Relief

1. apt-get source ffmpeg

2. apt-get build-dep ffmpeg

3. Download AMR and extract refer to the source libavcodec/amr.c, can either use amr_nb or amr_nb-fixed (not both at the same time).

4. Edit debian/rules and add 'confflags += --enable-amr_nb --enable-amr_wb'

5. fakeroot debian/rules binary

6. dpkg -i the built deb files