Est-ce qu'Audacity effectue les opérations d'édition de MP3

RE: Audacity 1.3.7 & MP3

1/ If I edit (namely cut, paste) an MP3 and export it again as an MP3, does Audacity make a re-encoding of the file, viz is it a lossless editing or does Audacity re-encode in MP3 the modified sound file?
I believe that Audacity imports the MP3 and converts it in some project base encoding format.
One edits and when one saves Audacity converts it to MP3, meaning a lossy operation.

2/ What happens in terms of encoding if one splits a stereo MP3, delete one channel say left, make it as mono and then save it? Indeed, I have MP3 speached as joint stereo, but which are actually mono, so to same space I wish to convert them to mono but in a “lossless” way.

Distrait tellement habitué à poser les questions en anglais que je l’ai mis en anglais
En bref en français

Est-ce qu’Audacity effectue les opérations d’édition de MP3 sans ré-encodage?

Pas d’après MP3DirectCut