Opencv error on video: gstreamer missing required plugin

VIDEOIO ERROR: V4L: device rtsp://admin:admin12345@192.168.0.191:554/h264: Unable to query number of channels
OpenCV(3.4.1) Error: Unspecified error (GStreamer: unable to start pipeline
) in cvCaptureFromCAM_GStreamer, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp, line 890
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:890: error: (-2) GStreamer: unable to start pipeline
in function cvCaptureFromCAM_GStreamer

Open camera error!

如果是C++出现音频音频编解码的错误应该怎么办啊？？都卡了一个星期了