Something

ffmpeg -v
FFmpeg version SVN-r9707, Copyright (c) 2000-2007 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-pp --enable-libvorbis --enable-libogg --enable-dc1394 --disable-debug --enable-libmp3lame --enable-libfaad --enable-libfaac --enable-pthreads --enable-libx264 --disable-ffserver --disable-ffplay --disable-network --disable-ipv6

ffmpeg -y -i nipplefire.avi -f mp4 -pass 2 -subq 5 -threads auto -v 1 -vcodec h264 -b 800k -bt 768k -refs 5 -loop 1 -parti4x4 1 -partp8x8 1 -partb8x8 1 -me umh -me_range 16 -chroma 1 -bf 0 -level 30 -g 300 -keyint_min 30 -sc_threshold 40 -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.7 -qmax 51 -qdiff 4 -i_qfactor 0.71428572 -maxrate 1600k -bufsize 244k -cmp 1 -s 640x480 -acodec aac -ab 64k -ar 48000 -ac 2 temp.mp4

Unknown codec 'aac'

ffmpeg -formats 2>/dev/null |grep aac
 D  aac             ADTS AAC
  EA    libfaac
 D A    mpeg4aac