How to transcode aac file to mp3 file using encoder?

[stax76]

All tutorials I've found deal with video files making me wonder if mencoder can work with audio files only. How would I transcode a aac file to a mp3 file?

[nm]

Try this hack: TOOLS/aconvert.sh (http://svn.mplayerhq.hu/mplayer/trunk/TOOLS/aconvert.sh?content-type=text%2Fplain&view=co)

[stax76]

I was hoping for a simple windows solution, maybe ffmpeg does a better job.

[nm]

This might not be the best place to ask for Windows solutions :)

Anyway, the script is quite simple and I'm pretty sure that it could be modified to work on the Windows command line too. Here's the main command for MP3 encoding:mencoder -demuxer rawvideo -rawvideo w=1:h=1 -ovc copy -oac mp3lame -of rawaudio -audiofile INPUT -o OUTPUT INPUT
Note that the input file is given two times, both as audio (-audiofile INPUT) and as raw video (-demuxer rawvideo -rawvideo w=1:h=1 INPUT). MEncoder will ignore the video stream because of the specified 1x1 resolution (it is a hack). Only a raw audio stream is written to the output file (-of rawaudio).

The only practical problem with this command is that the encoding will go on for a long time unless you tell MEncoder to stop it at the end of the audio input by specifying "-endpos INPUT_DURATION_IN_SECONDS". This duration can be found out with "mplayer -identify", as is done in aconvert.sh:mplayer -identify INPUT -frames 0 2>&1 | grep ID_LENGTH | cut -d "=" -f 2You can either come up with a Windows script/program to do this or specify the duration manually. Or simply use something like -endpos X, where X is larger than any expected input duration (for example, 36000 seconds = 10 hours).

But yes, ffmpeg handles audio-only encoding better.

[Selur]

Note that the input file is given two times, both as audio (-audiofile INPUT) and as raw video (-demuxer rawvideo -rawvideo w=1:h=1 INPUT). MEncoder will ignore the video stream because of the specified 1x1 resolution (it is a hack). Only a raw audio stream is written to the output file (-of rawaudio).
cool didn't know this 'hack' thanks for the info :)
really prefer mencoder audio handling since it can do an way better downsampling than ffmpeg. ;)

[buzzqw]

great hint! thanks nm!

BHH