GStreamer in ubuntu 18

[Andrés Meseguer Valenzuela]

Hi, I am trying to use GStreamer 1.18 in my ubuntu 18. Due to the fact  
that is not possible to get it, trying to install it using the  
commands specified in this webpage:  
https://gstreamer.freedesktop.org/documentation/installing/on-linux.html?gi-language=c

I am trying to install it with meson and ninja, with these steps:
meson builddir
ninja -C builddir install
reference: https://gitlab.freedesktop.org/gstreamer/gst-build

But when I try to use gst-inspect, it returns a 1.14 version.

Please, would you tell me how to use version 1.18?

My objective is to use GStreamer in Ubuntu 18, with .sh files.

Thanks for your time.
Regards,
Andres