使用Opencv c++从视频文件中保存10秒的视频

#include <opencv2/opencv.hpp>

cv::VideoCapture video("video_file_path");
if (!video.isOpened()) {
    // 处理视频文件打开失败的情况
}

double fps = video.get(cv::CAP_PROP_FPS);
int totalFrames = video.get(cv::CAP_PROP_FRAME_COUNT);

int saveFrames = 10 * fps; // 10秒的帧数
if (saveFrames > totalFrames) {
    saveFrames = totalFrames; // 如果视频时长不足10秒，则保存全部帧数
}

cv::VideoWriter writer("output_file_path", cv::VideoWriter::fourcc('M', 'J', 'P', 'G'), fps, cv::Size(video.get(cv::CAP_PROP_FRAME_WIDTH), video.get(cv::CAP_PROP_FRAME_HEIGHT)));
if (!writer.isOpened()) {
    // 处理视频编写器创建失败的情况
}

cv::Mat frame;
int frameCount = 0;
while (frameCount < saveFrames && video.read(frame)) {
    writer.write(frame);
    frameCount++;
}

video.release();
writer.release();