Using device name instead of ID in OpenCV method VideoCapture.open()

Question

I have a lot of video devices in my /dev folder (e.g. video1, video2, ..., video9) and one /dev/video which

Answer 1

The best thing is to parse the ID of the device.

#include 
#include 

...

boost::filesystem::path path( "/dev/video3" );
auto target = boost::filesystem::canonical(path).string();
std::regex exp( ".*video(\\d+)" );
std::smatch match;
std::regex_search( target, match, exp );
auto id = strtod( match[1] );
auto cap = cv::VideoCapture( id );

Note the use of canonical() to make the path absolute and resolve any symbolic links. This way it works even if you give it v4l device paths from /dev/v4l/by-id or /dev/v4l/by-path like for example:

"/dev/v4l/by-id/usb-046d_0990_1188AD49-video-index0"
"/dev/v4l/by-path/pci-0000:00:13.2-usb-0:4.4.4:1.0-video-index0"