Well if you have this error when you try to install ffmpeg then you must download lame from sourceforge
wget http://downloads.sourceforge.net/project/lame/lame/3.98.4/lame-3.98.4.tar.gz?r=http%3A%2F%2Fffmpeg.zeranoe.com%2Fforum%2Fviewtopic.php%3Ff%3D5%26t%3D94&ts=1339140293&use_mirror=ignum
After
tar -zxvf lame-3.98.4.tar.gz
cd lame-3.98.4
./configure
make
make install
Don’t forget about ldconfig
