On Thu, Jun 02, 2016 at 07:22:38AM +0200, fuumind wrote:
> I wish to convert several thousands of audio files mostly in mp3 format
> to AAC

I don't get why one would want to convert _to_ AAC. It's a format both bad
and proprietary, thus hardly supported by free software at all. It wins
with mp3 only at very low bitrates and is actually _worse_ (although usually
within the error margin) than mp3 on high bitrates.

If your target machine is anything non-ancient, you want opus, it thoroughly
beats both mp3 and aac at any bitrate. Even I, with untrained ears and
shitty gear, can ABX 320kbit mp3 on some samples. Never tried with aac but
it's said to be similar. On the other hand, pretty few people can ABX opus
at just 96k, so encoding at 128k is fine if you're paranoid about quality.
Yes, it is that much better.

If your target _is_ ancient, you want mp3 for compatibility. You'd need to
encode at a crap quality to let aac be significantly better.

> but AAC does not present itself as an available target

It's patented out of the wazoo.

--
An imaginary friend squared is a real enemy.