Error during adding new audio track

[igogo]

2.8.0 version + win10
I'm trying to combine together video and audio file. After opening video file i'm selecting Audio/Select track/...Add audio track and select file https://workupload.com/file/dRcNcG2L9FZ
As result i'm getting an error. You cannot view this attachment.

[eumagga0x2a]

Avidemux supports only raw AAC (more precisely, ADTS encapsulated as AAC is useless without its extradata), AC3, E-AC3, MP2 and MP3 streams as external audio tracks, so no MP4 like your sample or Matroska containers can be used for this purpose.

[igogo]

Is it possible to add the ability into application importing audio tracks in MP4 format?
If not could you advice me how to convert my MP4 audio track into any supported format?

[eumagga0x2a]

Is it possible to add the ability into application importing audio tracks in MP4 format?

No (nothing short of a major rewrite / redesign).

could you advice me how to convert my MP4 audio track into any supported format?

Code Select Expand

ffmpeg -i audio.mp4 -c copy audio.aac
does the trick.