The best replacement for gstreamer is xine.

The best alternatives to gstreamer are rated as following:
★★★★★  xine
★★★★  ffmpeg
★★  mplayer
★★  gstreamer1
★★  directshow
★★  vlc phonon
★★  pulseaudio
★★  openmax
★  libvlc
★  opencore
★  live555
★  mlt
  phonon
  alsa
  mediastreamer2
  phonon vlc
  totem xine

Your alternative for gstreamer is not listed? Suggest!
Speaking about gstreamer, one probably shouldn't forget about qt.

Other search terms related to gstreamer and their ratings are:
★★★★★ qt
★ amarok
You have in mind a companion for gstreamer and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of gstreamer in all years. Click on graph for more.
gstreamer
xine
ffmpeg