Ubuntu 12.04 install ffmpeg with amr support

1)Install the source package
apt-get source ffmpeg


2) install dependencies to build the package
apt-get build-dep ffmpeg


3) Install dependencies for custom options (confflags)
apt-get install libopencore-amrnb-dev libopencore-amrwb-dev

4) ffmpeg is on of the components of libav so apt-get source ffmpeg will create /usr/src/libav-0.8.3 with the source so cd to that location
cd /usr/src/libav-0.8.3

4) change confflags to enable some extra options for ffmpeg
vim debian/confflags
add following lines in '# Common configuration flags' section
confflags += --enable-libopencore-amrwb
confflags += --enable-libopencore-amrnb
confflags += --enable-version3

5) Build the package
dpkg-buildpackage -rfakeroot -uc -b

6) Install the resulting deb package(s)

cd /usr/src

dpkg -i ffmpeg_0.8.3-0ubuntu0.12.04.1_all.deb

7) Using ffmpeg to convert mp3 to amr
ffmpeg -y -vn -i in_file.mp3 -y -acodec libvo_amrwbenc -ac 1 -ar 16000 -ab 7.4k -f amr -map_metadata  -o out_file.amr

Generate wallpaper slideshow xml for gnome/Unity

#!/bin/bash

start='<background><starttime><year>2009</year><month>08</month><day>04</day><hour>00</hour><minute>00</minute><second>00</second></starttime>';
end='</background>';
static='<static><duration>1000.0</duration><file>%s</file></static>';
transition='<transition><duration>5.0</duration><from>%s</from><to>%s</to></transition>';

echo $start
echo
prev_file='';
ls | grep -i -e .jpg -e .png | while read line
do
   file=$PWD/$line;
   if [[ $prev_file == '' ]]
   then
      printf $static "$file";
      echo
   else
      printf $transition "$prev_file" "$file";
      echo
      printf $static "$file";
      echo
   fi
   prev_file=$file;
done
echo $end

1) In ubuntu precise the xml which provides the wallpaper slideshow is located here
/usr/share/backgrounds/contest/precise.xml

2) In order to create your own xml file you have to cd to the directory which contains the images and run this script and recirect the output to an xml file

3) After createing the xml file (eg: myshow.xml) backup the original file comes with precise and replace the newly created file to its place with the same name (precise.xml)

4) Go to system settings > appearance and select your slide show there

NOTE: make sure to keep your image filenames without spaces or use following script to replace spaces with underscores

#!/bin/bash

ls | grep '[a-zA-Z0-9]\ [a-zA-Z0-9]' | while read line
do
mv "$line" $( echo $line | sed s/' '/'_'/g )
done