解决： WARN:0] global ./modules/videoio/src/cap_gstreamer.cpp (1100) open OpenCV | GStreamer warning:

更换主机后莫名出现的错误，连接不上摄像头，但查询usb摄像头是有0和1的

错误：

[ WARN:0] global ./modules/videoio/src/cap_gstreamer.cpp (2075) handleMessage OpenCV | GStreamer warning: Embedded video playback halted; module v4l2src0 reported: Device '/dev/video1' is not a capture device.
[ WARN:0] global ./modules/videoio/src/cap_gstreamer.cpp (1053) open OpenCV | GStreamer warning: unable to start pipeline
[ WARN:0] global ./modules/videoio/src/cap_gstreamer.cpp (616) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created
[ WARN:0] global ./modules/videoio/src/cap_v4l.cpp (890) open VIDEOIO(V4L2:/dev/video1): can't open camera by index

原代码：

    cv::VideoCapture cap(0);
    if(!cap.isOpened()) {
        logEvent("无法打开摄像头");
        return -1;
    }
    logEvent("摄像头打开成功");

利用ubuntu自带的cheese试图查看画面，发现系统未检测到摄像头(或者是别的什么提示，有点记不清了）

查询后发现一个及其有效的方法：把0改成-1就解决了

    cv::VideoCapture cap(-1);
    if(!cap.isOpened()) {
        logEvent("无法打开摄像头");
        return -1;
    }
    logEvent("摄像头打开成功");

😺😺😺