GStreamer：没有元素

Question

我正在尝试从 Raspberry Pi 4 运行 UDP 流，并使用它安装了 gstreamer，可以在 gstreamer 的文档中找到：

$ sudo apt-get install libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev \
libgstreamer-plugins-bad1.0-dev gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly gstreamer1.0-libav gstreamer1.0-doc gstreamer1.0-tools \
gstreamer1.0-x gstreamer1.0-alsa gstreamer1.0-gl gstreamer1.0-gtk3 gstreamer1.0-qt5 gstreamer1.0-pulseaudio

此外，我还安装了x264和v4l-utils。但是，当尝试执行诸如

$ gst-launch-1.0 videotestsrc
$ gst-launch-1.0 v4l2src

它因错误而失败

ERROR: pipeline could not be constructed: no element "videotestsrc"
ERROR: pipeline could not be constructed: no element "v4l2src"

之前帖子的一些答案是运行，无论输入什么，gst-inspect-1.0 videotestsrc它总是给我。symbol lookup error: gst-inspect-1.0: undefined symbol: GST_CAT_DEFAULT

我也尝试过跑步export LD_LIBRARY_PATH=/lib:/usr/lib:/usr/local/lib，sudo ldconfig但没有成功。

到目前为止，完全重新安装 Gstreamer 尚未成功。有任何想法吗？