On Windows, download the from avidemux.org/nightly/ – these include more codecs.
Before diving into fixes, you need to understand one core concept:
Use -b:a (constant bitrate). Avidemux now sees predictable frames.
If using a WAV file and Avidemux rejects it, the header might be wrong. avidemux cannot use that file as audio track
Unlike Adobe Premiere or DaVinci Resolve, Avidemux does not automatically decode and re-encode every audio stream you throw at it. Instead, it tries to work directly with the existing audio frames. This is what makes Avidemux incredibly fast (no rendering for simple cuts), but also picky.
Another frequent culprit is the software’s "indexing" or "muxing" state. Avidemux operates by mapping out the video and audio frames. If the video file currently open has a different frame rate or duration than the audio track you are trying to add, the software may throw an error to prevent an out-of-sync export. Additionally, if the audio file is currently open in another program—such as a media player or another editor—Avidemux may be denied the "read" permissions necessary to load the track, resulting in a generic failure message.
You’ve tried everything. Avidemux still refuses your audio file. Here are last resorts: On Windows, download the from avidemux
When you try to add an external audio track, Avidemux attempts to "remux" or copy the stream directly into the output container. This brings us to the three main reasons why the "Cannot use that file as audio track" error pops up.
If you are reading this article, you have likely just encountered one of the most frustrating error messages in open-source video editing: You have a video file, you have a separate audio file (perhaps a commentary track, a background music MP3, or a corrected dialogue track), and you simply want to combine them in Avidemux. But despite your best efforts, the software refuses to cooperate.
sudo apt install avidemux-qt
Use HandBrake to transcode your video to a clean MP4 with AAC audio. Then load that fresh file into Avidemux.
What is the of the audio (e.g., .mp3, .m4a, .wav)?
Then load extracted_audio.aac as the audio track. If using a WAV file and Avidemux rejects