This is done with the 11.09 BSP for imx53 specifically.
Attached is an amrnb.spec file, I put it in ltib/dist/lfs-5.1/amrnb.
Then I extracted opencore-amr-0.1.3.tar.gz and put it in ltib/rpm/BUILD.
I built with ltib ( ALl this could be added to the ltib menus as well ):
./ltib –m scbuild –p amrnb
./ltib –m scdeploy –p amrnb
Then I applied the patch to .ltib for gst-plugins-ugly and built that with ltib.
It will play a .3gp file with this pipeline:
gst-launch filesrc location=/media/sd/test.3gp ! qtdemux name=demux demux.audio_00 ! queue ! amrnbdec ! alsasink demux.video_00 ! multiqueue ! mfw_vpudecoder ! mfw_isink