root@OpenWrt:~/recordings# ffmpeg -f oss -i /dev/audio test4.mp3
ffmpeg version 0.8.7, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov 18 2012 02:58:08 with gcc 4.6.3 20120201 (prerelease)
  configuration: --enable-cross-compile --cross-prefix=mips-openwrt-linux-uclibc- --arch=mips --target-os=linux --prefix=/usr --enable-shared --enable-static --disable-debug --pkg-config=pkg-config --enable-gpl --enable-version3 --disable-asm --disable-doc --disable-dxva2 --enable-pthreads --disable-optimizations --enable-small --disable-stripping --enable-zlib --disable-outdevs
  libavutil    51.  9. 1 / 51.  9. 1
  libavcodec   53.  8. 0 / 53.  8. 0
  libavformat  53.  5. 0 / 53.  5. 0
  libavdevice  53.  1. 1 / 53.  1. 1
  libavfilter   2. 23. 0 /  2. 23. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[oss @ 0xa3e410] Estimating duration from bitrate, this may be inaccurate
Input #0, oss, from '/dev/audio':
  Duration: N/A, start: 1360636580.366095, bitrate: N/A
    Stream #0.0: Audio: pcm_s16be, 48000 Hz, 2 channels, s16, 1536 kb/s
Output #0, mp3, to 'test4.mp3':
    Stream #0.0: Audio: [0][0][0][0] / 0x0000, 48000 Hz, 2 channels, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
Encoder (codec id 86017) not found for output stream #0.0