cv::imshow("video", *frame);

这段代码使用OpenCV库中的imshow函数来展示图像或视频帧。其中，第一个参数是窗口名称，第二个参数是指向图像或视频帧的指针。如果你在程序中读取视频文件，那么这个指针就是从视频中读取到的帧。如果你在程序中捕捉摄像头，则需要使用cv::VideoCapture类来捕捉摄像头帧，然后将其传递给imshow函数。请注意，imshow函数只能在图形界面中运行的情况下使用，如果你在命令行中运行程序，则无法显示图像。

相关问题

error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'

This error occurs when the width of an image or video frame is reported as zero or negative. It is typically caused by passing an empty or invalid image or video frame to a function that requires a valid frame with positive dimensions.

To fix this error, you should check the input data and ensure that it is valid before passing it to any function that requires a valid frame or image. This may involve adding error handling code to your application to detect and handle invalid input data, or modifying your code to generate valid input data.

error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'cv::imshow'什么意思

This error message is related to OpenCV and it usually occurs when an image or video frame with an invalid size (width or height is zero or negative) is passed as input to a function that expects a valid size. To fix this error, you need to check the dimensions of your image or video frames before passing them as input to any OpenCV function that requires a valid size. You can use the `shape` attribute of numpy arrays or the `size()` method of OpenCV `Mat` objects to check the dimensions of your input data. Also, make sure that your video capture device or file is properly initialized and that you are reading valid frames from it.