multithreading - OpenCV VideoCapture does not block on OS X -

short version: on os x, if call videocapture::read() thread other main() thread, call returns instead of blocking till new frame.

this 1 works expect:

void main() {     videocapture vc(0);      mat img;     while(1) {         vc.read( img ); // blocks till new frame arrives     }     } 

this 1 not block:

void run( videocapture& vc ) {     mat img;     while(1) {         vc.read( img ); // returns , returns true     }     }  void main() {     videocapture vc(0);     boost::thread capthread( boost::bind( &run, vc ) );     capthread.join(); } 

so in second version separate thread grab frames, call videocapture::read(img) returns return value true, , img set current frame, means it'll return many duplicate frames.

it's mentioned here:

problem accessing camera when using boost thread on osx

that:

"the opencv camera functions on mac require access objective-c nsrunloop; don't know how @ 1 new thread though."

anyone know of solution blocking frame grab thread other main() thread? alternatively, there nice way discard duplicate frames?

thanks

opencv doesn't support multi-threading.

let main thread capture frames , whatever need in second thread.