====== wav ======

===== wav to mp3 ======
ffmpeg -i audio.wav -acodec libmp3lame audio.mp3

===== wav to ogg ======

ffmpeg -i audio.wav  -acodec libvorbis audio.ogg

===== wav to aac ======
ffmpeg -i audio.wav  -acodec libfaac audio.aac

===== wav to ac3 ======
ffmpeg -i audio.wav -acodec ac3 audio.mp3



====== ogg ======
===== ogg to mp3 =====
ffmpeg -i audio.ogg -acodec libmp3lame audio.mp3

===== ogg to wav =====
ffmpeg -i audio.ogg audio.wav

===== ogg to aac =====
ffmpeg -i audio.ogg  -acodec libfaac audio.aac

===== ogg to ac3 =====
ffmpeg -i audio.ogg -acodec ac3 audio.ac3



====== ac3 ======
===== ac3 to mp3 =====
ffmpeg -i audio.ac3 -acodec libmp3lame audio.mp3

===== ac3 to wav =====
ffmpeg -i audio.ac3 audio.wav

===== ac3 to aac =====
ffmpeg -i audio.ac3  -acodec libfaac audio.aac

===== ac3 to ogg =====
ffmpeg -i audio.ac3 -acodec libvorbis audio.ogg



====== aac ======
===== aac to mp3 =====
ffmpeg -i audio.aac -acodec libmp3lame audio.mp3

===== aac to wav =====
ffmpeg -i audio.aac audio.wav

===== aac to ac3 =====
ffmpeg -i audio.aac  -acodec ac3 audio.ac3

===== aac to ogg =====
ffmpeg -i audio.aac -libvorbis audio.ogg

===== aac to ac3 =====
ffmpeg -i audio.aac  -acodec ac3 audio.ac3


====== mp3 ======
===== mp3 to aac(mp4) =====
ffmpeg -i audio.mp3 -acodec libvo_aacenc output.mp4