How to reencode a 6 channels AAC file to a proper AC3 file
First why doing that :
- My home cinema only handle AC3 and DTS.
- There's no easy way (I know you can special alsa output to do that) to make mplayer reencode the AAC into AC3 during playback
- AC3 is a much more universal format (at least for now)
You'll need :
- faad (a simple aptitude install faad will do)
- aften (see here), you'll need to build it from the sources.
Then the easiest way to avoid having a really big intermediate file is to use a fifo :
mkfifo temp.wav screen -d -m faad -o temp.wav input.aac aften temp.wav output.ac3 rm temp.wav
I use screen to launch faad because to make sure faad and aften are running at the same time (whole purpose of using a fifo), you can also use two terminals.
Note that faad seems to have a problem displaying the correct pourcentage decoded so don't trust it.