Opencv error on video: gstreamer missing required plugin

$ python
Python 3.6.8 (default, Jan 31 2019, 09:06:51)
[GCC 8.2.1 20181215 (Red Hat 8.2.1-6)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cap = cv2.VideoCapture('chaplin.mp4')
Failed to query video capabilities: Inappropriate ioctl for device
libv4l2: error getting capabilities: Inappropriate ioctl for device
VIDEOIO ERROR: V4L: device ../GOTURN/chaplin.mp4: Unable to query number of channels
OpenCV(3.4.1) Error: Unspecified error (GStreamer: your gstreamer installation is missing a required plugin
) in handlemessage, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp, line 1869
VIDEOIO(cvCreateCapture_GStreamer (CV_CAP_GSTREAMER_FILE, filename)): raised OpenCV exception:

OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp:1869: error: (-2) GStreamer: your gstreamer installation is missing a required plugin
in function handlemessage

>>>

I have tried multiple video files (mp4). All have the same problem. If you couldn't reproduce the problem, I can upload my video file (although I don't think it's necessary).

谢谢，方便提供一下rpm吗？

The problem is fixed. Thanks!

sudo dnf install gstreamer-rockchip

可以打开视频。不过有warning说读不到视频的channel和duration，请定位一下是什么问题。信息如下：

Failed to query video capabilities: Inappropriate ioctl for device
libv4l2: error getting capabilities: Inappropriate ioctl for device
VIDEOIO ERROR: V4L: device /home/toybrick/video.mp4: Unable to query number of channels
mpi: mpp version: Without VCS info
mpp_rt: NOT found ion allocator
mpp_rt: found drm allocator
mpp: deprecated block control, use timeout control instead
warning: GStreamer: unable to query duration of stream (/builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp:904)
warning: Cannot query video position: status=1 value=0 duration=-1
(/builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp:952)