M4A to wav

 for nam in *.M4A; do nice mplayer -ao pcm "$nam" -ao pcm:file="$nam.wav" done

wav to mp3

 for nam in *.wav; do nice lame -h "$nam" "$nam.mp3" ;done


reference
http://gimpel.gi.funpic.de/wiki/index.php?title=Howto:convert_aac/mp4_to_wav/mp3/ogg_on_Linux
posted by citadel
 lame -h input.wav output.mp3

       -h     Use  some quality improvements.  Encoding will be slower, but the result will be
              of
higher quality.  The behaviour is the same as the -q 2 switch.
              This switch is always enabled when using VBR.




ffmpeg -i input.wav -ab 64 -ac 1 -ar 44100 output.mp3
Note that the output detailed format is MPEG Layer II.

ffmpeg -i input.wav -ab 64 -ac 1 -ar 44100 output.flac

 Audio Options

       -ar freq
           Set the audio sampling frequency (default = 44100 Hz).
       -ab bitrate
           Set the audio bitrate in kbit/s (default = 64).
       -ac channels
           Set the number of audio channels (default = 1).
       -an Disable audio recording.

       -acodec codec
           Force audio codec to codec. Use the "copy" special value to specify that the raw codec
           data must be copied as is.

2007/10/12 - [computer/linux] - How to convert wmv to flv with ffmpeg and embed in my web site.


posted by citadel