[linux-audio-user] Converting from / to MPEG-4 audio files

Tim Orford tim at orford.org
Sat Jul 17 03:32:18 EDT 2004

> I've got a bunch of files in MPEG-4 format (x.m4a) - is there any 
> software to convert them to either mp3 or (preferably) ogg or flac 
> files?

assuming that the file is aac encoded:

libfaaad (http://www.audiocoding.com/) provides aac decoding on linux:

"FAAD2 is the fastest ISO AAC audio decoder available. FAAD2 correctly
decodes all MPEG-4 and MPEG-2 MAIN, LC (Low Complexity), HE (High
Efficiency), LTP (Long Term Prediction), LD (Low Delay) and ER (Error
Resiliency) object type AAC files."

mplayer includes it internally, so (having paid the requisite fee to
the MPEG Licensing Authority) you *should* be able to decode to wav
like this:

mplayer -ao pcm -aofile <o/p audiofile> x.m4a;

if you wanted to get advanced you could pipe directly into flac or
vorbis encoders.

mplayer rocks!:-)

Tim Orford

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