Conversion of .aac files to flac or mp3 or what?

I have some downloaded files of radio programme from BBC which are .aac. I have never come across this type before. Googled it so now I am a bit wiser and VLC seems to play them without problem but they are not accepted by my upnp client devices which are happier with flac or mp3. I would prefer flac but what is the preferred conversion software. I should say I am wrestling with 11.4 and KDE.
Grateful for any experience informed advice please.
Budgie2

Hi,

The best app to convert is ffmpeg in terminal.

I another thread I suggested Soundkonverter from the KDE Extra repo. I suppose it might work here too.

Also make sure that your system is fit for all kinds of multimedia formats. This how-to is probably more that just a start:
Multi-media and Restricted Format Installation Guide

you can use konvertible