"Cannot use that file as audio track" in Avidemux typically occurs because the software is designed to accept only raw audio streams
Even if the file format is supported, Avidemux might not support the specific codec used within that file. avidemux cannot use that file as audio track
Use ffmpeg (command line) or Audacity to convert: "Cannot use that file as audio track" in
AAC: Must be in an ADTS envelope (raw .aac file), not a .m4a container. AC3/E-AC3: Standard Dolby Digital formats. 2. Re-wrap with FFmpeg (Advanced) Check file details: open the audio file in
Recommendation: If you need to add an MP3 to an MP4 without re-encoding, use MKVToolNix to create an MKV file (which happily accepts MP3). Then use Avidemux to edit that MKV.
Avidemux is designed to be a "linear" editor, meaning it prefers to process video and audio streams directly without re-encoding them whenever possible. Because of this, it is notoriously picky about the format of external audio files you try to import.