copy flv to mp4 or mp3 formatted videos with ffmpeg

copy stanza -vcodec copy -acodec copy

ffmpeg -i input.flv -vcodec copy -acodec copy output.mp4

with audio re-encode

ffmpeg -i input.flv -vcodec copy -acodec mp2 -ar 44100 -ab 128k output.mp4

upgrade audio encode

ffmpeg -i input.flv -vcodec copy -acodec libfaac -aq 200 output.mp4

mp3 encode (requires codecs to be added)
ffmpeg -i input.flv -acodec libmp3lame -aq 4  output.mp3

additional codecs for 11.10
sudo apt-get -y install ffmpeg libavcodec-extra-52
or
sudo apt-get -y install ffmpeg libavcodec-extra-53

link to codec discussion:
http://ubuntuforums.org/showthread.php?t=1117283


link to encoding discussion:
http://ubuntuforums.org/showthread.php?t=1493682