Comment 5 for bug 340408

I have a way to have the 3gp audio decoder, which is called AMR codec.

follow these steps:
1) open the update manager settings
2) enable the source repositories
3) add the medibuntu repository:
deb http://packages.medibuntu.org/ jaunty free non-free #medibuntu
4) close the manager and reload the package list
5) install those packages, which will let you build .deb:
sudo apt-get install fakeroot dpkg-dev devscripts debhelper
build-essential bsd-mailx- postfix-
6) install the AMR codec and its developement packages:
sudo apt-get install libamrnb-dev libamrwb-dev
7) install the packages required to build ffmpeg:
sudo apt-get build-dep libavformat-unstripped-52
8) download the ffmpeg source and cd into the directory:
apt-get source libavformat-unstripped-52
cd ffmpeg*
9) enable the AMR codec in the configure script
echo "confflags += --enable-nonfree --enable-libamr-nb
--enable-libamr-wb" >> debian/confflags
10) increment the package version, so it does not get replaced during upgrades
dch -i "Added AMR support"
11) build the package:
DEB_BUILD_OPTIONS="--enable-externalcodecs" debuild -rfakeroot -uc -us -b
12) install the generated packages:
cd ..
sudo dpkg -i libavcodec*52_*.deb libavdevice*52_*.deb
libavfilter*0_*.deb libavformat*52_*.deb libavutil*49_*.deb
libpostproc*51_*.deb libswscale*0_*.deb
13) save the packages and delete everything else, because it will save
some space

let me know please if something does not work!