Gstreamer 1.2.3 missing

I’m trying to install gstreamer 1.2.3. But it always returns, that gstreamer 1.2.0 is installed. How can i update gstreamer to the new version?

To give some more information:

  • Raspberry Pi with Wheezy
  • apt-get update was done (install distribution upgrade as well)
  • python 2.7 is installed (does it require 3?)
  • the errors appears in case of starting mopidy

Which commands do I need to send in order to upgrade gstreamer to 1.2.3?

I’m confused, Wheezy doesn’t have gstreamer1.0. Although wheezy-backports does, there is no wheezy-backports for Raspbian.

EDIT:
OK, I remember now:

Upgrade to Jessie.