如何使用opencv在qt视频播放期间控制fps？

Question

我尝试使用某些fps（例如30 fps）的opencv控制qt小部件中的视频播放。

有一个问题是我无法控制两个相邻帧之间的播放间隔。由于项目非常复杂，我只是展示一些代码来描述问题：

while(buffer.get(frame))
{
    currentTime = cvGetTickCount();

    waitTime = 1000/fps - (currentTime - lastTime)/msUnit;

    // I hope the thread waiting for 'waitTime' here.

    // I have tried to use QTimer to to control the interval, but it's not
    // accurate at the ms level. Therefore, I tried to use
    // 'QSemaphore.tryAcquire(1, waitTime )', since I have set the 
    // resource to be 0, so 'tryAcquire()' always fails and waited for 
    // expected time. Most of time it worked good, but sometime it didn't, 
    // awaken in later time. 

   lastTime= cvGetTickCount();

   emit NextFrame(frame);
}

换句话说，我希望控制毫秒级的时间间隔。在qt或opencv或其他方面有什么办法吗？

提前致谢！