c# - Get real timestamp of frame captured using OpenCV -

i'm using emgucv wrapper opencv capture live video ip camera.

i'm trying frame timestamp using function

capture _capture = new capture(url); _capture.imagegrabbed += capture_imagegrabbed;  private void _capture_imagegrabbed(object sender, eventargs e) {    mat frame;    _capture.retrieve(frame);    double ts = getcaptureproperty(capprop.posmsec); } 

the function work, return position of frame beggining of capturing , not device clock timestamp.

in manual of emgucv , opencv says:

getcaptureproperty(cv_cap_prop_pos_msec) returning film current position in milliseconds or video capture timestamp

is there way choose if return film position or timestamp?

thanks