Convert audio to AAC and remux video

I remux all my mkv’s to mp4. I would like to convert audio to AAC (stereo) at the same time .

How can I do this ?

See the MP4 normal profile for how to convert audio to AAC

But I don’t wish to convert Video.

I use the unprocessed option an that doesn’t touch video or audio.

I want it to convert audio to AAC and keep video unchanged

would this work

[MP4 Unprocessed & AAC]
Description=Very fast but limited functionality. Use this profile if the original video has H.264/MPEG video and you want to remove the commercials and convert the file format to MP4 (e.g. WTV to MP4) without any additional processing (deinterlace, resizing, volume, cropping etc). It will copy the original video and audio and put it into a MP4 format unaltered in quality.
ffmpeg-general=-threads 0
ffmpeg-video=-ss 0 -vcodec copy -sn
ffmpeg-audio=-acodec copy
ffmpeg-audioac3=-acodec libfdk_aac -ab 160k -cutoff 18000 -map 0:a

Yes it should. If the audio track is ac3 it’ll convert it otherwise it’ll copy it.