vlc-qt获取视频的每一帧

/*
*   qt获取视频的每一帧
*/

#include <QtCore/QCoreApplication>
#include <Windows.h>  
#include "vlc/vlc.h"  
#include <qmutex>
#include <qimage>
#pragma comment(lib,"libvlc.lib")
#pragma comment(lib,"libvlccore.lib")
QMutex g_mutex;
int IMG_WIDTH = 512;
int IMG_HEIGHT = 280;
int frameNum = 0;

//opaque为libvlc_video_set_callbacks回调最后一个参数传递的指针
static void* lock(void* opaque, void** planes)
{
    
    
    char* buffer = (char*)opaque;
    g_mutex.lock();
    *planes = buffer;           /*tell VLC to put decoded data to this buffer*/
    return 0;                   /* picture identifier, not needed here */
}

/*##get the argb picture AND save to file*/
static void unlock(void* opaque, void* picture, void* const* planes)
{
    
    
    char* buffer = (char*)opaque;
    QImage image((unsigned char*)buffer, IMG_WIDTH, IMG_HEIGHT, QImage::Format_ARGB32);
    QString filePath;
    filePath.sprintf("d:/img%d.jpg", frameNum);
    frameNum++;
    image.save(filePath);
    g_mutex.unlock();
}

static void display(void* opaque, void* picture)
{
    
    
    (void)opaque;
}

int main(int argc, char *argv[])
{
    
    
    libvlc_instance_t* inst;
    libvlc_media_player_t* mp;
    libvlc_media_t* m;

    libvlc_time_t length;
    int wait_time = 5000;

    /* Load the VLC engine */
    inst = libvlc_new(NULL, NULL); 

    m = libvlc_media_new_path(inst, "cuc_ieschool.flv");
    mp = libvlc_media_player_new_from_media(m);

    libvlc_media_release(m);
    
    char* buffer = (char*)malloc(640 * 480 * 4);
    libvlc_video_set_callbacks(mp, lock, unlock, display, buffer);
    libvlc_video_set_format(mp, "RGBA", IMG_WIDTH, IMG_HEIGHT, IMG_WIDTH * 4);

    libvlc_media_player_play(mp);

    _sleep(wait_time);
    length = libvlc_media_player_get_length(mp);
    IMG_WIDTH = libvlc_video_get_width(mp);
    IMG_HEIGHT = libvlc_video_get_height(mp);
    printf("Stream Duration: %ds\n", length / 1000);
    printf("Resolution: %d x %d\n", IMG_WIDTH, IMG_HEIGHT);

    //Let it play   
    _sleep(length - wait_time);

    // Stop playing  
    libvlc_media_player_stop(mp);

    // Free the media_player  
    libvlc_media_player_release(mp);

    libvlc_release(inst);
    free(buffer);
}