex); exit (-1); player.hCpp代码 /* libVLC and Qt sample code * Copyright ? 2009 Alexander Maringer <maringermaringer-it.de> */ #ifndef VLC_ON_QT_H #define VLC_ON_QT_H #include <vlc/vlc.h> #inc

20、lude <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; QFrame *_videoWidget; 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); publi