具有“ int main（int argc，char ** argv）”的VideoCapture

Question

I'm trying to use VideoCapture. a part of my code is below.

when I run my code, I got this :

Error! Insufficient parameters provided.

How can I use my video with this code. I want to open a stream with VLC. Or if is there any other way, I'd like to use.

I searched that argv[1] is will be my video file. But I don't know how to show my file and how to define my file to this code.

Answer 1

To help future users, I'd make some changes:

Was:

LOG_DEBUG("Error! Insufficient parameters provided.");

Is:

std::string program(argv[0]);
LOG_DEBUG("Error! Insufficient parameters provided.");
LOG_DEBUG("Please provide a command line argument.");
LOG_DEBUG("Example:  " << program << " VIDEO_FILE_NAME");

Explanation:

On the command line, when the program is invoked, the arguments from the command line are copied in the array of strings held by argv . argv[0] is the first argument and it is the filename of the program itself. Put another way, argv[i] for 0 <= i < argc are populated in the array of strings argv from the command line. If you renamed the program executable file, argv[0] would be different the next time you ran the program.

The array argv is indexed from 0 to argc-1 . When main is invoked this array of strings and argc are set. It's up to the software to decide what to do. In this case your application tests argc and finds that if no argument is provided (ie., argc < 2) then the one user argument provided by the user is not present, report the error and return.

Incidentally, there's yet another form of main you can use:

int main(int argc, char** argv, char** envp)

argc = number of arguments. argv = array of argument strings envp = array of environment variable name=value pairs

So beyond simple command line argument passing, one could choose to write the main function to grab the environment variables (not shell variables) and decide nuanced action based on that. Options abound.

But for the time being, your code would be helpful if it reported why there is an error and the suggestions provided seem to do that.

Good luck.