The audio file is in a container or codec that Avidemux cannot parse (e.g., specialized FLAC, Vorbis, or proprietary formats).
In the section, uncheck the original audio track of the video, and make sure your new external audio track is checked. Click Start multiplexing at the bottom.
Launch Avidemux and drag-and-drop your main video file into the workspace.
Avidemux is a popular, free video editor used for quick cutting, filtering, and encoding. However, many users encounter a frustrating roadblock when trying to add an external audio track to their video: avidemux+cannot+use+that+file+as+audio+track
This issue pops up when you try to import an external audio file (like an MP3, WAV, or AAC track) using the "Select Audio Track" menu. Avidemux abruptly rejects the file, halting your editing workflow.
Open the newly created .mkv file directly in Avidemux. Your audio will already be perfectly embedded. Solution 3: Use Command Line (FFmpeg Quick Fix)
ffmpeg -i temp_video.mkv -i fixed_audio.wav -c:v copy -map 0:v:0 -map 1:a:0 -c:a aac -shortest final_video.mp4 The audio file is in a container or
In this guide, we will explore why this happens and provide comprehensive, actionable solutions to resolve the issue in 2026. Why Does This Error Occur?
The process is the same:
Avidemux sometimes refuses standalone audio files but will gladly accept them if they are wrapped inside a video container. You can use a lightweight tool like to trick Avidemux: Download and open MKVToolNix GUI . Drag your source video file into the Source files box. Drag your external audio file into the same box. Launch Avidemux and drag-and-drop your main video file
Here is the complete, correct workflow:
On the left-hand panel, set Video Output to Copy (if you don't want to re-encode the video) and Audio Output to AAC (Faac) , MP3 , or Copy (depending on your preference). Save: Click File > Save to render the combined file. Alternative Solutions: When Avidemux Still Fails
Always make sure the audio file duration matches your video duration before importing, or you’ll end up with a "drifting" sync error that’s much harder to fix later.
In the case of AAC, it's even more specific: Avidemux needs it encapsulated in an (Audio Data Transport Stream) or LATM (Low-Overhead Audio Transport Multiplex) stream. This is essentially a thin wrapper that presents the AAC data in a stream-ready format.