Hi - I've been recording one of my classes with my android phone, and the file it gives me is an .amr file. I'd like to convert that to .mp3, and I was hoping I could use ffmpeg to do it via the command line. Here's what I did, and the output that I got:

roger@KarmaLaptop:~/Desktop$ ffmpeg -i Net202-week6.amr Net202-week6.mp3
FFmpeg version 0.6-4:0.6-2ubuntu6, Copyright (c) 2000-2010 the FFmpeg developers
built on Oct 5 2010 22:36:53 with gcc 4.4.5
configuration: --extra-version=4:0.6-2ubuntu6 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
libavutil 50.15. 1 / 50.15. 1
libavcodec 52.72. 2 / 52.72. 2
libavformat 52.64. 2 / 52.64. 2
libavdevice 52. 2. 0 / 52. 2. 0
libavfilter 1.19. 0 / 1.19. 0
libswscale 0.11. 0 / 0.11. 0
libpostproc 51. 2. 0 / 51. 2. 0
[amr @ 0x1fa7420]max_analyze_duration reached
[amr @ 0x1fa7420]Estimating duration from bitrate, this may be inaccurate
Input #0, amr, from 'Net202-week6.amr':
Duration: N/A, bitrate: N/A
Stream #0.0: Audio: amrnb, 8000 Hz, 1 channels, flt
Output #0, mp3, to 'Net202-week6.mp3':
Stream #0.0: Audio: 0x0000, 8000 Hz, 1 channels, flt, 64 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Encoder (codec id 86017) not found for output stream #0.0
roger@KarmaLaptop:~/Desktop$
It gives me an .mp3 file, but it's 0 bits, and obviously isn't containing any information. The last line of the output looked like I may be missing something, so I installed lame, but that didn't seem to make any difference. Can anybody point me in the right direction?