OpenCV:读取视频序列 [英] OpenCV: Reading video sequences

问题描述

是否有一种在OpenCV中随机读取视频帧的方法?就像使用索引访问数组一样?否则，如果我想在CPU或GPU中加载完整的视频，该怎么办?

Is there a way of randomly reading video frames in OpenCV....just like arrays are accessed using indexes? Otherwise, if I want to load complete video in CPU or GPU how can I do it?

推荐答案

您可以在视频捕获中使用set(int propId, double value)方法(另请参阅

You can use the set(int propId, double value) method on your video capture (also check out the documentation), where propId can either be one of the following:

• CV_CAP_PROP_POS_MSEC:视频文件的当前位置，以毫秒为单位.
• CV_CAP_PROP_POS_FRAMES:接下来要解码/捕获的帧的从0开始的索引.
• CV_CAP_PROP_POS_AVI_RATIO:视频文件的相对位置:0-电影的开始，1-电影的结束.

• CV_CAP_PROP_POS_MSEC: Current position of the video file in milliseconds.
• CV_CAP_PROP_POS_FRAMES: 0-based index of the frame to be decoded/captured next.
• CV_CAP_PROP_POS_AVI_RATIO: Relative position of the video file: 0 - start of the film, 1 - end of the film.

一个播放视频50秒的小例子:

A small example that plays a video 50 seconds in:

int main( int argc, char **argv )
{
    namedWindow("Frame", CV_WINDOW_NORMAL);
    Mat frame;

    VideoCapture capture(argv[1]);
    if (!capture.isOpened())
    {
        //error in opening the video input
        cerr << "Unable to open video file: " << argv[1] << endl;
        exit(EXIT_FAILURE);
    }

    capture.set(CV_CAP_PROP_POS_MSEC, 50000);
    for (;;)
    {
        //read the current frame
        if (!capture.read(frame))
        {
            cerr << "Unable to read next frame." << endl;
            cerr << "Exiting program!" << endl;
            exit(EXIT_FAILURE);
        }
        imshow("Frame", frame);
        waitKey(20);
    }
}

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