Avidemux differs from Non-Linear Editors (NLEs) like Premiere Pro or DaVinci Resolve. In those programs, the software automatically converts audio to match the project settings. Avidemux, however, is designed to be a "direct stream copy" editor. It prefers not to re-encode data unless absolutely necessary.
When you see the "Cannot use that file as audio track" error, it usually means Avidemux does not have a decoder installed or activated that can read the specific format of your audio file.
The most common culprit? AAC audio wrapped in an M4A container. avidemux+cannot+use+that+file+as+audio+track
Avidemux has a complex history with AAC audio due to licensing issues. While it can often play AAC audio inside a video file, it may struggle to import a standalone AAC/M4A file as an external track if the specific internal decoder isn't loaded.
Before fixing the error, you must understand how Avidemux thinks. Unlike modern editors that use a timeline and re-encode everything seamlessly, Avidemux is a smart copy tool. It works best when it doesn't have to convert data. The error "cannot use that file as an
When you add an external audio track, Avidemux does not want to transcode it on the fly. It wants to copy the audio stream directly into the output container (MKV, MP4, AVI). For this to work, three conditions must be met:
The error "cannot use that file as an audio track" almost always stems from a violation of one of these three rules. If your external audio file is shorter or
If your external audio file is shorter or longer than the video by a fraction of a second, Avidemux’s copy mode may panic.
The Fix:
In Audio > Main Track, check Shift and Delay. Don't change them; just toggle the checkbox. Sometimes this forces Avidemux to recalculate the duration. Alternatively, use Audacity to trim/silence the audio to exactly match the video length (down to the millisecond).