This is the most reliable method for trouble-free editing. Convert your external audio to AAC in an M4A container or MP3 in an MP3 container.
Using Audacity (Free):
Using FFmpeg (Command Line):
ffmpeg -i input.mp3 -c:a aac -b:a 192k -ar 48000 output.m4a
Error Message: Avidemux cannot use that file as audio track
Software: Avidemux (commonly v2.7+ on Windows/Linux/macOS)
Context: User attempts to load an external audio file (MP3, AAC, WAV, etc.) as a replacement or additional audio track for a video.
Symptoms: Error appears immediately after selecting the audio file, preventing further processing. avidemux cannot use that file as audio track
If your external audio is already in a compatible format but Avidemux still complains, try creating a "dummy" audio track first. This is the most reliable method for trouble-free editing