2017-02-23 21:33:35 -0600 | answered a question | OpenCV: VideoCapture::get(CV_CAP_PROP_POS_MSEC ) returns 0 not really an answer.. more the way to eventually one.. i have tested the what happens with some debugging statements in the code: first i added some debug statements in cap_libv4l.cpp#L1414 and in cap_v4l.cpp#L1651 recompiled OpenCV and tested with an simple cam viewer. found that with the current setup it is using cap_v4l.cpp - and that only the first time my debugmessage was triggerd. so i added some some more debug output to cap_v4l.cpp L1651: with this i get the last line comes from my app.. so the capture->timestamp contains 0. it is set in cap_v4l.cpp#L868 directly from the buffer. so it seams OpenCV does not get a timestamp information from the ioctl call back :-( now at this point i have no idea how to go on... could be a problem in the v4l2 implementation?? |
2017-02-23 19:51:28 -0600 | commented question | OpenCV: VideoCapture::get(CV_CAP_PROP_POS_MSEC ) returns 0 i have the same problem. using OpenCV 3.2. self compiled from git. @berak: its not clear which one is used but the functionality is available in both: cap_v4l.cpp https://github.com/opencv/opencv/blob/master/modules/videoio/src/cap_v4l.cpp#L159 (L159) https://github.com/opencv/opencv/blob/master/modules/videoio/src/cap_v4l.cpp#L1651 (L1651) and cap_libv4l.cpp https://github.com/opencv/opencv/blob/master/modules/videoio/src/cap_libv4l.cpp#L194 (L194) https://github.com/opencv/opencv/blob/master/modules/videoio/src/cap_libv4l.cpp#L1414 (L1414). so this should not make a difference. it seems internally |