0 - copy of the input audio stream
(-oac copy)
1 - pcm audio stream (-oac pcm)
2 - mp3lame fast (-oac mp3lame -lameopts fast)
3 - mp3lame standard (-oac mp3lame -lameopts preset=standard)
4 - mp2/libavcodec (-oac lavc -lavcopts acodec=mp2:abitrate=224)
5 - mp3/libavcodec,cbr (-oac lavc -lavcopts acodec=mp3:abitrate=128)
6 - ac3/libavcodec (-oac lavc -lavcopts acodec=ac3:abitrate=192)
7 - mp2/toolame (-oac toolame -toolameopts br=224)
8 - aac/libfaac (-oac faac -faacopts br=96)
Note: the audio bit rate can be specified in two ways: with the options
-abr or with a comma and the bitrate as part of the -encode argument.
-encode 5:1:1,128
or
-encode 5:1:1 -abr 128
are equivalent in Avi Mode