官方教程中的GStreamer示例不能使用GStreamer 1.14.1在Ubuntu 18.04上运行

Question

我安装了一个新版本的Ubuntu 18.04，我试图通过运行Gstreamer文档（https://gstreamer.freedesktop.org/documentation/tutorials/basic/gstreamer-tools.html）中的确切命令来解压缩Matroska文件中的单个通道。

Gstreamer是最新的：

gst-launch-1.0 --version
gst-launch-1.0 version 1.14.1
GStreamer 1.14.1
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

问题是Gstreamer一直在抱怨：

GstMatroskaDemux:d: Delayed linking failed

错误：

gst-launch-1.0 souphttpsrc location=https://www.freedesktop.org/software/gstreamer-sdk/data/media/sintel_trailer-480p.webm ! matroskademux name=d d.video_00 ! matroskamux ! filesink location=sintel_video.mkv
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
Got context from element 'souphttpsrc0': gst.soup.session=context, session=(SoupSession)NULL, force=(boolean)false;
WARNING: from element /GstPipeline:pipeline0/GstMatroskaDemux:d: Delayed linking failed.
Additional debug info:
./grammar.y(510): gst_parse_no_more_pads (): /GstPipeline:pipeline0/GstMatroskaDemux:d:
failed delayed linking pad  video_00 of GstMatroskaDemux named d to some pad of GstMatroskaMux named matroskamux0
ERROR: from element /GstPipeline:pipeline0/GstSoupHTTPSrc:souphttpsrc0: Internal data stream error.
Additional debug info:
gstbasesrc.c(3055): gst_base_src_loop (): /GstPipeline:pipeline0/GstSoupHTTPSrc:souphttpsrc0:
streaming stopped, reason not-linked (-1)
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
Freeing pipeline ...

我怎样才能让它发挥作用？谢谢。